Pistol Compensators and Reliability; Understanding how to keep your Roland Special running smoothly (Article)

rudukai13

Too Established
Network Support III
#1
C64C78DC-6C1C-49DE-AA80-7426419909B3.jpeg

Compensated handguns are more popular than ever. The unique timing of Chuck’s original Roland Special build combined with the ability of social media to quickly and efficiently spread information ignited a compensated pistol firestorm that has until this point been relatively dormant outside of the competition realm. As is often the case with a rapid expansion in popularity and adoption of a new system, though, mass acceptance has also brought with it several misconceptions and misunderstandings.

While P&S moderators and members have done an excellent job of dispelling some of the more ridiculous myths and claims about pistol comps (Classics like “It’ll blind you at night”, “You’ll injure yourself when shooting from retention”, etc), there is one widespread misunderstanding that I’ve seen continually pop up among even some the more experienced shooters in the community; reliability of compensated pistol systems. That is the topic I hope to address with this post, and hopefully give shooters who are new to pistol compensators a basic understanding of how to keep their compensated pistol running reliably.

Since you’re reading this on the P&S forums, I will assume for the sake of brevity that most of you already know what a compensator is and what it does (for the few who are still unaware, you can read this great article from Guns & Tactics featuring our very own Modern Samurai, Scott Jedlinski; http://www.gunsandtactics.com/rise-of-the-carry-comps).

For the purposes of this discussion, the most important information to understand is how a compensator compensates and what effect that has on the overall system of a semi-auto pistol. Very basically, a compensator harnesses energy from the expanding gasses of a fired round and redirects some of that energy upward, which in turn counteracts the natural tendency for the muzzle to rise during recoil. This same energy from a fired round however is what is responsible and necessary for fully cycling the slide of a semi-auto pistol. The high rate of reliability found in most modern duty pistols (Glock, P320, M&P, etc) is in part due to the careful tuning that goes into making sure the widest possible range of commonly available ammunition provides sufficient energy to fully cycle the pistol. In reality this is a complex interaction between multiple springs inside the gun, the weight of the slide, the ammunition you’re shooting, how clean and lubricated the pistol is, and any myriad other factors that don’t need to be understood for our purposes. A highly over-simplified way to express this interaction is through the following equation;

Cycle = Energy Input / Energy Required to Function

or

Cycle equals the Energy Input divided by the Energy Required to Function

In our simple equation, Cycle is defined as one complete, correct, and successful cycling of the firearm from the time the bullet leaves the barrel to when the slide fully returns to battery on a new live round, ready to fire again. Energy Input is wholly dependent upon the individual round of ammunition being fired, and is a combination of resultant gas pressure and bullet weight. Energy Required to Function is exactly as it sounds - The amount of energy required to overcome all of the springs, friction, resistance, inertia, etc that are present within the pistol itself. Generally speaking, as long as the value of Cycle is greater than 1, the pistol will function reliably. If the value of Cycle for a given round fired dips below 1, malfunctions will become increasingly likely.

When we look at the Cycling of a pistol in this simplified manner, it becomes readily apparent how ammunition choice and modifications to the gun itself can effect reliability. If you use low-power range ammunition (115gr standard-pressure 9mm, for example) in your gun, there is less Energy Input in the system and therefore there must be less Energy Required to Function in order to Cycle. If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to Cycle the pistol.

A compensator though is somewhat unique among modifications that can be done to a pistol, as it generally completes its primary function and effect on the Cycling process in the split second of time between when the bullet is leaving the barrel and when the barrel unlocks from the slide - Before the normal series of mechanical operations involved in the pistol Cycling begins. When adding a compensator to your pistol then, you should not think of it as increasing the Energy Required to Function, but rather immediately decreasing the initial Energy Input.

Since a compensator uses some of the Energy Input that would normally be available to help the slide Cycle, there is less energy remaining to overcome the Energy Required to Function. In our simple equation, the change appears as;

Cycle = (Energy Input - Energy Utilized by the Compensator) / Energy Required to Function

or

Cycle equals the Energy Input minus the Energy Utilized by the Compensator, divided by the Energy Required to Function

In order for the compensated pistol to function reliably, the Energy Input must be sufficient to cover the Energy Utilized by the Compensator AND have enough energy remaining to maintain a Cycle value greater than 1 given the Energy Required to Function (emphasis added cause this is the key take-away from this very lengthy post)

This is why some pistols that ran reliably on low-power range ammo can start to develop reliability issues when running the same ammo after only adding a compensator - Once the compensator has done its job, the remaining Energy Input isn’t sufficient to overcome the Energy Required to Function. Different compensator designs can be more or less effective at redirecting the expanding gas from a fired round, and will therefore rob more or less of the Energy Input.

So, now that we understand how a compensator can effect the reliability of our pistol and why, the question is what can we do to maintain a Cycle value of greater than 1 while still enjoying the positive effects a compensator provides? The answer can be found in adjusting one or more variables from our compensated handgun Cycling equation;

Cycle = (Energy Input - Energy Utilized by the Compensator) / Energy Required to Function

Since we know that the Energy Utilized by the Compensator is a fixed constant based on the design of the compensator, our choices come down to adjusting the values for either the Energy Input or the Energy Required to Function. Adjusting the Energy Required to Function would most often be accomplished by changing recoil spring weights to something lighter than the stock pistol originally came equipped with, however this can very easily upset the delicate balance of the multiple springs present in your pistol that were tuned by the manufacturer to work in conjunction with each other and provide the best reliability possible - inducing even more complex reliability issues than it was meant to solve (just ask an Open division competition shooter about tuning spring weights and watch the resulting PTSD panic attack). Swapping spring weights is not advisable on a gun meant for duty or carry unless the shooter has significant experience and knowledge on how to maintain proper balance of all the springs present in their pistol.

So what’s the best way to ensure reliable Cycling of a compensated pistol without adjusting the Energy Required to Function? Get ready to channel your inner Jeremy Clarkson...

FF9FE154-068D-4C00-8318-BB30F1FC332B.jpeg

Increase the Energy Input! Run hotter ammo than your standard low-power range ammo. This will both help your compensator run more effectively and ensure there’s plenty of power left to overcome the Energy Required to Function and maintain consistent Cycling reliability. Most single- and dual-port compensators meant for duty/carry guns tend to run very reliably on high-pressure, medium grain-weight loads. A good place to start for 9mm is to look at 124gr NATO FMJ loads for range/practice ammo, as these rounds are loaded to about the equivalent of +P gas pressure while still being relatively inexpensive to buy in bulk. For self defense ammo, take your pick of the many 124gr +P modern JHP loads available on the market today.

If you’ve just installed a new compensator on your favorite blaster (or done any modifications to the major function assemblies, for that matter), it would be most ideal to purchase the widest array of commonly available ammo loads possible and run as many through your pistol as you can;

760681F2-AD36-41BD-B626-94A633039631.jpeg

This will generally give you a fairly good indicator of what your absolute minimum Energy Input needs to be based on your specific pistol setup, and you can then enjoy thousands of rounds of (hopefully) malfunction-free shooting with your modified pistol.

—-

Hopefully this post helps some out there better understand the relationship between compensators, ammunition, and reliability in their semi-auto pistols. If anyone notices any corrections that need to be made or has any additional questions, feel free to comment below!
 
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#2
I remember way back in Rudukai’s Project Nemesis thread I recommended 124 Nato Spec. I try to keep things simple. 124 Gr loads as long as they have high enough pressure to get about 1200 FPS work great in my TBRC Comp on a G19.3. 147 Gr loads with enough pressure to just peak above 1000 FPS also work great. I don’t run enough 115 to know what pressure to velocity values work for me.
 

rudukai13

Too Established
Network Support III
#3
I also found in testing that bullets with a grain weight on the heavier side for the caliber (147gr as noted by Mojo for 9mm) tend to function reliably in a comped pistol as well, but they tend to exhibit more muzzle flip than the middle-weight, higher-pressure loads. The reason for this comes down to the two different factors that make up the Energy Input; Gas pressure from the burning powder charge, and bullet weight. Because there tends to be less powder in the case when using heavier grain weight projectiles, there is less gas pressure that can be utilized by the compensator to do its job. These rounds maintain reliable Cycling though due to Newton’s “equal and opposite reaction” law - Because the heavier projectile requires more force to accelerate it down the barrel than a lighter weight projectile, there is an equivalent greater force pushing back on the slide, and this generally is sufficient to overcome the Energy Required to Function
 
#4
View attachment 5963

Compensated handguns are more popular than ever. The unique timing of Chuck’s original Roland Special build combined with the ability of social media to quickly and efficiently spread information ignited a compensated pistol firestorm that has until this point been relatively dormant outside of the competition realm. As is often the case with a rapid expansion in popularity and adoption of a new system, though, mass acceptance has also brought with it several misconceptions and misunderstandings.

While P&S moderators and members have done an excellent job of dispelling some of the more ridiculous myths and claims about pistol comps (Classics like “It’ll blind you at night”, “You’ll injure yourself when shooting from retention”, etc), there is one widespread misunderstanding that I’ve seen continually pop up among even some the more experienced shooters in the community; reliability of compensated pistol systems. That is the topic I hope to address with this post, and hopefully give shooters who are new to pistol compensators a basic understanding of how to keep their compensated pistol running reliably.

Since you’re reading this on the P&S forums, I will assume for the sake of brevity that most of you already know what a compensator is and what it does (for the few who are still unaware, you can read this great article from Guns & Tactics featuring our very own Modern Samurai, Scott Jedlinski; http://www.gunsandtactics.com/rise-of-the-carry-comps).

For the purposes of this discussion, the most important information to understand is how a compensator compensates and what effect that has on the overall system of a semi-auto pistol. Very basically, a compensator harnesses energy from the expanding gasses of a fired round and redirects some of that energy upward, which in turn counteracts the natural tendency for the muzzle to rise during recoil. This same energy from a fired round however is what is responsible and necessary for fully cycling the slide of a semi-auto pistol. The high rate of reliability found in most modern duty pistols (Glock, P320, M&P, etc) is in part due to the careful tuning that goes into making sure the widest possible range of commonly available ammunition provides sufficient energy to fully cycle the pistol. In reality this is a complex interaction between multiple springs inside the gun, the weight of the slide, the ammunition you’re shooting, how clean and lubricated the pistol is, and any myriad other factors that don’t need to be understood for our purposes. A highly over-simplified way to express this interaction is through the following equation;

Cycle = Energy Input - Energy Required to Function

In our simple equation, Cycle is defined as one complete, correct, and successful cycling of the firearm from the time the bullet leaves the barrel to when the slide fully returns to battery on a new live round, ready to fire again. Energy Input is wholly dependent upon the individual round of ammunition being fired, and is a combination of resultant gas pressure and bullet weight. Energy Required to Function is exactly as it sounds - The amount of energy required to overcome all of the springs, friction, resistance, inertia, etc that are present within the pistol itself. Generally speaking, as long as the Energy Input is greater than the Energy Required to Function, the gun will Cycle successfully. Reliability can be thought of as a function of successful individual Cycles over the number of attempted Cycles.

When we look at the Cycling of a pistol in this simplified manner, it becomes readily apparent how ammunition choice and modifications to the gun itself can effect reliability. If you use low-power range ammunition (115gr standard-pressure 9mm, for example) in your gun, there is less Energy Input in the system and therefore there must be less Energy Required to Function in order to Cycle. If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to Cycle the pistol.

A compensator though is somewhat unique among modifications that can be done to a pistol, as it generally completes its primary function and effect on the Cycling process in the split second of time between when the bullet is leaving the barrel and when the barrel unlocks from the slide - Before the normal series of mechanical operations involved in the pistol Cycling begins. When adding a compensator to your pistol then, you should not think of it as increasing the Energy Required to Function, but rather immediately decreasing the initial Energy Input.

Since a compensator uses some of the Energy Input that would normally be available to help the slide Cycle, there is less energy remaining to overcome the Energy Required to Function. In our simple equation, the change appears as;

Cycle = (Energy Input - Energy Utilized by the Compensator) - Energy Required to Function

In order for the compensated pistol to Cycle, the Energy Input must be sufficient to cover the Energy Utilized by the Compensator AND have enough energy remaining to overcome the Energy Required to Function (emphasis added cause this is the key take-away from this very lengthy post)

This is why some pistols that ran reliably on low-power range ammo can start to develop reliability issues when running the same ammo after only adding a compensator - Once the compensator has done its job, the remaining Energy Input isn’t sufficient to overcome the Energy Required to Function. Different compensator designs can be more or less effective at redirecting the expanding gas from a fired round, and will therefore rob more or less of the Energy Input.

So, now that we understand how a compensator can effect the reliability of our pistol and why, the question is what can we do to maintain the best reliability while still enjoying the positive effects a compensator provides? The answer can be found in adjusting one or more variables from our compensated handgun Cycling equation;

Cycle = (Energy Input - Energy Utilized by the Compensator) - Energy Required to Function

Since we know that the Energy Utilized by the Compensator is a fixed constant based on the design of the compensator, our choices come down to adjusting the values for either the Energy Input or the Energy Required to Function. Adjusting the Energy Required to Function would most often be accomplished by changing recoil spring weights to something lighter than the stock pistol originally came equipped with, however this can very easily upset the delicate balance of the multiple springs present in your pistol that were tuned by the manufacturer to work in conjunction with each other and provide the best reliability possible - inducing even more complex reliability issues than it was meant to solve (just ask an Open division competition shooter about tuning spring weights and watch the resulting PTSD panic attack). Swapping spring weights is not advisable on a gun meant for duty or carry unless the shooter has significant experience and knowledge on how to maintain proper balance of all the springs present in their pistol.

So what’s the best way to ensure reliable Cycling of a compensated pistol without adjusting the Energy Required to Function? Get ready to channel your inner Jeremy Clarkson...

View attachment 5964

Increase the Energy Input! Run hotter ammo than your standard low-power range ammo. This will both help your compensator run more effectively and ensure there’s plenty of power left to overcome the Energy Required to Function and maintain consistent Cycling reliability. Most single- and dual-port compensators meant for duty/carry guns tend to run very reliably on high-pressure, medium grain-weight loads. A good place to start for 9mm is to look at 124gr NATO FMJ loads for range/practice ammo, as these rounds are loaded to about the equivalent of +P gas pressure while still being relatively inexpensive to buy in bulk. For self defense ammo, take your pick of the many 124gr +P modern JHP loads available on the market today.

If you’ve just installed a new compensator on your favorite blaster (or done any modifications to the major function assemblies, for that matter), it would be most ideal to purchase the widest array of commonly available ammo loads possible and run as many through your pistol as you can;

View attachment 5965

This will generally give you a fairly good indicator of what your absolute minimum Energy Input needs to be based on your specific pistol setup, and you can then enjoy thousands of rounds of (hopefully) malfunction-free shooting with your modified pistol.

—-

Hopefully this post helps some out there better understand the relationship between compensators, ammunition, and reliability in their semi-auto pistols. If anyone notices any corrections that need to be made or has any additional questions, feel free to comment below!

Wonderful article. Cogent, concise, almost clairvoyant. Thank you for taking the time to explain this. I experienced the delicate balance of energy input (EI) and energy required to function (ERF) in a class recently. My compensated pistol (Shadow systems MR918 with Zev Compensator and RMR09 with 13 lb spring, 124 gr FMJ), which had been working well for 2000 rds and in several previous classes, became a dysfunctional mess when I wore gloves on my supporting hand (30F with wind chill below that). Just the friction of the glove on the slide disrupted the balance of EI and ERF and induced multiple malfunctions. When I took the glove off and consciously placed thumbs forward instead of thumbs up, voila, the malfunctions disappeared.
 
#5
The entire comp thing is a learning process. I’ve been running mine 2 years with no malfunctions since I figured out the 124 Nato Spec and 147+P rounds. That process took about 6 months to get nailed down.
 
#6
I agree with Rudukai that 147 has more muzzle flip than 124 but in my 3 stroke afflicted body, I find it difficult to discern the difference. I shoot both types equally poorly. ;)
Rudukai, are you still using 135 Critical Duty as a carry load? Is the +P version still available? I heard some noise a while back that it was going to be discontinued. I can’t source that info just something I recall hearing or reading somewhere.
 

rudukai13

Too Established
Network Support III
#7
I use 124gr +P Critical Duty as it’s the closest match to the recoil profile of 9mm NATO that’s my designated practice ammo. I did try the 135gr +P when I built the first iteration of the original RS320, but compared to the other 124gr +P loads it just seemed...Off.

Based on a quick search it looks like both the 135gr and 124gr +P Critical Duty loads are still readily available, and to my knowledge there are no plans to discontinue either of them at this time. If Hornady does nix the 124gr load, I’ll find another 124gr +P JHP round that best matches the recoil profile of the 9mm NATO
 
#8
I've had no malfunctions running 124 NATO for practice, and I have found that it feels almost identical to my carry 124 +p Gold Dots with an Agency 2 chamber comp on a gen 5 19 wearing an RMR on an ATEi milled slide. I have run some 115 loads as well and have yet to experience any malfunctions so I may take.your advice and pick up a spread of ammo to see if I can start to induce problems. In the past I had ejection issues on my P320 with aluminum cased federal, curious to see if I get the same with the glock.

On a slightly related note what have y'all found works best for getting carbon and lead build up out of your comp without making a huge mess or taking it off to soak.
 

Clay1

Regular Member
#9
"If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to Cycle the pistol."

I have two comments/questions: I think that some think that adding an Optic like an RMR slows down the cycle of the pistol. I've read recently that the weight of the removed metal from the optic cut exceeds the weight of the optic itself. Please comment on this. In other words the addition of an RMR specifically on a slide that has been milled is in no way detrimental to the cycling of the slide.

Second, a couple of you speak of NATO rounds. Please be more specific on which NATO round you like for training purposes.

Thanks for the efforts on a well thought out piece.
 
#10
I’ve used mostly Winchester Q4318 but have had the same results with PPU Nato Spec. I don’t recall it’s alpha numeric identifier, though. Both types purchased from Sam at SGA Ammo. Never any FTF’s nor any failures of either type of FTE with both types of Nato Spec. I prefer the PPU as if feels a bit hotter to me.

As far as cleaning goes. I don’t take the comp off. I take the whole top end off and stand it up in an inch or so of Slip 725 then scrub away. Works good enough for me. One of these times I’ll snap some before and after pics.
 
#11
Following up on my previous post MEN is also selling Nato Spec 9mm. It is also available thru SG Ammo. S&B I have seen with NATO Spec. Also not surprisingly available at SG Ammo. I’m not in a hurry to try the S&B load but I would like to get my grubby little hands on the MEN version as I’ve heard very good things about their 7.62x51 M-80 ball surplus from someone whose opinion I trust without question.
 

rudukai13

Too Established
Network Support III
#12
"If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to Cycle the pistol."

I have two comments/questions: I think that some think that adding an Optic like an RMR slows down the cycle of the pistol. I've read recently that the weight of the removed metal from the optic cut exceeds the weight of the optic itself. Please comment on this. In other words the addition of an RMR specifically on a slide that has been milled is in no way detrimental to the cycling of the slide.

Second, a couple of you speak of NATO rounds. Please be more specific on which NATO round you like for training purposes.

Thanks for the efforts on a well thought out piece.
In regard to your first question, while there is some variance in how much weight is removed and then added when mounting an optic depending on the mounting solution (direct-mount, adapter plate, dovetail adapter, etc) and the optic itself, the difference in cycling speed of the slide is generally so small as to be negligible from the perspective of the shooter. Generally speaking I would not view the mounting of an optic as detrimental to the ability of the slide to cycle. By referencing it in the article, it was more my intention to present examples of various modifications that can alter the Energy Required to Function variable - Even if the difference might not be noticeable in practice.

As for recommended NATO rounds, the vast majority of the practice rounds I’ve fired have been bulk-purchased Winchester Q4318 and like Mojo I’ve never had any ammunition-induced malfunctions. More recently I’ve had the opportunity to also try Sig’s own E9MMB2PM1750 124gr NATO load, which also functioned flawlessly but is slightly more expensive than the Winchester option
 
#13
"If you make modifications to your pistol such as changing spring weights, milling the slide, or mounting a red dot, the Energy Required to Function can increase or decrease, meaning ammunition of more or less Energy Input may be required to Cycle the pistol."

I have two comments/questions: I think that some think that adding an Optic like an RMR slows down the cycle of the pistol. I've read recently that the weight of the removed metal from the optic cut exceeds the weight of the optic itself. Please comment on this. In other words the addition of an RMR specifically on a slide that has been milled is in no way detrimental to the cycling of the slide.

Second, a couple of you speak of NATO rounds. Please be more specific on which NATO round you like for training purposes.

Thanks for the efforts on a well thought out piece.
I'm also running Winchester Q4318, normally bought in bulk. You can find some pretty good deals at most major retailers. It is noticeably hotter than 115gr anything and is similar feeling to 124+p to me at least.
 

Clay1

Regular Member
#15
I just saw an SG Ammo e-mail where they now have a Magtech Nato Spec round. Listed at 1329 FPS, which seems a bit high. Like 100 FPS high.
Close baby close, to making Major with 9mm Luger. Those velocities are probably with a Thompson Center 14" barrel - ha.

In all seriousness, I wonder what barrel length they took those readings with or what creative journalism they might have used. I'm always skeptical too of factory advertised velocities.
 

rudukai13

Too Established
Network Support III
#18
After continuing to mull this thought over in my head since I first made my initial post, I’ve come to a slightly different formula for describing the energy interactions and have updated the original post accordingly. The original equation left the value for a complete Cycle undefined and vague, which could be a bit confusing. The new equations I’ve updated to are as follows:

For a standard, non-compensated semi-auto pistol:

Cycle = Energy Input / Energy Required to Function

For a comped semi-auto pistol:

Cycle = (Energy Input - Energy Utilized by the Compensator) / Energy Required to Function

In this format, we can better establish a specific value for the Cycle variable that will ensure reliable function of the pistol - that being any value greater than 1. If the value of Cycle dips below 1 for any given round fired, malfunctions become increasingly likely.

Hopefully it’s all still relatively clear and helpful to anyone considering putting a comp on their pistol. Still feel free to ask any questions either here or by PM any time!