11.5" Barrel and other suggestions

[Eager Wine Red Kappa]

Hello All,

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route. I doubt very seriously I will ever run a suppressor, but he is saying he might eventually. He is leaning on me to help him as he has never built an AR or has much armorer experience. Not that I am an expert (hence me being here) but I have built a few and help maintain a few guns for folks. Any helpful suggestions would be appreciated. We are trying to make the lightest weight rifles possible. Budget friendly would be great, but I am aware sometimes you have to "pay to play".

I have picked out the BCM Lightweight Fluted 11.5" barrel for us. Should I lean him towards 12.5" if he is wanting to go suppressed at some point?

Also, does this BCM Barrel ever even come in stock? Because I am beginning to wonder... So what are some alternatives we should consider? Ballistic Advantage? Roscoe?

Ideally all we are trying to change is the barrel, the rail, and the stock. Keeping everything else for now as we move down the road. Speaking of rails. I was under the impression a barrel nut had to be used with the specific rail or the D ring. I am guessing this isn't always the case?

They won't be used for anything realistically outside of 100 yards. We are wanting these for "SHTF/Truck Gun's" to replace our longer rifle that's a burden to us getting in our of trucks an UTVS with.

We will be running red dots with maybe magnifiers.

I believe that's all the information I could give to everyone to try and get some insight. If I missed something please let me know.

Any information would be greatly appreciated. Thanks

 

[Bantam1]

Most handguards that require a special barrel nut will come with the nut. Some also include the wrench, while others will not. Centurion makes handguards that will bolt on around the stock barrel nut, but you need to remove the delta ring. It's another option.

The BCM barrels rarely come back into stock outside of the regular 14.5 mid length gov profile or sometimes the ELW profile. Do research on the barrels. There should be plenty of reviews on 11.5 barrels on the market. Some have better reputations than others. Daniel Defense, Centurion, Criterion etc tend to be good barrels with decent to good accuracy and tend to be gassed well.

Just make sure you get a good tool to hold the upper and barrel like the MI reaction rod. Less chance of damage to the receiver if you use a tool like that.

 

[ut755ln]

Hello All,

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route. I doubt very seriously I will ever run a suppressor, but he is saying he might eventually. He is leaning on me to help him as he has never built an AR or has much armorer experience. Not that I am an expert (hence me being here) but I have built a few and help maintain a few guns for folks. Any helpful suggestions would be appreciated. We are trying to make the lightest weight rifles possible. Budget friendly would be great, but I am aware sometimes you have to "pay to play".

I have picked out the BCM Lightweight Fluted 11.5" barrel for us. Should I lean him towards 12.5" if he is wanting to go suppressed at some point?

Also, does this BCM Barrel ever even come in stock? Because I am beginning to wonder... So what are some alternatives we should consider? Ballistic Advantage? Roscoe?

Ideally all we are trying to change is the barrel, the rail, and the stock. Keeping everything else for now as we move down the road. Speaking of rails. I was under the impression a barrel nut had to be used with the specific rail or the D ring. I am guessing this isn't always the case?

They won't be used for anything realistically outside of 100 yards. We are wanting these for "SHTF/Truck Gun's" to replace our longer rifle that's a burden to us getting in our of trucks an UTVS with.

We will be running red dots with maybe magnifiers.

I believe that's all the information I could give to everyone to try and get some insight. If I missed something please let me know.

Any information would be greatly appreciated. Thanks

Disclaimer, there are a bunch of people on this forum that have built more ARs than I have and that have more experience with varied parts and brands.

1) Why are you trying to go as light as possible? My general experience is that to make it lighter makes it more expensive and more unpleasant to shoot at the same time. A fully kitted M4 just is not that heavy to begin with so I would go with proven reliability and not worry about weight.

2) There is nothing special about the BCM fluted barrel. Criterion makes reasonable barrels including light weight, so doe Roscoe, Ballistic Advantage and others. My experience has been that they are all okay and by that I mean they are fine.

3) I have an LMT Specwar upper that is 12.5" and it really does not do anything any better than my 11.5" Geissele URG-I or my DD MK18 or my HK 416. I don't think that the inch makes much difference except a little more dwell time. I don't know that it makes any difference with suppression.

4) This is kind of a combined comment about barrel nuts, rails and barrels and you can include BCGs and Buffers as well. I am actually picky about rails as I want them rock solid. I actually prefer quad pic rails but do have some mlok rails as well. I tend to mount things like lasers or thermals on the rails and I do not want them shifting. For me, sturdy is better so a normal barrel (or even a heavy profile) plus a robust rail is almost a must.

5) You are greatly underestimating a 11.5" AR. Most shooters with practice can take an 11.5" with a dot and magnifier and add decent ammunition to the equation and you can easily get hits on targets at 500 yards. You just need to practice your holds at various ranges to get the hang of it.

6) This is just me but I actually prefer 16" or longer ARs. My truck gun is a 16" that I installed a Law Tactical Folder on so that it takes up less space.

7) There are a bunch of threads on this subject but "a dot" can mean a lot of things. At this point I have kind of used them all and would go in two directions. If you pay attention and are willing to spend a couple of dollars every six months, I would say go with something like an EOTECH. If you are kind of forgetful and want something that will last a long time (more than a year) go with something like an Aimpoint.

8) If you would like to keep your optics light, you may want to look at something like a 1-6 LPVO instead of dot plus magnifier. If most of your shooting is going to be inside of 200 yards than I would say dot. If you want to extend to 500 then a 1-6 may be a better alternative for you. I have an ACOG fetish and really like the TA02. It is lightweight and pretty bullet proof.

 

[thedude824]

If full time suppression isn’t the intent I would never go below 12.5”. You lose too much velocity and there is a noticeable increase in blast… to me it was unusable.
With regards to barrels I tend to stick with known quality. I love Criterion and they are very affordable. I prefer a little heavier contour so I use the Hybrid. My buddy prefers the lighter offerings so I swapped in a Core for him. As expected it was a big upgrade in terms of balance, accuracy, and appropriate gassing from the Faxon Gunner it replaced. They are also chrome lined so they have a longer service life. You can’t go wrong with Criterion. They also offer an LE/MIL discount

 

[alamo5000]

Hello All,

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route. I doubt very seriously I will ever run a suppressor, but he is saying he might eventually. He is leaning on me to help him as he has never built an AR or has much armorer experience. Not that I am an expert (hence me being here) but I have built a few and help maintain a few guns for folks. Any helpful suggestions would be appreciated. We are trying to make the lightest weight rifles possible. Budget friendly would be great, but I am aware sometimes you have to "pay to play".

I have picked out the BCM Lightweight Fluted 11.5" barrel for us. Should I lean him towards 12.5" if he is wanting to go suppressed at some point?

Also, does this BCM Barrel ever even come in stock? Because I am beginning to wonder... So what are some alternatives we should consider? Ballistic Advantage? Roscoe?

Ideally all we are trying to change is the barrel, the rail, and the stock. Keeping everything else for now as we move down the road. Speaking of rails. I was under the impression a barrel nut had to be used with the specific rail or the D ring. I am guessing this isn't always the case?

They won't be used for anything realistically outside of 100 yards. We are wanting these for "SHTF/Truck Gun's" to replace our longer rifle that's a burden to us getting in our of trucks an UTVS with.

We will be running red dots with maybe magnifiers.

I believe that's all the information I could give to everyone to try and get some insight. If I missed something please let me know.

Any information would be greatly appreciated. Thanks

I don't want to say that accuracy doesn't matter, but it matters a whole lot less with very short barrels at short distances. In other words don't get wrapped around the axle about match grade barrels and such.

While I will readily admit that a short barrel can produce excellent accuracy, but practical use means you won't be shooting from a bench for tiny groups, especially with a red dot.

In other words get something good enough from a decent company. I think my 10.5 is from Ballistic Advantage or something like that. It is really remarkably accurate for what it is used for and it cost like $150 or something.

Also unless you are a very heavy shooter don't worry about a more expensive cold hammer forged barrel. My cheap barrel is good for around 12k to 15k rounds. In the unlikely event that you legally own a machine gun this might not apply, but for the most part most people never shoot enough to wear out a barrel. If you do however shoot through $5,000-$6,000 worth of ammo in one gun you can afford another barrel.

--

Aside from that you would probably want to invest in some buffer springs and buffers of increasing weights. At very least find a friend that will let you borrow a heavier buffer until you figure out just how heavy is heavy enough for your particular rifle.

Short barrel rifles often need to be tuned because of over gassing issues. Usually this is done by introducing stiffer buffer springs and heavier buffers.

 

[alamo5000]

Disclaimer, there are a bunch of people on this forum that have built more ARs than I have and that have more experience with varied parts and brands.

1) Why are you trying to go as light as possible?

I am in agreement with you here. Trying to go ultra light is just going to complicate the whole thing.

2) There is nothing special about the BCM fluted barrel. Criterion makes reasonable barrels including light weight, so doe Roscoe, Ballistic Advantage and others. My experience has been that they are all okay and by that I mean they are fine.

Again, 100% on the money.

3) I have an LMT Specwar upper that is 12.5" and it really does not do anything any better than my 11.5" Geissele URG-I or my DD MK18 or my HK 416. I don't think that the inch makes much difference except a little more dwell time. I don't know that it makes any difference with suppression.

An extra inch can definitely make a difference but it's going to depend on the use case.

5) You are greatly underestimating a 11.5" AR. Most shooters with practice can take an 11.5" with a dot and magnifier and add decent ammunition to the equation and you can easily get hits on targets at 500 yards. You just need to practice your holds at various ranges to get the hang of it.

This is true but often the limits are a matter of practical use. I can hit 300y with my 10.5 but for actual use that's a novelty trick with some limited practical use for most of us average folks. I could probably hit farther than 300 but that's all the space I have at the house.

General use though, shorter guns are meant to be a lot more maneuverable especially in close spaces. This to me generally means it's for shooting and moving, ie more speed less drag. That said there are use cases for all types of setups with a variety of optics. None of them are wrong per se. The trick is setting up the gun for a specific purpose.

 

[kl3309]

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route....

So these are factory carbines? You can't make a rifle into a pistol (well, you can with a tax stamp but why?).

 

[Bluedog82]

So these are factory carbines? You can't make a rifle into a pistol (well, you can with a tax stamp but why?).

Correct, you “technically” can’t take a rifle and make it a pistol, but the other way around is fine. If you care about such things.

 

[Eager Wine Red Kappa]

Most handguards that require a special barrel nut will come with the nut. Some also include the wrench, while others will not. Centurion makes handguards that will bolt on around the stock barrel nut, but you need to remove the delta ring. It's another option.

The BCM barrels rarely come back into stock outside of the regular 14.5 mid length gov profile or sometimes the ELW profile. Do research on the barrels. There should be plenty of reviews on 11.5 barrels on the market. Some have better reputations than others. Daniel Defense, Centurion, Criterion etc tend to be good barrels with decent to good accuracy and tend to be gassed well.

Just make sure you get a good tool to hold the upper and barrel like the MI reaction rod. Less chance of damage to the receiver if you use a tool like that.

Guess I wont be waiting on them any longer then.

I have one of those vise clam shell blocks I got forever ago. I think I got it off brownells way back when and I have a heavy duty vise

 

[Eager Wine Red Kappa]

I don't want to say that accuracy doesn't matter, but it matters a whole lot less with very short barrels at short distances. In other words don't get wrapped around the axle about match grade barrels and such.

While I will readily admit that a short barrel can produce excellent accuracy, but practical use means you won't be shooting from a bench for tiny groups, especially with a red dot.

In other words get something good enough from a decent company. I think my 10.5 is from Ballistic Advantage or something like that. It is really remarkably accurate for what it is used for and it cost like $150 or something.

Also unless you are a very heavy shooter don't worry about a more expensive cold hammer forged barrel. My cheap barrel is good for around 12k to 15k rounds. In the unlikely event that you legally own a machine gun this might not apply, but for the most part most people never shoot enough to wear out a barrel. If you do however shoot through $5,000-$6,000 worth of ammo in one gun you can afford another barrel.

--

Aside from that you would probably want to invest in some buffer springs and buffers of increasing weights. At very least find a friend that will let you borrow a heavier buffer until you figure out just how heavy is heavy enough for your particular rifle.

Short barrel rifles often need to be tuned because of over gassing issues. Usually this is done by introducing stiffer buffer springs and heavier buffers.

I def wont be using it as a bench gun. We are just wanting something lighter and more maneuverable than our current bolt guns and 16" ARs



I have a Spikes Tactical ST-2 laying around and using swap springs for a Damage Industries Enhanced. I am open to other suggestions though.

 

[kl3309]

Hey Fedboys, lookit:

 

[TonyAngel]

Hello All,

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route. I doubt very seriously I will ever run a suppressor, but he is saying he might eventually. He is leaning on me to help him as he has never built an AR or has much armorer experience. Not that I am an expert (hence me being here) but I have built a few and help maintain a few guns for folks. Any helpful suggestions would be appreciated. We are trying to make the lightest weight rifles possible. Budget friendly would be great, but I am aware sometimes you have to "pay to play".

I have picked out the BCM Lightweight Fluted 11.5" barrel for us. Should I lean him towards 12.5" if he is wanting to go suppressed at some point?

Also, does this BCM Barrel ever even come in stock? Because I am beginning to wonder... So what are some alternatives we should consider? Ballistic Advantage? Roscoe?

Ideally all we are trying to change is the barrel, the rail, and the stock. Keeping everything else for now as we move down the road. Speaking of rails. I was under the impression a barrel nut had to be used with the specific rail or the D ring. I am guessing this isn't always the case?

They won't be used for anything realistically outside of 100 yards. We are wanting these for "SHTF/Truck Gun's" to replace our longer rifle that's a burden to us getting in our of trucks an UTVS with.

We will be running red dots with maybe magnifiers.

I believe that's all the information I could give to everyone to try and get some insight. If I missed something please let me know.

Any information would be greatly appreciated. Thanks

You have essentially announced to the world your intention to violate federal law. You can go from a pistol to a rifle, but not the other way around. As for your plans to SBR your rig, ....

If you are going short for the sake of ease of handling and carry, just go with the 11.5. The only reason to go 12.5 is if you need the extra rail space. That extra 1" gets you nothing in terms of real world advantage. All it adds is 30 to 40 fps in velocity, which translates into almost no added range in terms of effective range. What going 12.5 will do is make your rig an inch longer. If you don't mind that, then why not another inch or so and do a 13.9 pin and weld?

The barrel length to velocity ratio is not linear. Going from 10.5 to 11.5 gets you a good jump in velocity, but the major perk is in the increased dwell time. 11.5 to 12.5 gets you a negligible increase in velocity. The next big jump in velocity really doesn't hit until you go from 14.5 to 16". The difference in velocity between an 11.5 and a 16" barrel is about 300 feet per second. That is an appreciable increase that will add an appreciable increase to you max effective range. Much less than that and the increase is only incremental. 11.5 is a good barrel length. 55gr M193 loses something around 325 fps per 100 yards, so going from 11.5 to 16" gets you about another 100 yards.

When you're talking 11.5" barrels, you really don't need to worry too much about barrel profile, unless you are more worried about overall weight than just handling characteristics. An 11.5 is so short that even an HBar doesn't feel heavy because all of the weight is so close to the center of the gun. I'd go for something that will keep up with your shooting style. For fast, high round count shooting, so heavier.

As for fluted vs. non fluted, let me see if I can get this right .... for two barrels of equal length and diameter, the non fluted barrel will be stiffer. For two barrels of equal length and equal weight, the the barrel with the larger diameter will be more rigid.

 

[Bluedog82]

Hey Fedboys, lookit:
View attachment 8656707

….

 

[DeathBeforeDismount]

11.5" with a short can is perfection.

 

[Milspec Longhorn]

I have both. To me the advantage for 12.5 is dwell time for full time suppressed and in theory mid gas

 

[TonyAngel]

11.5" with a short can is perfection.

I don't if you saw that thread here about deals on Armalite barrels, but I grabbed a few 11.5 HBars. I threw one together with the intention of running a Cobalt Kinetics titanium, direct thread can. If you aren't familiar with that can, check it out. It weighs 6 oz. Should make for a nice setup with an overall barrel length of about 15".

I have both. To me the advantage for 12.5 is dwell time for full time suppressed and in theory mid gas

I totally get what you're saying about using a can to add dwell time. I've given it some thought myself with using a Polonium in mind, but I want a lighter rig.

 

[TonyAngel]

Hello All,

Myself and a coworker are changing out our Colt 6920's into pistols or possibly the SBR route. I doubt very seriously I will ever run a suppressor, but he is saying he might eventually. He is leaning on me to help him as he has never built an AR or has much armorer experience. Not that I am an expert (hence me being here) but I have built a few and help maintain a few guns for folks. Any helpful suggestions would be appreciated. We are trying to make the lightest weight rifles possible. Budget friendly would be great, but I am aware sometimes you have to "pay to play".

I have picked out the BCM Lightweight Fluted 11.5" barrel for us. Should I lean him towards 12.5" if he is wanting to go suppressed at some point?

Also, does this BCM Barrel ever even come in stock? Because I am beginning to wonder... So what are some alternatives we should consider? Ballistic Advantage? Roscoe?

Ideally all we are trying to change is the barrel, the rail, and the stock. Keeping everything else for now as we move down the road. Speaking of rails. I was under the impression a barrel nut had to be used with the specific rail or the D ring. I am guessing this isn't always the case?

They won't be used for anything realistically outside of 100 yards. We are wanting these for "SHTF/Truck Gun's" to replace our longer rifle that's a burden to us getting in our of trucks an UTVS with.

We will be running red dots with maybe magnifiers.

I believe that's all the information I could give to everyone to try and get some insight. If I missed something please let me know.

Any information would be greatly appreciated. Thanks

Out of boredom, I re-read this thread. Lots of information flying around. As I mentioned above, 11.5" is a good way to go. It's a solid compromise between compactness and velocity. Don't over think the whole profile thing. It isn't that important with a short barrel. As much as I like BCM stuff, I don't buy their barrels. They are good barrels, but the accuracy just isn't on par with something like a Criterion Hybrid or Geissele barrel, and they cost about the same.

12.5 is an oddball length. It really doesn't get you much in terms of performance. What it does get you is an extra inch or more of rail space, and on some rigs an inch makes a big difference. For suppression, I'd go with 11.5. It's just plain easier to tune with some cans. 12.5, with some cans, will mean way too much dwell time and less tuning window.

As for investing in a bunch of springs and buffers, I dont know about that. Have you seen what springs and buffers cost? I know ... a bunch of guys can pop up swearing to the magic that some Gucci spring worked on their rig. Come on ... it's a spring.

Truth is that the spring rate has very little to do with closed bolt lock time. All it does is alter bolt velocity and, in some cases, lead you to believe that your rifle is tuned correctly, due to ejection pattern, when you are actually still over gassed. There are only two ways to control closed bolt lock time. Either control the gas or increase/decrease buffer weight.

I've found that a gas port size of around .070 is optimal for an 11.5" barrel. Assuming that you get a barrel with an oversized gas port, what I do is get a Yankee Hill Machine suppressor gas block. They are around $20. They come with a very undersized gas hole. I drill it out to the gas port size that I want.

As for springs, a plain Jane carbine spring should do you. I tend to go a few thousand rounds between cleanings, so I run a springco white hot spring to help with chambering when things are dirty. This is not to tune the rifle. This is just to help with chambering reliability.

An 11.5 with a .070 gas port, white hot spring and an H or H2 buffer will be the ticket.

If you want some tuning ability with buffer weights, find yourself an H3 buffer on sale or something. This is usually the cheapest way to find tungsten weights. Then order yourself a few steel weights, from someplace like KAK. To go from an H3 to anything down to a standard buffer weight is as simple as driving out a roll pin and replacing the tungsten weights with steel ones.