TBE
Newbie
Recently I was asked to do a reliability comparison test of the Sharps Rifle Company Relia-bolt and Balanced Bolt Carrier, and would like to share the results. In keeping with the P & S standards for high-confidence, detailed documentation to support opinions, this is a long post, be forewarned. Also, apologies in advance for the formatting. FB does not respect document formatting and much is cut-and-paste from other much longer documents or from spreadsheets.
The Test Subject:
The Sharps Rifle Company Relia-bolt design claims greater reliability due to the changing of the bolt lug profile to create more area/volume in the lug recess in the barrel extension for foreign material to accumulate without interfering with bolt function; additionally that the modified profile of the lugs are more conducive to moving foreign material aside and maintaining carrier speed and lock-up. Additional features or improvements on the bolt and carrier include NP3 Plus Nickel-Teflon bonded coating for additional dry lubricity; and an enhanced mass-distribution of the bolt carrier aka "Balanced Bolt Carrier" meant to improve cycling.
Before getting started, a full disclosure: I am a full-time industry guy providing training, R&D and design services. As such, I was paid for my time and was provided the ammunition to perform the test under the explicit understanding that the results would be impartial. To do otherwise would compromise both ethics and the data - which aside from potential marketing value, was also intended for future product improvement.
I have no financial interest in the company nor do I receive any compensation or commissions on this product. This was a one-off contract test, and I was paid to generate data, good or bad.. I have told a lot of people that their babies are ugly and am quite comfortable doing so. The following is for informational purposes, and I have received permission from the Sharps Rifle Company to share it. Don't contact me wanting to buy anything, that's not what I do.
Some background... After being contacted by a third party with a request to do the test, I did some internet research. I was immediately intrigued by the SRC design, however I also found some videos of people who had reportedly broken SRC bolts with some commentary that the S-7 steel used was too hard. I asked SRC about this and was informed that S-7 steel is very high tensile, wear resistant and is used in bolts and other parts by reputable manufacturers including Barrett Mfg. They attributed the reported breakage to a particular lot of bolts which had been improperly heat-treated and were run with high-pressure loads in a suppressed carbine (worst case). A recall was issued for the bolts identified. They have since changed the manufacturing process to prevent the issue from recurring and assured me no further problems have been encountered.
Being the natural-born skeptic, I asked for several bolts (8) so that I could have a larger sample group to observe for failure. While lug failures are nothing new (I have seen many failures in Carpenter 158 bolts as well) I still wanted to see if this might be an issue. Up front: There have been no failures of this type to date, with approximately another 15k rounds fired on 4 bolts which I have continued to use in student rifles subsequent to the test I will relate. The reliability test undertaken however, was not designed specifically to attempt to cause material failure by running high-pressure loads through suppressed carbines (the conditions of the previous 2 failures). So, with that caveat, I'll move ahead...
Purpose: The test was undertaken as a statistical direct comparison between the performance of traditional-design MILSPEC bolts / BCG's and the SRC bolt when exposed to variables known or suspected to cause malfunction. These included:
* Dry bolt without lubrication
* Over-lubricated bolt (dripping inside and out with CLP with subsequent migration into the chamber)
*Mud
*Coarse Sand
*Fine Dust
The testing had 2 key goals:
• Providing validation and proof of principle testing on the SRC bolt technology by comparison with traditional / MILSPEC design using test media simulating austere conditions.
• To identify strengths or deficiencies for SRC to support continued product improvement
What / Who / Where:
A sample of 8 SRC BCG's were compared against 8 standard configuration, square-lug AR bolts in MILSPEC BCG's from 4 well known manufacturers (LMT, BCM, Armalite,& FN) . 8 carbine uppers, ( M4 profile 16" chambered 5.56) were used. BCG's of each type were fired in the same uppers as a control. 2 uppers were supplied by SRC and 6 by The Ballistic Edge(my company). For testing purposes, a "rifle" consists as the pairing of one rifle to one BCG. Some were switched in combination at random to create a larger sample size and simulate a larger population of "rifles".
The 10 volunteer firing testers consisted of experienced shooters, intimately familiar with the AR15 / M16 / M4 family of weapons. 2 were retired US Army combat arms veterans, and the balance were SWAT members from 2 local law enforcement agencies who participated for the training and informational value. All participants were thoroughly briefed on exact methodology, standards and procedures to be followed during the test. The test took 6 full days, and was conducted at Watauga Gun Club in Boone, NC.
Test Methodology:
*Pre-test function checks and test firing of test weapons
*Apply media, fire to malfunction
*Use standard malfunction remedial action. Repeat
*Use set failure standard / test to failure (Standards listed below)
*Record all data and actions for analysis
To the greatest extent possible, variables which were not being tested (but could affect data) were controlled, or if uncontrollable, were amortized equally over the data sets.
Start Conditions / Pre- test function checks:
Prior to the beginning of test with mediums each upper receiver and BCG were checked for proper mechanical functioning, and mated with proven reliable lower receivers which also underwent inspection of fire control group and buffer system. Each assembled rifle was test fired with the magazines to be used to check proper functioning before the beginning of testing.
Test media / method of application:
Previous methods of sand/mud testing have generally used participants subjecting weapons to simulated combat conditions crawling, splashing, dragging etc. These methods, while useful for large-scale evaluation, still introduce random variability into the results (one weapon splashed with more mud than another etc). They also potentially create multiple potential failure nodes not related to the part being tested, in this case the bolt and bolt carrier group. To achieve targeted results attributable ONLY to the specific part being evaluated, a test procedure was conceived which only placed the test media directly on the area relevant to the outcome, and in controlled amounts by a prescribed method to hold both user subjectivity and potential variability error to a minimum.
The test media was of 3 primary types which simulate the most common materials encountered in the field environment. The theory in selecting these particular mediums is that they would be the most likely to adhere to metal parts or accumulate without being shed kinetically. There is a assumption that material containing particulates larger than the sizes selected would likely not adhere but be removed by gravity; and secondly that material larger than .015 would cause a mechanical malfunction in ANY operating system and /or possibly cause serious damage to the test weapons.
* Fine particulate dust ("moon dust") - This dust was locally produced by the drying and crushing of illuvial silt from a local watercourse. This material was screened but due to the nature of water-borne settling and deposition this sedimentary material was nearly devoid of large particulates. This media closely simulates the very fine dust found in the Middle East and Southwest Asia.
* Mixed sand - This was a mixture of the moon dust with screened white commercial sand-box sand with average grain size in the .004 to .010 size range. This simulated much of the sand encountered on the ground in desert combat environment.
* Mud slurry of water and fine illuvial silt which has the properties of both migration when wet, and accumulation when dried, but does not contain large enough particulate size to cause binding or jamming from individual grains of material given standard mechanical tolerances. The test medium and methods work on the assumption that large visible amounts of mud would be cleared by the end-user and that the weapon would be still be required to operate with diluted residual.
Application of Test Media:
Each test medium was kept in small buckets at the firing point. After each application of the test medium, the weapon was fired 20 rounds before re-application.
Note: The test was originally designed to re-apply every 100 rounds, but it became obvious that the rate of malfunctions would not yield sufficient information within a reasonable amount of time and within ammunition budgets. The application cycle was changed from 100 to 20 to increase the severity of the operating conditions and accelerate the rate of accumulation to save time and ammunition by inducing malfunctions sooner in the testing cycle.
IT IS UNLIKELY FIELD CONDITIONS WILL EVER REPLICATE THE SEVERITY OF THE CONDITIONS OF THIS TEST.
Moon-dust: The dust was applied by removing the bolt carrier from the upper receiver, placing it bolt-downward into the media to the depth of the front of the bolt carrier, and doing a careful stirring motion so as not to fill the carrier at the cam pin. The BCG with then be given a hard shake, inserted into the receiver and fired.
Mixed Sand: The sand was applied first by splashing sand into the magazine well against the bottom of the BCG, then shaken to allow the excess to fall back out. Then, the bolt was pulled slightly to the rear to create a gap at the front of the bolt carrier simulating a slightly out-of-battery bolt, and sand will be splashed into the gap. Excess was removed by racking the bolt twice before loading and firing.
Mud slurry: Applied as "moon dust" above. Dip, stir, shake, insert, and fire.
Tests and Sample Sizes:
Test firing was done immediately after each application of the test medium, from shoulder-fired weapons. Stoppages were witnessed and recorded real-time to prevent loss of data. a minimum of 4 different upper / BCG's combinations of each type (SRC v Others) were run with each test media. Each consecutive sample block of 100 rounds (5 x 20 round magazines) were tallied until the total sample size was achieved.
"No-Media" Tests:
*Dry Bolt - 1200 Rounds
*Over-lubrication with CLP 991 Rounds
(Performing these tests first provided some break-in period for new bolts before beginning particulate media testing, and was a secondary QC on the weapons)
Media Tests:
* "Moon Dust" - 2,400 Rounds
* Mixed Sand - 1,244 Rounds
* Mud slurry- 1,071 Rounds
Total Test Rounds Fired 6,906
Ammunition:
All ammunition was factory ATK product. Equal amounts of Federal XM-193 and XM-855LC1 were used in the test, usually in alternating magazines of 20 rounds each.
Controlling for variables:
Failures of the weapon system not attributable to the BCG were not relevant to the test and were excluded to the greatest extent possible. The test mediums were confined to the surfaces of the bolt carrier group and the upper receiver where they contact to the best ability of the testers. Care was taken to keep other areas clean which could induce mechanical failure to function and thus isolate the BGC as the critical node. Before each subsequent test sample group, rifle inspections / cleaning were conducted including:
*Chamber and barrel extension lug recess
*Gas tube
*Feed ramp
*Magazine and follower
*Trigger group
* Buffer system
Mechanical Remediation:
Stoppages were cleared (after documentation) by standard method (Tap, rack/mortar, observe, release, tap forward assist) Additional lubrication applied to the bolt / BCG was the only additional remediation allowed unless there was a complete failure of the system which stopped the test. No cleaning of the BCG was performed until a there was a failure stop.
Failure standards:
A standard was decided upon based upon the reasonable measures an end-user might employ, and materials they might have at their disposal in the field to place the weapon back into service without tools or extraordinary measures. These were limited to manual remediation / reduce stoppage drill and direct lubrication of the bolt. The standard for a failure was set as:
• Failure to operate after 3 manual remediation attempts, with additional lubrication allowed after the second manual remediation; or
• Repeated stoppages at a rate that exceed 1 per every 10 shots, or 2 per 20 round magazine.
*Note: Chamber fouling / debris control: Since migration of the test mediums into the chamber could cause stoppages regardless of the bolt / BCG used, a swabbing of the chamber with a wool mop was performed after each failure. If the weapon subsequently returned to functioning, it was allowed to continue and the "failure" was attributed to factors other than bolt/BCG performance and not recorded. The BCG's were fully cleaned and returned to a baseline condition between tests of different media types.
Documentation and Recording:
*Video Recording
* Performance / Failure Data Sheet
A categorized tally sheet was kept to record malfunctions by type, frequency (round count from start and each subsequent application of test media or lubrication). One or two dedicated people served the firing line, recording all data. Firers informed data collectors of round count, and all malfunctions and remedial actions. Periodic inspection and observation notes were made to ensure all weapons used were properly cleaned between tests, and to watch for any weapon-related issues that would affect results.
Note: Any data believed to be influenced by weapon issues not related to the BCG's was removed from the test. An example is a rifle which showed signs of running under-gassed during one test. The data from this rifle was removed, as was the data from its counterpart using the control BCG to keep sample sizes the same.
Categories of results / Data Tracked:
* Rate of malfunctions (total # of malfunctions divided by the total # rounds fired until failure)
* Types of malfunctions - Divided into 2 categories, "Out of battery" (OOB) denoting the failure of the bolt to close and fire minus any feed failures attributable to magazines or Failure to Extract / Eject (FTE/E).
* Effects of accumulation (# shots to first malfunction)
* Manual clearance / remediation results (3 attempts per stoppage)
* Total number of rounds from beginning of test to dead-line failure (3 failed manual remediation attempts) followed by chamber swab which also fails to return rifle to function
The raw numbers from the data collection sheets was entered into a standard template Microsoft Excel spreadsheet for statistical comparison. Results are listed in the order they were performed. Rate of malfunction was used and total numbers of malfunctions are not listed since they can be misunderstood; ie. A rifle which continued to run much longer (positive) before total failure might accrue more total malfunctions before a dead-line stop, thus skewing perception of its actual performance.
__________________________________________________
Results:
Dry Bolt Test: 1200 rounds, 6 Rifles (3 each SRC v MILSPEC)
Rate of Malfunction
SRC .17%
MIL .33%
The difference was negligible, and since the sample of malfunctions was so small, other statistical measures have been excluded.
__________________________________________________
Over-lubed Bolt Test: 991 rounds, 6 Rifles (3 each SRC v MILSPEC)
Rate of Malfunction
SRC .50%
MIL 1.25%
Type of Malfunction
SRC: OOB - 50% FTE/E - 50%
MIL: OOB - 60% FTE/E - 40%
Total Rds to Failure
SRC: No Failures
MIL: No Failures
Remediation Action Average Success Rate
1st time Go
SRC: 100%
MIL: 66.6%
2nd Time Go
SRC: N/A
MIL: 33.3%
Again the sample size of malfunctions was small and no significant difference was observed that warranted statistical analysis.
__________________________________________________
Dust Test: 2,400 rounds, 12 Rifles (6 each SRC v MILSPEC)
Rate of Malfunction
SRC .67%
MIL 1.25%
Type of Malfunction
SRC: OOB - 66.7% FTE/E - 33.3%
MIL: OOB - 73.3% FTE/E - 26.7%
Remedial Action Average Success Rate
1st time Go
SRC: 100%
MIL: 88.57%
2nd time Go
SRC: N/A
MIL: 11.43%
Avg Total Rds to Failure
SRC: No Failures
MIL: No Failures
The dust test was the first test with enough induced malfunctions to give a hint of improved performance of the SRC design over standard MILSPEC profiles with:
46% improvement in average malfunction rate
9% Reduction in out-of-battery stoppage rate
Modest improvement in first-time go clearance rate
Note: There was a slightly higher percentage of FTE/E with the SRC bolt, but this does not mean the total number was higher. This is an artifact of the dropping OOB rate.
___________________________________________________
Sand Test: 1,244 rounds, 12 Rifles (6 each SRC v MILSPEC)
The sand test was the first in which chamber occlusion was controlled for as a variable which could skew results. As such, data is included below which includes whether swabbing the chamber after a dead-line stop allowed the test to continue. Several times during the sand test, migration of the sand into the trigger group caused stoppages. These were not counted into the BCG related data. Lowers were either switched, or the malfunctioning lower was cleaned in a bucket of soapy water, and dried before continuing the test. All rifles failed during the sand test, none made it the allotted 200 rounds per rifle.
Rate of Malfunction
SRC 11.35%
MIL 17.95%
Type of Malfunction
SRC: OOB - 70.77% FTE/E - 29.23%
MIL: OOB - 91.79% FTE/E - 8.21%
Avg rounds to Failure
SRC: 56.5
MIL: 47.17
Remedial Action Average Success Rate
1st time Go
SRC: 50.3%
MIL: 35.09%
2nd time Go
SRC: 26.79%
MIL: 29.22%
3rd time Go
SRC: 9.23%
MIL: 20.7%
Chamber swab Go
SRC 40%
MIL 14.29%
The SRC bolt showed clear advantage in the sand test
58% Improvement in average malfunction rate
23% Reduction in out-of-battery stoppage rate
43% Improvement in first-attempt clearance
20% increase in total rounds to dead-line stop
The SRC bolt however had significantly more failures to extract or eject than MILSPEC (5:1 ratio). The higher "chamber swab go" ratio is specifically because of the greater tendency of the SRC to FTE/E with chamber debris.
___________________________________________________
Mud Test: 1,071 Rounds, 12 Rifles (6 each SRC v MILSPEC)
All rifles in the mud test tested to failure.
Rate of Malfunction
SRC 8.45%
MIL: 15.42%
Type of Malfunction
SRC: OOB - 66.62% FTE/E - 33.38%
MIL: OOB - 85.83% FTE/E - 14.17%
Avg rds to Failure
SRC: 115.17
MIL: 63.17
Remedial Action Average Success Rate
1st time Go
SRC: 65.77%
MIL: 45.83%
2nd time Go
SRC: 15.31%
MIL: 32.87%
3rd time Go
SRC: 7.54%
MIL: 7.87%
Chamber swab Go
SRC 40%
MIL 25%
The most impressive of all of the tests, the SRC showed clear advantage in being able to manage mud on the bolt and move it into spaces vacated by the lug design resulting in:
45% improvement in average malfunction rate
22% Reduction in out-of-battery stoppage rate
44% Improvement in first-attempt clearance
82% increase in total rounds to dead-line stop
These positives are once again slightly marred by the SRC FTE/E rate which again proved to be significantly higher than MILSPEC. (17 : 7).
___________________________________________________
Synopsis:
*The SRC bolt design and finish significantly reduced malfunctions with all media types. The greatest advantage however was seen with mud, where it truly was impressive.
*The performance in sand was also impressive however; real-world advantages of its increased capability in sand will be somewhat mitigated by non-bolt-related types of malfunctions also induced by the sand. The rest of the rifle is likely to experience failure at a rate nearly equal to those caused by the BCG.
* Malfunctions were easier to clear using standard reduce-stoppage clearing methods, presumably due to the lug profile's ability to direct material into unused space in the barrel extension. Material compacted into the recess area by the SRC bolt (anecdotally) seemed to be more compacted and well formed prior to cleaning, which points to efficiency in moving the material aside during functioning, and is likely a major contributing factor to the increased round count to failure observed. The improved ability to clear stoppages in a combat situation represents a significant capability enhancement.
* The NP3 finish on SRC bolts resisted carbon and foreign material accumulation , therefore resulting in more rounds fired before a failure requiring disassembly. The carbon build-up on the bolt was significantly less than standard bolts, particularly during the over-lubrication test. The SRC bolts / BCG were significantly easier to clean.
* No significant wear or broken parts happened to the SRC product during the approximately half of the 6,906 rounds fired, sometimes in highly abrasive media. Some wear and micro-scarring was however more visible on the standard BCG's, and 2 lugs were observed to be chipped. I will not speculate (based on such a small sample) as to whether this observable difference is chance, or attributable to the hardness of S-7 steel and/or NP3 coating although I believe it is possible.
* The SRC bolt showed a tendency towards extraction problems, although based on the total malfunction rate, this issue did not come close to overshadowing the clear advantage in reducing OOB malfunctions. I subsequently replaced the extractor springs in the 4 BCG's I still have in my possession and it seems to have cured the problem. Feedback was sent on the issue and I expect that SRC will immediately remedy the situation.
Opinion: The SRC bolt/ BCG is a solid upgrade to most AR platforms, offering increased functioning and less difficulty of maintenance in austere environments. The rest of the performance enhancements are not to be missed because of an extractor spring which costs a few bucks to replace.
Future evaluation of the SRC product will include accuracy testing by switching the BCG in a highly accurate rifle with the same ammo, and an ongoing durability test as the BCG accumulates wear and tear.
End of report.
+5
The Test Subject:
The Sharps Rifle Company Relia-bolt design claims greater reliability due to the changing of the bolt lug profile to create more area/volume in the lug recess in the barrel extension for foreign material to accumulate without interfering with bolt function; additionally that the modified profile of the lugs are more conducive to moving foreign material aside and maintaining carrier speed and lock-up. Additional features or improvements on the bolt and carrier include NP3 Plus Nickel-Teflon bonded coating for additional dry lubricity; and an enhanced mass-distribution of the bolt carrier aka "Balanced Bolt Carrier" meant to improve cycling.
Before getting started, a full disclosure: I am a full-time industry guy providing training, R&D and design services. As such, I was paid for my time and was provided the ammunition to perform the test under the explicit understanding that the results would be impartial. To do otherwise would compromise both ethics and the data - which aside from potential marketing value, was also intended for future product improvement.
I have no financial interest in the company nor do I receive any compensation or commissions on this product. This was a one-off contract test, and I was paid to generate data, good or bad.. I have told a lot of people that their babies are ugly and am quite comfortable doing so. The following is for informational purposes, and I have received permission from the Sharps Rifle Company to share it. Don't contact me wanting to buy anything, that's not what I do.
Some background... After being contacted by a third party with a request to do the test, I did some internet research. I was immediately intrigued by the SRC design, however I also found some videos of people who had reportedly broken SRC bolts with some commentary that the S-7 steel used was too hard. I asked SRC about this and was informed that S-7 steel is very high tensile, wear resistant and is used in bolts and other parts by reputable manufacturers including Barrett Mfg. They attributed the reported breakage to a particular lot of bolts which had been improperly heat-treated and were run with high-pressure loads in a suppressed carbine (worst case). A recall was issued for the bolts identified. They have since changed the manufacturing process to prevent the issue from recurring and assured me no further problems have been encountered.
Being the natural-born skeptic, I asked for several bolts (8) so that I could have a larger sample group to observe for failure. While lug failures are nothing new (I have seen many failures in Carpenter 158 bolts as well) I still wanted to see if this might be an issue. Up front: There have been no failures of this type to date, with approximately another 15k rounds fired on 4 bolts which I have continued to use in student rifles subsequent to the test I will relate. The reliability test undertaken however, was not designed specifically to attempt to cause material failure by running high-pressure loads through suppressed carbines (the conditions of the previous 2 failures). So, with that caveat, I'll move ahead...
Purpose: The test was undertaken as a statistical direct comparison between the performance of traditional-design MILSPEC bolts / BCG's and the SRC bolt when exposed to variables known or suspected to cause malfunction. These included:
* Dry bolt without lubrication
* Over-lubricated bolt (dripping inside and out with CLP with subsequent migration into the chamber)
*Mud
*Coarse Sand
*Fine Dust
The testing had 2 key goals:
• Providing validation and proof of principle testing on the SRC bolt technology by comparison with traditional / MILSPEC design using test media simulating austere conditions.
• To identify strengths or deficiencies for SRC to support continued product improvement
What / Who / Where:
A sample of 8 SRC BCG's were compared against 8 standard configuration, square-lug AR bolts in MILSPEC BCG's from 4 well known manufacturers (LMT, BCM, Armalite,& FN) . 8 carbine uppers, ( M4 profile 16" chambered 5.56) were used. BCG's of each type were fired in the same uppers as a control. 2 uppers were supplied by SRC and 6 by The Ballistic Edge(my company). For testing purposes, a "rifle" consists as the pairing of one rifle to one BCG. Some were switched in combination at random to create a larger sample size and simulate a larger population of "rifles".
The 10 volunteer firing testers consisted of experienced shooters, intimately familiar with the AR15 / M16 / M4 family of weapons. 2 were retired US Army combat arms veterans, and the balance were SWAT members from 2 local law enforcement agencies who participated for the training and informational value. All participants were thoroughly briefed on exact methodology, standards and procedures to be followed during the test. The test took 6 full days, and was conducted at Watauga Gun Club in Boone, NC.
Test Methodology:
*Pre-test function checks and test firing of test weapons
*Apply media, fire to malfunction
*Use standard malfunction remedial action. Repeat
*Use set failure standard / test to failure (Standards listed below)
*Record all data and actions for analysis
To the greatest extent possible, variables which were not being tested (but could affect data) were controlled, or if uncontrollable, were amortized equally over the data sets.
Start Conditions / Pre- test function checks:
Prior to the beginning of test with mediums each upper receiver and BCG were checked for proper mechanical functioning, and mated with proven reliable lower receivers which also underwent inspection of fire control group and buffer system. Each assembled rifle was test fired with the magazines to be used to check proper functioning before the beginning of testing.
Test media / method of application:
Previous methods of sand/mud testing have generally used participants subjecting weapons to simulated combat conditions crawling, splashing, dragging etc. These methods, while useful for large-scale evaluation, still introduce random variability into the results (one weapon splashed with more mud than another etc). They also potentially create multiple potential failure nodes not related to the part being tested, in this case the bolt and bolt carrier group. To achieve targeted results attributable ONLY to the specific part being evaluated, a test procedure was conceived which only placed the test media directly on the area relevant to the outcome, and in controlled amounts by a prescribed method to hold both user subjectivity and potential variability error to a minimum.
The test media was of 3 primary types which simulate the most common materials encountered in the field environment. The theory in selecting these particular mediums is that they would be the most likely to adhere to metal parts or accumulate without being shed kinetically. There is a assumption that material containing particulates larger than the sizes selected would likely not adhere but be removed by gravity; and secondly that material larger than .015 would cause a mechanical malfunction in ANY operating system and /or possibly cause serious damage to the test weapons.
* Fine particulate dust ("moon dust") - This dust was locally produced by the drying and crushing of illuvial silt from a local watercourse. This material was screened but due to the nature of water-borne settling and deposition this sedimentary material was nearly devoid of large particulates. This media closely simulates the very fine dust found in the Middle East and Southwest Asia.
* Mixed sand - This was a mixture of the moon dust with screened white commercial sand-box sand with average grain size in the .004 to .010 size range. This simulated much of the sand encountered on the ground in desert combat environment.
* Mud slurry of water and fine illuvial silt which has the properties of both migration when wet, and accumulation when dried, but does not contain large enough particulate size to cause binding or jamming from individual grains of material given standard mechanical tolerances. The test medium and methods work on the assumption that large visible amounts of mud would be cleared by the end-user and that the weapon would be still be required to operate with diluted residual.
Application of Test Media:
Each test medium was kept in small buckets at the firing point. After each application of the test medium, the weapon was fired 20 rounds before re-application.
Note: The test was originally designed to re-apply every 100 rounds, but it became obvious that the rate of malfunctions would not yield sufficient information within a reasonable amount of time and within ammunition budgets. The application cycle was changed from 100 to 20 to increase the severity of the operating conditions and accelerate the rate of accumulation to save time and ammunition by inducing malfunctions sooner in the testing cycle.
IT IS UNLIKELY FIELD CONDITIONS WILL EVER REPLICATE THE SEVERITY OF THE CONDITIONS OF THIS TEST.
Moon-dust: The dust was applied by removing the bolt carrier from the upper receiver, placing it bolt-downward into the media to the depth of the front of the bolt carrier, and doing a careful stirring motion so as not to fill the carrier at the cam pin. The BCG with then be given a hard shake, inserted into the receiver and fired.
Mixed Sand: The sand was applied first by splashing sand into the magazine well against the bottom of the BCG, then shaken to allow the excess to fall back out. Then, the bolt was pulled slightly to the rear to create a gap at the front of the bolt carrier simulating a slightly out-of-battery bolt, and sand will be splashed into the gap. Excess was removed by racking the bolt twice before loading and firing.
Mud slurry: Applied as "moon dust" above. Dip, stir, shake, insert, and fire.
Tests and Sample Sizes:
Test firing was done immediately after each application of the test medium, from shoulder-fired weapons. Stoppages were witnessed and recorded real-time to prevent loss of data. a minimum of 4 different upper / BCG's combinations of each type (SRC v Others) were run with each test media. Each consecutive sample block of 100 rounds (5 x 20 round magazines) were tallied until the total sample size was achieved.
"No-Media" Tests:
*Dry Bolt - 1200 Rounds
*Over-lubrication with CLP 991 Rounds
(Performing these tests first provided some break-in period for new bolts before beginning particulate media testing, and was a secondary QC on the weapons)
Media Tests:
* "Moon Dust" - 2,400 Rounds
* Mixed Sand - 1,244 Rounds
* Mud slurry- 1,071 Rounds
Total Test Rounds Fired 6,906
Ammunition:
All ammunition was factory ATK product. Equal amounts of Federal XM-193 and XM-855LC1 were used in the test, usually in alternating magazines of 20 rounds each.
Controlling for variables:
Failures of the weapon system not attributable to the BCG were not relevant to the test and were excluded to the greatest extent possible. The test mediums were confined to the surfaces of the bolt carrier group and the upper receiver where they contact to the best ability of the testers. Care was taken to keep other areas clean which could induce mechanical failure to function and thus isolate the BGC as the critical node. Before each subsequent test sample group, rifle inspections / cleaning were conducted including:
*Chamber and barrel extension lug recess
*Gas tube
*Feed ramp
*Magazine and follower
*Trigger group
* Buffer system
Mechanical Remediation:
Stoppages were cleared (after documentation) by standard method (Tap, rack/mortar, observe, release, tap forward assist) Additional lubrication applied to the bolt / BCG was the only additional remediation allowed unless there was a complete failure of the system which stopped the test. No cleaning of the BCG was performed until a there was a failure stop.
Failure standards:
A standard was decided upon based upon the reasonable measures an end-user might employ, and materials they might have at their disposal in the field to place the weapon back into service without tools or extraordinary measures. These were limited to manual remediation / reduce stoppage drill and direct lubrication of the bolt. The standard for a failure was set as:
• Failure to operate after 3 manual remediation attempts, with additional lubrication allowed after the second manual remediation; or
• Repeated stoppages at a rate that exceed 1 per every 10 shots, or 2 per 20 round magazine.
*Note: Chamber fouling / debris control: Since migration of the test mediums into the chamber could cause stoppages regardless of the bolt / BCG used, a swabbing of the chamber with a wool mop was performed after each failure. If the weapon subsequently returned to functioning, it was allowed to continue and the "failure" was attributed to factors other than bolt/BCG performance and not recorded. The BCG's were fully cleaned and returned to a baseline condition between tests of different media types.
Documentation and Recording:
*Video Recording
* Performance / Failure Data Sheet
A categorized tally sheet was kept to record malfunctions by type, frequency (round count from start and each subsequent application of test media or lubrication). One or two dedicated people served the firing line, recording all data. Firers informed data collectors of round count, and all malfunctions and remedial actions. Periodic inspection and observation notes were made to ensure all weapons used were properly cleaned between tests, and to watch for any weapon-related issues that would affect results.
Note: Any data believed to be influenced by weapon issues not related to the BCG's was removed from the test. An example is a rifle which showed signs of running under-gassed during one test. The data from this rifle was removed, as was the data from its counterpart using the control BCG to keep sample sizes the same.
Categories of results / Data Tracked:
* Rate of malfunctions (total # of malfunctions divided by the total # rounds fired until failure)
* Types of malfunctions - Divided into 2 categories, "Out of battery" (OOB) denoting the failure of the bolt to close and fire minus any feed failures attributable to magazines or Failure to Extract / Eject (FTE/E).
* Effects of accumulation (# shots to first malfunction)
* Manual clearance / remediation results (3 attempts per stoppage)
* Total number of rounds from beginning of test to dead-line failure (3 failed manual remediation attempts) followed by chamber swab which also fails to return rifle to function
The raw numbers from the data collection sheets was entered into a standard template Microsoft Excel spreadsheet for statistical comparison. Results are listed in the order they were performed. Rate of malfunction was used and total numbers of malfunctions are not listed since they can be misunderstood; ie. A rifle which continued to run much longer (positive) before total failure might accrue more total malfunctions before a dead-line stop, thus skewing perception of its actual performance.
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Results:
Dry Bolt Test: 1200 rounds, 6 Rifles (3 each SRC v MILSPEC)
Rate of Malfunction
SRC .17%
MIL .33%
The difference was negligible, and since the sample of malfunctions was so small, other statistical measures have been excluded.
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Over-lubed Bolt Test: 991 rounds, 6 Rifles (3 each SRC v MILSPEC)
Rate of Malfunction
SRC .50%
MIL 1.25%
Type of Malfunction
SRC: OOB - 50% FTE/E - 50%
MIL: OOB - 60% FTE/E - 40%
Total Rds to Failure
SRC: No Failures
MIL: No Failures
Remediation Action Average Success Rate
1st time Go
SRC: 100%
MIL: 66.6%
2nd Time Go
SRC: N/A
MIL: 33.3%
Again the sample size of malfunctions was small and no significant difference was observed that warranted statistical analysis.
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Dust Test: 2,400 rounds, 12 Rifles (6 each SRC v MILSPEC)
Rate of Malfunction
SRC .67%
MIL 1.25%
Type of Malfunction
SRC: OOB - 66.7% FTE/E - 33.3%
MIL: OOB - 73.3% FTE/E - 26.7%
Remedial Action Average Success Rate
1st time Go
SRC: 100%
MIL: 88.57%
2nd time Go
SRC: N/A
MIL: 11.43%
Avg Total Rds to Failure
SRC: No Failures
MIL: No Failures
The dust test was the first test with enough induced malfunctions to give a hint of improved performance of the SRC design over standard MILSPEC profiles with:
46% improvement in average malfunction rate
9% Reduction in out-of-battery stoppage rate
Modest improvement in first-time go clearance rate
Note: There was a slightly higher percentage of FTE/E with the SRC bolt, but this does not mean the total number was higher. This is an artifact of the dropping OOB rate.
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Sand Test: 1,244 rounds, 12 Rifles (6 each SRC v MILSPEC)
The sand test was the first in which chamber occlusion was controlled for as a variable which could skew results. As such, data is included below which includes whether swabbing the chamber after a dead-line stop allowed the test to continue. Several times during the sand test, migration of the sand into the trigger group caused stoppages. These were not counted into the BCG related data. Lowers were either switched, or the malfunctioning lower was cleaned in a bucket of soapy water, and dried before continuing the test. All rifles failed during the sand test, none made it the allotted 200 rounds per rifle.
Rate of Malfunction
SRC 11.35%
MIL 17.95%
Type of Malfunction
SRC: OOB - 70.77% FTE/E - 29.23%
MIL: OOB - 91.79% FTE/E - 8.21%
Avg rounds to Failure
SRC: 56.5
MIL: 47.17
Remedial Action Average Success Rate
1st time Go
SRC: 50.3%
MIL: 35.09%
2nd time Go
SRC: 26.79%
MIL: 29.22%
3rd time Go
SRC: 9.23%
MIL: 20.7%
Chamber swab Go
SRC 40%
MIL 14.29%
The SRC bolt showed clear advantage in the sand test
58% Improvement in average malfunction rate
23% Reduction in out-of-battery stoppage rate
43% Improvement in first-attempt clearance
20% increase in total rounds to dead-line stop
The SRC bolt however had significantly more failures to extract or eject than MILSPEC (5:1 ratio). The higher "chamber swab go" ratio is specifically because of the greater tendency of the SRC to FTE/E with chamber debris.
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Mud Test: 1,071 Rounds, 12 Rifles (6 each SRC v MILSPEC)
All rifles in the mud test tested to failure.
Rate of Malfunction
SRC 8.45%
MIL: 15.42%
Type of Malfunction
SRC: OOB - 66.62% FTE/E - 33.38%
MIL: OOB - 85.83% FTE/E - 14.17%
Avg rds to Failure
SRC: 115.17
MIL: 63.17
Remedial Action Average Success Rate
1st time Go
SRC: 65.77%
MIL: 45.83%
2nd time Go
SRC: 15.31%
MIL: 32.87%
3rd time Go
SRC: 7.54%
MIL: 7.87%
Chamber swab Go
SRC 40%
MIL 25%
The most impressive of all of the tests, the SRC showed clear advantage in being able to manage mud on the bolt and move it into spaces vacated by the lug design resulting in:
45% improvement in average malfunction rate
22% Reduction in out-of-battery stoppage rate
44% Improvement in first-attempt clearance
82% increase in total rounds to dead-line stop
These positives are once again slightly marred by the SRC FTE/E rate which again proved to be significantly higher than MILSPEC. (17 : 7).
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Synopsis:
*The SRC bolt design and finish significantly reduced malfunctions with all media types. The greatest advantage however was seen with mud, where it truly was impressive.
*The performance in sand was also impressive however; real-world advantages of its increased capability in sand will be somewhat mitigated by non-bolt-related types of malfunctions also induced by the sand. The rest of the rifle is likely to experience failure at a rate nearly equal to those caused by the BCG.
* Malfunctions were easier to clear using standard reduce-stoppage clearing methods, presumably due to the lug profile's ability to direct material into unused space in the barrel extension. Material compacted into the recess area by the SRC bolt (anecdotally) seemed to be more compacted and well formed prior to cleaning, which points to efficiency in moving the material aside during functioning, and is likely a major contributing factor to the increased round count to failure observed. The improved ability to clear stoppages in a combat situation represents a significant capability enhancement.
* The NP3 finish on SRC bolts resisted carbon and foreign material accumulation , therefore resulting in more rounds fired before a failure requiring disassembly. The carbon build-up on the bolt was significantly less than standard bolts, particularly during the over-lubrication test. The SRC bolts / BCG were significantly easier to clean.
* No significant wear or broken parts happened to the SRC product during the approximately half of the 6,906 rounds fired, sometimes in highly abrasive media. Some wear and micro-scarring was however more visible on the standard BCG's, and 2 lugs were observed to be chipped. I will not speculate (based on such a small sample) as to whether this observable difference is chance, or attributable to the hardness of S-7 steel and/or NP3 coating although I believe it is possible.
* The SRC bolt showed a tendency towards extraction problems, although based on the total malfunction rate, this issue did not come close to overshadowing the clear advantage in reducing OOB malfunctions. I subsequently replaced the extractor springs in the 4 BCG's I still have in my possession and it seems to have cured the problem. Feedback was sent on the issue and I expect that SRC will immediately remedy the situation.
Opinion: The SRC bolt/ BCG is a solid upgrade to most AR platforms, offering increased functioning and less difficulty of maintenance in austere environments. The rest of the performance enhancements are not to be missed because of an extractor spring which costs a few bucks to replace.
Future evaluation of the SRC product will include accuracy testing by switching the BCG in a highly accurate rifle with the same ammo, and an ongoing durability test as the BCG accumulates wear and tear.
End of report.
+5