14.5” vs 16” carbine rifles

#1
What, if any, is the advantage of using a 14.5” carbine rifle instead of a 16” carbine rifle? And any advantage of a 14.5” with pinned muzzle device? I currently have a 16” carbine and a 10.5” pistol length and don’t like the 10.5” and was wondering about the 14.5”.
 
#2
What, if any, is the advantage of using a 14.5” carbine rifle instead of a 16” carbine rifle? And any advantage of a 14.5” with pinned muzzle device? I currently have a 16” carbine and a 10.5” pistol length and don’t like the 10.5” and was wondering about the 14.5”.
A 16" gun with a carbine length gas system is over gassed because it has too much dwell time, while a 14.5 gun even pinned with a carbine lenght gas system duplicates the operating system of a m4 carbine and works better.

Your gun is a bit shorter with a 14.5, but you do lose some velocity so if your shooting 55 grain ball something to keep in mind. You also get some more muzzle blast
 
#3
A 16" gun with a carbine length gas system is over gassed because it has too much dwell time, while a 14.5 gun even pinned with a carbine lenght gas system duplicates the operating system of a m4 carbine and works better.

Your gun is a bit shorter with a 14.5, but you do lose some velocity so if your shooting 55 grain ball something to keep in mind. You also get some more muzzle blast
Thank you Sir. Very well explained. I thought i wanted a pistol length until i got one. I didn’t do enough research before hand. Now I’m gonna make sure what I’m getting and why i need it.
 

Mike_IA

Member
WARLORD
#4
It’s really a wash between the 2 lengths. The weight difference will be 2” of handguard (if you run a 13” and 15” rail) plus 1.5” of barrel- total weight may be an ounce or 2.

For all practical use, ballistic, and other considerations it’s 6 one way and 1/2 dozen the other way. I have run both lengths in all kinds of situations and they handle the same.

If you have an SBR’d receiver why not do 14.5 midlength. If you don’t just go 16” midlength gas system and call it good. You can make a carbine length 16” gun work properly but it takes some fiddling or a barrel guy that knows what’s up.

Do yourself a favor and never pin and weld. That is the stupidest concept I can think of or see done.
 
#5
I will try and give you my $.02 of opinion, for what it's worth.

The 16" barrel with carbine length gas system has been around for several decades (Colt R6001 was made in 1977). From my recollection the 14.5" system back to guns like the Colt model 651 & 652. Both of these 16" and 14.5" models had carbine length gas systems, and have proven themselves to be reliable.

What you have to take into account are legal issues, and configuration issues of what you are wanting to do or may want to do with the rifle in the future.

The Federal Laws when it comes to rifle barrel length, requires that rifles have to have a 16" barrel or longer to be legal under standard firearms laws. This means that a barrel length of 16", or a barrel length of 14.5" with a 1.5" (or longer) permanently attached flash hider is legal to own. A rifle configured with a 14.5" barrel with a flash hider that is just threaded on, and not permanently attached, by Federal Laws is considered a Class-III NFA weapon, which requires it to be registered as a short barreled rifle.

The next thing to consider is that should you decided to go with a 14.5" barrel length, with a permanently attached flash hider of 1.5" (or longer) to bring the legal length to 16", is that the flash hider is now permanently attached. This permanent attachment only becomes an issue should you need to remove it. It would need to be removed if you wanted to change the gas block or front sight base, change the barrel nut type or free float tube type, add a suppressor mount, etc. In armorer courses we have seen Officers show up with a 14.5" barrel with permanently attached flash hider, that has a free float tube with front sight base, and when they needed to replace a gas tube or re-index the barrel nut, and some have had a hard time doing so as they cannot remove the front sight base off the barrel due to it won't slip over the permanently attached flash hider. Now the barrel could be brought into the machine shop where we could machine the flash hider off and perform the needed work, but the machining cost has to be considered into the value as compared to replacing the barrel.

As for the comment about the 16" being over gassed as compared to the 14.5", this would depend upon how the barrel is made. Also in addition to how the barrel was made, you also have to take into account how the rifle is configured, as the configuration can effect the timing cycle of how fast a gun cycles, and proper cycling for 100% reliability. In advanced armorer courses we measure lots of gas ports and log what we see. If the barrel is made to Military Specs, then a 14.5" & 16" carbine length would have a gas port of .063" on the small end of the spectrum. We see that 14.5" & 16" mid length systems are all over the board, with no standardization of the gas port size, and sometimes location. What we do see is that sometimes manufacturers will open up their gas ports larger than on Milspec barrels. This opening up of the gas port allows more gas to get through, sometimes to make a gun more reliable, and this cycling reliability comes into play especially with some types of lower quality ammunition. The opening up of gas ports also can have a negative effect that can often times in a gun that unlocks earlier in its timing cycle, and a gun that wears itself out faster.

Now for my views of a 16" barrel vs a 14.5" with permanently attached flash hiders, and carbine lenth vs mid-length for Law Enforcement work. What are you gaining or losing? Both systems work reliably as long as the rifle is configured correctly, and quality ammunition is used with reliable magazines. So both can be a good choice. We get Law Enforcement Agencies that ask us which better fits their needs, and I usually answer it with all the information above. Then I lay out reality of how I view the weapon from a Law Enforcement perspective, and that perspective is based on several things. First how long are we probably going to have the weapons, LE changes out handguns on an average of every 7-10 years, but how long do we keep a shoulder weapons can be usually have with an answer of "Forever", which translates to about 25-45 years. Taking into account of how long that we in LE work are going to have that weapon, we need to consider servicing that weapon. Servicing can mean removing gas blocks of front sight bases for changing them or cleaning out gas ports, changing gas tubes, changing hand guard configuration, re-indexing barrel nuts, suppressors, etc. I view the carbine vs mid-length gas, as that the carbine length gas system has been around for about 5-decades and you should always be able to get a carbine length gas tube if you need one. Now compare that to a mid-length system that hasn't been around as long, and isn't standardized for length, so my advise to LE Agencies is that if you are going to go mid-length then purchase a few extra gas tubes to have on hand just in case you ever need them


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
 
#6
I will try and give you my $.02 of opinion, for what it's worth.

The 16" barrel with carbine length gas system has been around for several decades (Colt R6001 was made in 1977). From my recollection the 14.5" system back to guns like the Colt model 651 & 652. Both of these 16" and 14.5" models had carbine length gas systems, and have proven themselves to be reliable.

What you have to take into account are legal issues, and configuration issues of what you are wanting to do or may want to do with the rifle in the future.

The Federal Laws when it comes to rifle barrel length, requires that rifles have to have a 16" barrel or longer to be legal under standard firearms laws. This means that a barrel length of 16", or a barrel length of 14.5" with a 1.5" (or longer) permanently attached flash hider is legal to own. A rifle configured with a 14.5" barrel with a flash hider that is just threaded on, and not permanently attached, by Federal Laws is considered a Class-III NFA weapon, which requires it to be registered as a short barreled rifle.

The next thing to consider is that should you decided to go with a 14.5" barrel length, with a permanently attached flash hider of 1.5" (or longer) to bring the legal length to 16", is that the flash hider is now permanently attached. This permanent attachment only becomes an issue should you need to remove it. It would need to be removed if you wanted to change the gas block or front sight base, change the barrel nut type or free float tube type, add a suppressor mount, etc. In armorer courses we have seen Officers show up with a 14.5" barrel with permanently attached flash hider, that has a free float tube with front sight base, and when they needed to replace a gas tube or re-index the barrel nut, and some have had a hard time doing so as they cannot remove the front sight base off the barrel due to it won't slip over the permanently attached flash hider. Now the barrel could be brought into the machine shop where we could machine the flash hider off and perform the needed work, but the machining cost has to be considered into the value as compared to replacing the barrel.

As for the comment about the 16" being over gassed as compared to the 14.5", this would depend upon how the barrel is made. Also in addition to how the barrel was made, you also have to take into account how the rifle is configured, as the configuration can effect the timing cycle of how fast a gun cycles, and proper cycling for 100% reliability. In advanced armorer courses we measure lots of gas ports and log what we see. If the barrel is made to Military Specs, then a 14.5" & 16" carbine length would have a gas port of .063" on the small end of the spectrum. We see that 14.5" & 16" mid length systems are all over the board, with no standardization of the gas port size, and sometimes location. What we do see is that sometimes manufacturers will open up their gas ports larger than on Milspec barrels. This opening up of the gas port allows more gas to get through, sometimes to make a gun more reliable, and this cycling reliability comes into play especially with some types of lower quality ammunition. The opening up of gas ports also can have a negative effect that can often times in a gun that unlocks earlier in its timing cycle, and a gun that wears itself out faster.

Now for my views of a 16" barrel vs a 14.5" with permanently attached flash hiders, and carbine lenth vs mid-length for Law Enforcement work. What are you gaining or losing? Both systems work reliably as long as the rifle is configured correctly, and quality ammunition is used with reliable magazines. So both can be a good choice. We get Law Enforcement Agencies that ask us which better fits their needs, and I usually answer it with all the information above. Then I lay out reality of how I view the weapon from a Law Enforcement perspective, and that perspective is based on several things. First how long are we probably going to have the weapons, LE changes out handguns on an average of every 7-10 years, but how long do we keep a shoulder weapons can be usually have with an answer of "Forever", which translates to about 25-45 years. Taking into account of how long that we in LE work are going to have that weapon, we need to consider servicing that weapon. Servicing can mean removing gas blocks of front sight bases for changing them or cleaning out gas ports, changing gas tubes, changing hand guard configuration, re-indexing barrel nuts, suppressors, etc. I view the carbine vs mid-length gas, as that the carbine length gas system has been around for about 5-decades and you should always be able to get a carbine length gas tube if you need one. Now compare that to a mid-length system that hasn't been around as long, and isn't standardized for length, so my advise to LE Agencies is that if you are going to go mid-length then purchase a few extra gas tubes to have on hand just in case you ever need them


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
Great info and thank you for the reply. Pretty much answers any question anyone would have on the subject.
 
#7
I will try and give you my $.02 of opinion, for what it's worth.

The 16" barrel with carbine length gas system has been around for several decades (Colt R6001 was made in 1977). From my recollection the 14.5" system back to guns like the Colt model 651 & 652. Both of these 16" and 14.5" models had carbine length gas systems, and have proven themselves to be reliable.

What you have to take into account are legal issues, and configuration issues of what you are wanting to do or may want to do with the rifle in the future.

The Federal Laws when it comes to rifle barrel length, requires that rifles have to have a 16" barrel or longer to be legal under standard firearms laws. This means that a barrel length of 16", or a barrel length of 14.5" with a 1.5" (or longer) permanently attached flash hider is legal to own. A rifle configured with a 14.5" barrel with a flash hider that is just threaded on, and not permanently attached, by Federal Laws is considered a Class-III NFA weapon, which requires it to be registered as a short barreled rifle.

The next thing to consider is that should you decided to go with a 14.5" barrel length, with a permanently attached flash hider of 1.5" (or longer) to bring the legal length to 16", is that the flash hider is now permanently attached. This permanent attachment only becomes an issue should you need to remove it. It would need to be removed if you wanted to change the gas block or front sight base, change the barrel nut type or free float tube type, add a suppressor mount, etc. In armorer courses we have seen Officers show up with a 14.5" barrel with permanently attached flash hider, that has a free float tube with front sight base, and when they needed to replace a gas tube or re-index the barrel nut, and some have had a hard time doing so as they cannot remove the front sight base off the barrel due to it won't slip over the permanently attached flash hider. Now the barrel could be brought into the machine shop where we could machine the flash hider off and perform the needed work, but the machining cost has to be considered into the value as compared to replacing the barrel.

As for the comment about the 16" being over gassed as compared to the 14.5", this would depend upon how the barrel is made. Also in addition to how the barrel was made, you also have to take into account how the rifle is configured, as the configuration can effect the timing cycle of how fast a gun cycles, and proper cycling for 100% reliability. In advanced armorer courses we measure lots of gas ports and log what we see. If the barrel is made to Military Specs, then a 14.5" & 16" carbine length would have a gas port of .063" on the small end of the spectrum. We see that 14.5" & 16" mid length systems are all over the board, with no standardization of the gas port size, and sometimes location. What we do see is that sometimes manufacturers will open up their gas ports larger than on Milspec barrels. This opening up of the gas port allows more gas to get through, sometimes to make a gun more reliable, and this cycling reliability comes into play especially with some types of lower quality ammunition. The opening up of gas ports also can have a negative effect that can often times in a gun that unlocks earlier in its timing cycle, and a gun that wears itself out faster.

Now for my views of a 16" barrel vs a 14.5" with permanently attached flash hiders, and carbine lenth vs mid-length for Law Enforcement work. What are you gaining or losing? Both systems work reliably as long as the rifle is configured correctly, and quality ammunition is used with reliable magazines. So both can be a good choice. We get Law Enforcement Agencies that ask us which better fits their needs, and I usually answer it with all the information above. Then I lay out reality of how I view the weapon from a Law Enforcement perspective, and that perspective is based on several things. First how long are we probably going to have the weapons, LE changes out handguns on an average of every 7-10 years, but how long do we keep a shoulder weapons can be usually have with an answer of "Forever", which translates to about 25-45 years. Taking into account of how long that we in LE work are going to have that weapon, we need to consider servicing that weapon. Servicing can mean removing gas blocks of front sight bases for changing them or cleaning out gas ports, changing gas tubes, changing hand guard configuration, re-indexing barrel nuts, suppressors, etc. I view the carbine vs mid-length gas, as that the carbine length gas system has been around for about 5-decades and you should always be able to get a carbine length gas tube if you need one. Now compare that to a mid-length system that hasn't been around as long, and isn't standardized for length, so my advise to LE Agencies is that if you are going to go mid-length then purchase a few extra gas tubes to have on hand just in case you ever need them


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
So to break it down so I understand, 14.5 has legal issues, both work great, just make sure to get a standard/milspec configuration gun from a reputable manufacturer(colt/BCM/FN/Sons of liberty etc etc)) and you are good to go?

So you mentioned something about gas port sizes varying wildly, what brands or rifles have wide open gas ports or inconsistent gas ports and what is consistent? On the AR-15 modcast the guys there were frustratingly vague I guess in an attempt to not embarrass anyone in the industry.

And would you have a good primer on what effects the cycling speed of a rifle and what is ideal so we can get a better idea of the nuts and bolts behind what makes a gun work and what makes a gun choke?
 
#8
So to break it down so I understand, 14.5 has legal issues, both work great, just make sure to get a standard/milspec configuration gun from a reputable manufacturer(colt/BCM/FN/Sons of liberty etc etc)) and you are good to go?

So you mentioned something about gas port sizes varying wildly, what brands or rifles have wide open gas ports or inconsistent gas ports and what is consistent? On the AR-15 modcast the guys there were frustratingly vague I guess in an attempt to not embarrass anyone in the industry.

And would you have a good primer on what effects the cycling speed of a rifle and what is ideal so we can get a better idea of the nuts and bolts behind what makes a gun work and what makes a gun choke?
IMHO and $.02 worth, I say this when teaching armorer courses: there is a lot of good information and bad information on the internet, in videos, and in books. I moderate on another forum, and try and help out some on forums like this when I can fit it into our already busy schedule. I have seen things come and go in trends like at one time you had to have brand A, B, C, D or E, then it changed to Tier-1 guns, etc. I will say that most manufacturers is capable of producing a quality firearm, and every manufacturer can also produce a lemon on occasion. What is very important, imho, is that when there is a problem, is how the manufacturer deals with it.

In the Law Enforcement arena, we obtain our guns a couple of possible ways. The first being that someone chose that particular weapon because they know exactly what they want. That choice could be based on several different things like, that is what the local gun shop or police supply shop carries, that's what a salesman pushed them into, this is what a neighboring agency has, someone in the Dept read a magazine article and decided that's what they had to have, someone saw a magazine add, and many and most times it is based on lowest bid.

Many municipalities are legally required to put out a bid for their purchase, so when they put out a bid it often times is listed as that they want an AR15 with 16" barrel, semi-auto, flat top upper, with a collapsible stock, which is a very generic description. I always recommend that agencies send one of their staff to an armorer course (Ours our some other one) that will educate them on now only how the gun runs and how to repair it, but to totally understand how to keep the gun running, timing cycles, accessorizing, but very importantly what makes the gun run and what parts are better than others, as by having an educated armorer they can use that information to make a very detailed description on their required bid that they are looking for. It is very surprising that many LE Agencies people that are making the purchase decisions don't have a clue about any of the differences in things like 4140 vs 4150 barrel steel, 6160 vs 7075 aluminum, chrome lined vs chromoly or chrome-vanadium barrels, same plane apertures vs military style, Carpenter 158 bolts and testing processes, etc. So with all that said, what we see in armorer courses is a lot of this is what the department issues me, so our approach when we teach armoring is what can we teach them to make sure they know how to make it run and keep it running, and also tweak or repair things to make the run reliably (Things like gas keys staking, barrels properly indexed, castle nuts staked, timing cycles, parts wear & replacement before breakage when possible, etc).

As for gas port sizes, there are proven milspec configurations that companies like ours use, many based off of the history of the AR15 / M16 weapons system over that last 5 decades of what works. The gas port is a hole in the barrel that the gas pressure travels though, and that gas pressure is what forces either a piston rod to be pushed rearward, or the gas pressure travels back through a gas tube and pushes the bolt carrier to the rear. The size of the gas port regulates how much gas gets though, simply the smaller the hole the less gas passes through, and the larger the hole the more gas that passes through. When we teach advanced armorer courses we measure gas port sizes on barrels, and correlate this timing cycles, trouble shooting, barrel erosion. Barrels erode in numerous places like head space, throat and lead (free bore) erosion, muzzle erosion, and gas port erosion.

I had an agency send 2 Officers to an instructor course with 4 rifles, and they were blowing primers out on about 60% of the rounds fired, where 24 other Officers in the class were using the same ammo (matching lot number) and were not blowing primers on their guns. Upon a greatly detailed inspection it was determined that these 4 rifles had over 40K through them and the gas ports had eroded over .028-.039 from their factory spec, which came down to that these barrels were worn out the the point it was a safety issue (even though they would still headspace withing spec and group were about 1.85"-2.28").

I have noticed that some companies barrels have larger gas ports than what they used to have, of which could be done for many reasons, but I suspect that sometimes it is done for the general public's rifles & ammo (considering that the general public is most likely a much bigger consumer of guns, where the LE/MIL market is very small in comparison). The US Military is using quality ammunition in 5.56 made from a reputable USA manufacturer. Most LE Agencies in the USA are also using quality ammunition in both .223 & 5.56 from a USA reputable manufacturer. What does the bulk of the general public shoot, is most likely answered the cheapest thing they can get their hands on, which is either surplus, or most often it will be some type of imported steel cased ammunition that tends to be lower pressured and not consistent in its quality. Now take into consideration that a rifle maker getting phone calls everyday from the general public who states that their rifle won't run on the lower quality ammo, so I believe that some barrel makers will open up the gas ports to allow more gas to get through so the rifles will run reliably when using the the lower quality ammo, resulting in less customer services issues.

I have also noticed a current trend questions in armorer courses and in internet posts where people have read that if their rifle is ejecting in a certain direction the rifle is under gassed, and if it ejects in another direction it is over gassed. IMHO if you rifle is reliably ejecting the casings, then don't worry about what direction it is ejecting, as the important thing is that your rifle is reliably ejecting the empty casings. What effects the directing it ejects is a multitude of things. Ejection pattern can be tuned with stiffer/softer ejector springs, stiffer/softer extractor systems, buffering system, gas port size, bolt carrier weight, trigger group type & spring strength, ammunition used, weather, altitude, etc. In simple words, as long as your rifle is ejecting the empty cases reliably, then don't worry about what direction.

As for guns running too fast or to slow, I cover this over a 2-day armorer course, so to truly understand this in its entirely I would suggest taking a class, or do a lot of study on your own and you can see patterns if you track plenty of different guns & ammo used. In armorer courses I spend about 1-hour just on timing of guns running too fast or too slow, and how/when/why to adjust it, and what makes things run too fast or slow. The simple answer is if you gun is running too slow, it will generally fail to eject on a consistent basis, so speed up the gun by either opening up the gas system if it's adjustable, or use less buffering resistance. If a gun is unlocking too early, you will either see fail to extracts, or a gun will beat itself up, so you need to slow it down by either closing down an adjustable gas system, or adding more weight / resitance to the buffering system. A reputable manufacturer designs their rifles to run a specific configuration of trigger system, barrel length & gas port (location & size), bolt carrier types, stock type, buffer weight, action spring (buffer spring type), etc. If someone takes a reliable factory configured gun and starts changing out internal parts like adding different buffers or action springs, then they can throw the timing cycle off to where the gun will fail to eject or extract or not feed reliably. In simple words, if your factory rifle works, then don't fix it by changing things out, as you may throw it out of sync.

You will find that ammunition type effects the timing cycle, as .223 is lower pressure as compared to 5.56 Nato which is hotter. That same ammo will also perform different under certain field condition of weather & altitude. What you will see is that ammo will lose velocity in cold weather, and ammo will gain velocity in hot weather. Ammo will also lose velocity at higher altitudes, and gain velocity at lower altitudes.

So after my long winded answer, if you rifle runs reliably then don't mess with it.


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
 
#9
IMHO and $.02 worth, I say this when teaching armorer courses: there is a lot of good information and bad information on the internet, in videos, and in books. I moderate on another forum, and try and help out some on forums like this when I can fit it into our already busy schedule. I have seen things come and go in trends like at one time you had to have brand A, B, C, D or E, then it changed to Tier-1 guns, etc. I will say that most manufacturers is capable of producing a quality firearm, and every manufacturer can also produce a lemon on occasion. What is very important, imho, is that when there is a problem, is how the manufacturer deals with it.

In the Law Enforcement arena, we obtain our guns a couple of possible ways. The first being that someone chose that particular weapon because they know exactly what they want. That choice could be based on several different things like, that is what the local gun shop or police supply shop carries, that's what a salesman pushed them into, this is what a neighboring agency has, someone in the Dept read a magazine article and decided that's what they had to have, someone saw a magazine add, and many and most times it is based on lowest bid.

Many municipalities are legally required to put out a bid for their purchase, so when they put out a bid it often times is listed as that they want an AR15 with 16" barrel, semi-auto, flat top upper, with a collapsible stock, which is a very generic description. I always recommend that agencies send one of their staff to an armorer course (Ours our some other one) that will educate them on now only how the gun runs and how to repair it, but to totally understand how to keep the gun running, timing cycles, accessorizing, but very importantly what makes the gun run and what parts are better than others, as by having an educated armorer they can use that information to make a very detailed description on their required bid that they are looking for. It is very surprising that many LE Agencies people that are making the purchase decisions don't have a clue about any of the differences in things like 4140 vs 4150 barrel steel, 6160 vs 7075 aluminum, chrome lined vs chromoly or chrome-vanadium barrels, same plane apertures vs military style, Carpenter 158 bolts and testing processes, etc. So with all that said, what we see in armorer courses is a lot of this is what the department issues me, so our approach when we teach armoring is what can we teach them to make sure they know how to make it run and keep it running, and also tweak or repair things to make the run reliably (Things like gas keys staking, barrels properly indexed, castle nuts staked, timing cycles, parts wear & replacement before breakage when possible, etc).

As for gas port sizes, there are proven milspec configurations that companies like ours use, many based off of the history of the AR15 / M16 weapons system over that last 5 decades of what works. The gas port is a hole in the barrel that the gas pressure travels though, and that gas pressure is what forces either a piston rod to be pushed rearward, or the gas pressure travels back through a gas tube and pushes the bolt carrier to the rear. The size of the gas port regulates how much gas gets though, simply the smaller the hole the less gas passes through, and the larger the hole the more gas that passes through. When we teach advanced armorer courses we measure gas port sizes on barrels, and correlate this timing cycles, trouble shooting, barrel erosion. Barrels erode in numerous places like head space, throat and lead (free bore) erosion, muzzle erosion, and gas port erosion.

I had an agency send 2 Officers to an instructor course with 4 rifles, and they were blowing primers out on about 60% of the rounds fired, where 24 other Officers in the class were using the same ammo (matching lot number) and were not blowing primers on their guns. Upon a greatly detailed inspection it was determined that these 4 rifles had over 40K through them and the gas ports had eroded over .028-.039 from their factory spec, which came down to that these barrels were worn out the the point it was a safety issue (even though they would still headspace withing spec and group were about 1.85"-2.28").

I have noticed that some companies barrels have larger gas ports than what they used to have, of which could be done for many reasons, but I suspect that sometimes it is done for the general public's rifles & ammo (considering that the general public is most likely a much bigger consumer of guns, where the LE/MIL market is very small in comparison). The US Military is using quality ammunition in 5.56 made from a reputable USA manufacturer. Most LE Agencies in the USA are also using quality ammunition in both .223 & 5.56 from a USA reputable manufacturer. What does the bulk of the general public shoot, is most likely answered the cheapest thing they can get their hands on, which is either surplus, or most often it will be some type of imported steel cased ammunition that tends to be lower pressured and not consistent in its quality. Now take into consideration that a rifle maker getting phone calls everyday from the general public who states that their rifle won't run on the lower quality ammo, so I believe that some barrel makers will open up the gas ports to allow more gas to get through so the rifles will run reliably when using the the lower quality ammo, resulting in less customer services issues.

I have also noticed a current trend questions in armorer courses and in internet posts where people have read that if their rifle is ejecting in a certain direction the rifle is under gassed, and if it ejects in another direction it is over gassed. IMHO if you rifle is reliably ejecting the casings, then don't worry about what direction it is ejecting, as the important thing is that your rifle is reliably ejecting the empty casings. What effects the directing it ejects is a multitude of things. Ejection pattern can be tuned with stiffer/softer ejector springs, stiffer/softer extractor systems, buffering system, gas port size, bolt carrier weight, trigger group type & spring strength, ammunition used, weather, altitude, etc. In simple words, as long as your rifle is ejecting the empty cases reliably, then don't worry about what direction.

As for guns running too fast or to slow, I cover this over a 2-day armorer course, so to truly understand this in its entirely I would suggest taking a class, or do a lot of study on your own and you can see patterns if you track plenty of different guns & ammo used. In armorer courses I spend about 1-hour just on timing of guns running too fast or too slow, and how/when/why to adjust it, and what makes things run too fast or slow. The simple answer is if you gun is running too slow, it will generally fail to eject on a consistent basis, so speed up the gun by either opening up the gas system if it's adjustable, or use less buffering resistance. If a gun is unlocking too early, you will either see fail to extracts, or a gun will beat itself up, so you need to slow it down by either closing down an adjustable gas system, or adding more weight / resitance to the buffering system. A reputable manufacturer designs their rifles to run a specific configuration of trigger system, barrel length & gas port (location & size), bolt carrier types, stock type, buffer weight, action spring (buffer spring type), etc. If someone takes a reliable factory configured gun and starts changing out internal parts like adding different buffers or action springs, then they can throw the timing cycle off to where the gun will fail to eject or extract or not feed reliably. In simple words, if your factory rifle works, then don't fix it by changing things out, as you may throw it out of sync.

You will find that ammunition type effects the timing cycle, as .223 is lower pressure as compared to 5.56 Nato which is hotter. That same ammo will also perform different under certain field condition of weather & altitude. What you will see is that ammo will lose velocity in cold weather, and ammo will gain velocity in hot weather. Ammo will also lose velocity at higher altitudes, and gain velocity at lower altitudes.

So after my long winded answer, if you rifle runs reliably then don't mess with it.


CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
Much appreciated.

Seems like having a factory rifle for the average end user seems like the way to go. Since in my group of friend's Im the gun guy, if anyone asks me what AR to get, I'll just tell them to get a colt 6920 or BCM and a bunch of m193 and some training.

So question, since I and most of the unwashed masses of civilian shooters shoot wolf gold(its cheap and more consistent then steel), where does that place in the pressure/velocity spectrum? From what I understand, its taiwanese spec m193 5.56 but is at the lower end of 5.56 NATO but hotter then most m193. Am I right or way off the mark there.

Also is Lake City xm193 different then military spec ammo? As I keep that sealed away as rainy day ammo
 
#10
Much appreciated.

Seems like having a factory rifle for the average end user seems like the way to go. Since in my group of friend's Im the gun guy, if anyone asks me what AR to get, I'll just tell them to get a colt 6920 or BCM and a bunch of m193 and some training.

So question, since I and most of the unwashed masses of civilian shooters shoot wolf gold(its cheap and more consistent then steel), where does that place in the pressure/velocity spectrum? From what I understand, its taiwanese spec m193 5.56 but is at the lower end of 5.56 NATO but hotter then most m193. Am I right or way off the mark there.

Also is Lake City xm193 different then military spec ammo? As I keep that sealed away as rainy day ammo
I cannot speak for the quality or performance capabilities on Wolf gold ammunition, as I don't shoot it. Federal is local to us, and I generally shoot lots of Federal, Speer, and American Eagle. Federal M193 and XM193 is the same ammunition, the X is added when they have an overrun of Military ammo and need to clear out space, you will also see M855 and XM855, in 308/7.62x51 as well being M80 & XM80.

IMHO a quality built and tuned rifle should perform well with both .223 & 5.56 types of ammunition, as you have to consider that most of the premium hollow point and soft point types of ammunition are generally made in .223 and not 5.56.

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123
 

Arete

Regular Member
#12
Sully knows what he's talking about and we are fortunate to have his contributions.

Having owned both a pinned non NFA 14.5, and 16, barreled rifles, with A2 style muzzle devices, I offer that:
-the difference in overall length is 1 inch; not enough to matter
-when it came time to do barrel work, or mount a suppressor, the pinned 14.5 severely limited my options

Therefore, I recommend AGAINST a pinned 14.5. Go with 16 inch barrel instead.
 
#13
Excellent responses by Sully.

I used a Pinned 14.5" mid length upper on my Patrol Rifle for a couple of years. It was an excellent upper Until I wanted to change out the KeyMod hand guard for one in M-Lok... It was easier to just sell off the entire upper and start over from scratch.

I now only use 16" uppers, for this reason. As an LEO patrol rifle, I really didn't notice a difference in maneuvering a gun with the extra 1.5" of barrel. With my longer arms, I appreciate the ability to go from a 13" rail to a 15" rail.
 
#15
My first build and current work horse "do-all" rifle is centered around a BCM 14.5" mid Length upper with a pinned Silencer Co ASR flash hider on a non-NFA lower. I've got it paired with a BCM H2 buffer and it is one of the softest shooting rifles I've had the pleasure of shooting. I've had the muzzle device re-pinned three times and it's never really been that huge a nuisance (personal opinion) for me.

That being said, I also have an SBR registered lower so once this barrel goes (which probably wont be for a while) I'll likely just get a non-pinned 14.5" and throw it on the SBR lower and get a 16" upper for the non-NFA upper.

I really do think it comes down to personal preference. I had the 14.5" pinned for about 2 years before SBR'ing the other lower and I've never really had a moment where I went, "damn. I wish I had just gotten a 16inch barrel."
 
#17
Did you ever have a moment where you were glad for the 14.5" instead of a 16"?
I've never had a 16" upper so I can't speak to that. All I can say is that when I was looking to purchase it I spent a lot of time reading threads on 14.5" vs 16" and I don't have any regrets going 14.5". Maybe if/when I get a 16" upper in the future I will be able to answer that question better since I'll be able to handle both in similar environments.
 

RustyM92

Amateur
WARLORD
#18
My experience with CQB is limited to using a standard M4, and while the 14.5" barrel (which is something like 15.75" with an A2) isn't the most ideal, it's adequate enough for inside work. Personally, I don't find a 16" barrel (which with an A2 is now just slightly over 17.25") to be much more inconvenient inside. Where I can personally see a problem with a 16" barrel is once you start adding Surefire or other muzzle devices that are over 2" in length, and now the barrel starts pushing past that 18" mark which starts to get a little unwieldy inside a house. Has this been anyone's experience, or do you find the difference to be marginal?