13.7" AR: Pros and Cons

[nate89]

I have been looking into building a 'general purpose' rifle. The purpose is a self defense rifle, a rifle to take to classes, and to practice with. Generally I would be in favor of a 16" gun which I already have), or just going SBR, but because this will be suppressed almost all of the time. I can see an advantage in starting the muzzle device as far back as possible to keep the gun as short as possible while remaining non-NFA. I was originally going to go with a 12.5" barrel, but if I can add just over an inch and go 13.7, add a long muzzle device that will host a suppressor (like a BE Myers or Surefire Warcomp), that seems like a decent trade-off. I am looking at a Surefire mini as the can of choice. My goal is to take the edge off the noise, but I'm not concerned with it being the quietest 5.56 can. More important is POI shift, minimal blowback (i'm a lefty), and durability/reliability while suppressed or unsuppressed.

First: does this sound like a reasonable project?
Should I consider either an adjustable gas block or something like the bootleg adjustable bolt carrier, or will blowback be less of an issue with a short can and longer barrel?
Has anyone built a similar gun and have any suggestions or advice?
Any particular barrels to look at?
If picking between the BE Myers FH or the Warcomp, any preference?

My planned parts list
Upper: Vltor MUR upper
13" Geissele Mk8
Barrel???
Gas Block???
Bootleg bolt carrier with BCM or SOLGW bolt, or if not needed, just a complete BCG from either company

Lower: Rainier ultrmatch lower
BCM LPK
Vltor A5

I am seriously looking at the 1-6 Razor or the 1-6 MIL Trijicon Accupoint. I have a gun with a red dot, and am looking at a LPV to go along with the 'general purpose' idea of useable up close, as well as more practical at distance.

[jethroUSMC]

Rainier offers an Ultra Match and Match in 13.7..

I have one of these barrels and like it, but I have multiple NFA items (SBR's, Suppressors) so I don't worry about meeting non-NFA length requirements.

If keeping it non-NFA is important to you, then you know your choices for muzzle attachment and suppressor options based upon those choices. I personally see zero reason to go with a length shorter that a 16" barrel if you want to stay out of the NFA world the minuscule ounces saved aren't worth it (to me).



I have been looking into building a 'general purpose' rifle. The purpose is a self defense rifle, a rifle to take to classes, and to practice with. Generally I would be in favor of a 16" gun which I already have), or just going SBR, but because this will be suppressed almost all of the time. I can see an advantage in starting the muzzle device as far back as possible to keep the gun as short as possible while remaining non-NFA. I was originally going to go with a 12.5" barrel, but if I can add just over an inch and go 13.7, add a long muzzle device that will host a suppressor (like a BE Myers or Surefire Warcomp), that seems like a decent trade-off. I am looking at a Surefire mini as the can of choice. My goal is to take the edge off the noise, but I'm not concerned with it being the quietest 5.56 can. More important is POI shift, minimal blowback (i'm a lefty), and durability/reliability while suppressed or unsuppressed.

First: does this sound like a reasonable project?
Should I consider either an adjustable gas block or something like the bootleg adjustable bolt carrier, or will blowback be less of an issue with a short can and longer barrel?
Has anyone built a similar gun and have any suggestions or advice?
Any particular barrels to look at?
If picking between the BE Myers FH or the Warcomp, any preference?

My planned parts list
Upper: Vltor MUR upper
13" Geissele Mk8
Barrel???
Gas Block???
Bootleg bolt carrier with BCM or SOLGW bolt, or if not needed, just a complete BCG from either company

Lower: Rainier ultrmatch lower
BCM LPK
Vltor A5

I am seriously looking at the 1-6 Razor or the 1-6 MIL Trijicon Accupoint. I have a gun with a red dot, and am looking at a LPV to go along with the 'general purpose' idea of useable up close, as well as more practical at distance.

[dylank0723]

I have been looking into building a 'general purpose' rifle. The purpose is a self defense rifle, a rifle to take to classes, and to practice with. Generally I would be in favor of a 16" gun which I already have), or just going SBR, but because this will be suppressed almost all of the time. I can see an advantage in starting the muzzle device as far back as possible to keep the gun as short as possible while remaining non-NFA. I was originally going to go with a 12.5" barrel, but if I can add just over an inch and go 13.7, add a long muzzle device that will host a suppressor (like a BE Myers or Surefire Warcomp), that seems like a decent trade-off. I am looking at a Surefire mini as the can of choice. My goal is to take the edge off the noise, but I'm not concerned with it being the quietest 5.56 can. More important is POI shift, minimal blowback (i'm a lefty), and durability/reliability while suppressed or unsuppressed.

First: does this sound like a reasonable project?
Should I consider either an adjustable gas block or something like the bootleg adjustable bolt carrier, or will blowback be less of an issue with a short can and longer barrel?
Has anyone built a similar gun and have any suggestions or advice?
Any particular barrels to look at?
If picking between the BE Myers FH or the Warcomp, any preference?

My planned parts list
Upper: Vltor MUR upper
13" Geissele Mk8
Barrel???
Gas Block???
Bootleg bolt carrier with BCM or SOLGW bolt, or if not needed, just a complete BCG from either company

Lower: Rainier ultrmatch lower
BCM LPK
Vltor A5

I am seriously looking at the 1-6 Razor or the 1-6 MIL Trijicon Accupoint. I have a gun with a red dot, and am looking at a LPV to go along with the 'general purpose' idea of useable up close, as well as more practical at distance.

don't know about a barrel, but the gas block that comes with geissele rails is awesome, easy install and easy to pin


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[nate89]

Good point. I would prefer to use that, unless as adjustable one would be recommended.

[drtywk]

I just built a similar gun on a Ballistic Advantage 14" barrel from Weapon Outfitters and used the BE Meyers/SiCo 249 Omega FH. I wanted something short, but non-NFA to travel to training classes with and this is what I settled on. The 13.7 was too short to run this particular muzzle device on, so the 14 was the way to go. A Trijicon Accupower 1-4x will sit on it as soon as the MI 1.90 mount that I bought shows up. Right now I am running it with an MRO and it is a handy rifle.

My parts list is as follows:

Aero Precision Upper
BA 14" Barrel with BA pinned GB
BE Meyers/SiCo 249ASR FH
BA Nickel Boron BCG
AXTS Raptor Freedom Bone CH
Griffin Armament Low Pro Rigid 13.5" M-Lok Rail


I run it with my SiCo Saker K can.

4246542466

[MOLON AABE]

I did not realize you could attach a Surefire Mini to a BE Meyers muzzle device. What about going with a 16" and using an over barrel suppressor?

Velocitas, Opprimere,
Violentia Operandi

[jpmuscle]

I did not realize you could attach a Surefire Mini to a BE Meyers muzzle device. What about going with a 16" and using an over barrel suppressor?

Velocitas, Opprimere,
Violentia Operandi
You can?

[nickforney]

http://i273.photobucket.com/albums/jj228/nickforney/61A80109-A4C6-4BCE-87C2-2ABB26CE908F.jpg (http://s273.photobucket.com/user/nickforney/media/61A80109-A4C6-4BCE-87C2-2ABB26CE908F.jpg.html)

I like 13.7 guns when pinned with a be meyers. I know there is a mod for surefire cans to work with them and they make saker mounts for them I believe now. A person I know wanted to pin one and drilled through the barrel. He thought it was ruined and said I would take it. Popped it in that pistol AR for use with an AAC 762 sdn. The other gun is the noveske infidel. That barrel has shot good for me and is a favorite.

[Stickman]

The cons are that you are looking at NFA paperwork, or having it affixed to the barrel via pin & weld.

The pros are that you get what you want, the way you want it.

For some odd reason people balk at the 13.7" barrel, but have no problems with a 12.5", 11.5", or 10.3/5". You already know about a loss of velocity, but a 20" has more than an 18", which has more than a 16", and so on. No shock there. Some people also get fussy about the rail, or muzzle device being harder to change. It isn't like your underwear, most people aren't swapping out the rail and muzzle device on a daily basis.

I have a 13.7" .308 simply because I wanted one. I'm not worried about the cries of other people, or what they think, or their hurt feelings.



http://65.media.tumblr.com/9751b3ce51886e6a15ba7d303ac759fe/tumblr_oa6nh6jK9I1rrcg2fo1_1280.jpg

[jpmuscle]

http://i273.photobucket.com/albums/jj228/nickforney/61A80109-A4C6-4BCE-87C2-2ABB26CE908F.jpg (http://s273.photobucket.com/user/nickforney/media/61A80109-A4C6-4BCE-87C2-2ABB26CE908F.jpg.html)

I like 13.7 guns when pinned with a be meyers. I know there is a mod for surefire cans to work with them and they make saker mounts for them I believe now. A person I know wanted to pin one and drilled through the barrel. He thought it was ruined and said I would take it. Popped it in that pistol AR for use with an AAC 762 sdn. The other gun is the noveske infidel. That barrel has shot good for me and is a favorite.
Tell me more about this surefire compatible mount. My Google adventure revealed nothing lol

[nickforney]

It is a monkey bar from unity tactical. I got mine from nightlong industries. Works along side magpul pro sights.

http://i273.photobucket.com/albums/jj228/nickforney/1D4ACC65-32A8-4AC4-9DFC-E5576D0743BC.jpg (http://s273.photobucket.com/user/nickforney/media/1D4ACC65-32A8-4AC4-9DFC-E5576D0743BC.jpg.html)

my dog also refuses to let me take pictures tonight.

[NoveskeFan]

Weapon Outfitters carries a B.E. Meyers 249S which is compatible with Silencerco. Haven't seen a Meyers / Surefire combo. I did a 13.7" with pinned 249F. Nice & tight carbine.

http://i523.photobucket.com/albums/w354/jamesbaezan/Mobile%20Uploads/image_zpssgkhhdxh.jpeg

[MOLON AABE]

It is a monkey bar from unity tactical. I got mine from nightlong industries. Works along side magpul pro sights.

http://i273.photobucket.com/albums/jj228/nickforney/1D4ACC65-32A8-4AC4-9DFC-E5576D0743BC.jpg (http://s273.photobucket.com/user/nickforney/media/1D4ACC65-32A8-4AC4-9DFC-E5576D0743BC.jpg.html)

my dog also refuses to let me take pictures tonight.
We were both, (I believe), referring to SureFire Suppressors, not lights.

Velocitas, Opprimere,
Violentia Operandi

[dylank0723]

when y'all build 14.5 or 13.7 uppers, who is a good person to send the upper to for pinning? about to build one but am not sure how the whole sending an upper off process works


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[drtywk]

My daughters 14.5" was done by Weapon Outfitters, but they don't do any gunsmithing anymore. I've got a local guy now.

[PatrioticDisorder]

when y'all build 14.5 or 13.7 uppers, who is a good person to send the upper to for pinning? about to build one but am not sure how the whole sending an upper off process works


Sent from my iPhone using Tapatalk

Best way to do it is to not pin it, pay the tax to SBR it, wait for the stamp and be done with it.

[sgtbutt]

I built my little Noveske Infidel "clone"using an SMOS GFY build set, Weapon Outfitters Micro MOA Track barrel and KX5, other parts are pretty explanatory. I have always liked the Infidel and when SMOS came out with their GFY it was a no brainer. The appeal to me of a 13.7 gun is that it is short, lighter (can be) and very handy. I ran mine as a pistol and used both BE Meyers and KX5. With a Heavy buffer both devices cycled fine with M855 and Federal 55 grain, I have just a standard Aero GB and this barrel has a mid-length gas system. Needless to say I preferred the KX5 because it directs gas and blast forward. I sent the barreled upper to Rainier Arms for pinning.
I haven't verified but the claim on this particular barrel is that it is designed to have similar velocities you that of a 16 inch gun, I'm stuck on my business trip for another few months but I plan on doing some load development for target and hunting on this and my kid's guns and will be able to chrono this. I plan on taking this out for a little deer and pronghorn slaying if possible next fall, with a 1-6 I found this a very versatile set up.

http://i767.photobucket.com/albums/xx320/sgtbutt/Mobile%20Uploads/20160724_162913_zpsjyfcpjff.jpg (http://s767.photobucket.com/user/sgtbutt/media/Mobile%20Uploads/20160724_162913_zpsjyfcpjff.jpg.html)

[dylank0723]

just curious. on a 14.5, go midlength or carbine length gas?


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[t15]

Significantly more mid lengths than carbine choices.

[nate89]

Thanks for the feedback all. I forgot to mention that I do already have a Saker coming, so that would work with the BE Myers Saker mount. In response to those saying 'just SBR it and be done,' I mentioned that I already have a lower waiting for SBR paperwork right now. This is something different, something I can take out of state (I live about 20 minutes from the border and go to several classes a year and other shooting events outside of the state that I could easily just take this to). I should have clarified that if I went with the surefire can route, I would get the warcomp, or just stick with the saker and use the BE myers.

[CPM]

Best way to do it is to not pin it, pay the tax to SBR it, wait for the stamp and be done with it.

This. I hate the idea of losing velocity for the same or close to the exact same overall length. It doesn't make sense to me.

[nickforney]

We were both, (I believe), referring to SureFire Suppressors, not lights.

Velocitas, Opprimere,
Violentia Operandi

I went looking again and can't find now. I have seen the KAC ones and there was a picture out of the original 249 housing a gemtech can (I believe it was the halo) this would have been a few years ago now though. With the saker mount release it is almost impossible to find in search and they were mods that people had done themselves or had a machinist do.

The concept that it would be better to just get a stamp over pinning a 13.7 is crazy talk. I can dump a pinned 13.7 in my truck and drive just about anywhere without a thought in advance. With the pistol AR it is even easier with carry laws in this country. If you want to suppress it you could double stamp yes but my state is one of several that has no SBR's at all right now. That tide will change across the country over the next few years but one size doesn't fit all. Pin and weld is still a very viable option and there are plenty of great shops out doing it. Seems ADCO has always gotten pretty high marks.

[NongShim]

I'm still scratching my head at how a 13.7+Warcomp is non-NFA when pinned. Surefire states that the length is 2.67". Someone please clarify to me how this combo is 16" because I'm interested but confused.

[Hammer27]

Because 16.37 is more than 16?


I'm still scratching my head at how a 13.7+Warcomp is non-NFA when pinned. Surefire states that the length is 2.67". Someone please clarify to me how this combo is 16" because I'm interested but confused.

[Jwknutson17]

I'm still scratching my head at how a 13.7+Warcomp is non-NFA when pinned. Surefire states that the length is 2.67". Someone please clarify to me how this combo is 16" because I'm interested but confused.

It is not. I'm guessing people don't subtract .625 inches from the barrel length that is the threads. Surefires on 13.7 barrels are still short of the 16. I know because I have a SBR 13.7 with surefire that I properly measured with a dowel rod and it's NOT 16.

[Jwknutson17]

Because 16.37 is more than 16?

This is not correct. Take out the .625 inches. Then add the shim thickness. You will end up short no matter what way you try to work it. Still .2 short.

[NongShim]

This is not correct. Take out the .625 inches. Then add the shim thickness. You will end up short no matter what way you try to work it. Still .2 short.

This is my point. I was pretty sure I could math.

[PatrioticDisorder]

Thanks for the feedback all. I forgot to mention that I do already have a Saker coming, so that would work with the BE Myers Saker mount. In response to those saying 'just SBR it and be done,' I mentioned that I already have a lower waiting for SBR paperwork right now. This is something different, something I can take out of state (I live about 20 minutes from the border and go to several classes a year and other shooting events outside of the state that I could easily just take this to). I should have clarified that if I went with the surefire can route, I would get the warcomp, or just stick with the saker and use the BE myers.

Just get a 16" rifle if you want to take it out of state without filling out a 5320.20. Just search the forum and look how any people regret pinning.

[GH41]

This is not correct. Take out the .625 inches. Then add the shim thickness. You will end up short no matter what way you try to work it. Still .2 short.

Depends on the exact barrel length. I've seen a 249F on a 13.7 and it made 16". Doing the math without barrel and MD in hand says it won't work either. I have no experience with the Warcomp.

[fledge]

To the OP, I think you are on track. For non-NFA, with the saker mounts available, the Meyers with the 13.7" barrel is the shortest configuration I can find. A 14.5" pinned with a SiCo saker mount makes it even longer. And a 16" barrel with saker device makes it an 18".

I don't regret pinning muzzle devices when the device is also a suppressor attachment.

[Stickman]

I threw my BE Meyers on my 14.5", it is a little bit longer than 16", but keeps everything pretty close and doesn't ride under a rail. With the Centurion Arms CMR, it is perfect for barrel coverage (if that is a concern).

http://68.media.tumblr.com/02b3d4338f7f6f84923751fdb8bae5bb/tumblr_o9yksejqi21rrcg2fo1_1280.jpg

[nate89]

It's been awhile since I started this thread, and I figured I would write a quite update for anyone who cares. I did end up building a 13.7 gun, with the following parts

MUR Upper
BCM BCG
Geissele CH and MK14 13" forend
13.7" Ballistic Advantage Barrel, pinned gas block, and gas tube with a double shimmed Dead Air flash hider pinned and welded to ~16.1"
Dead Air Sandman-K lives on this gun
Rainier Ultramatch (ambi) lower
BCM LPK
LAW folder
Vltor A5
Magpul SL-S stock

I added a two-point sling, Trijicon 1-4 in a Larue 1.93 mount, and called it good. Since building it I have shot it in a couple two-gun competitions, took a Sage Dynamics two day carbine class, and basically used it as my go-to rifle since I finished it. The TL;DR: if I had to go back I would pretty much have built it exactly the same. In my experience BA has very reasonable gas port sizes, and this 13.7 is no exception. I originally has a bootleg adjustable bolt in the gun, but found it unnecessary with the Sandman-K, and replaced it with a standard BCM BCG. The gun shoots very well with and without the can.

Although I haven't done any serious accuracy testing, in preparation for the Sage class I had a range session that was primarily getting a solid 200 yard zero, as well as testing for holds at different distances. Out to 300 from prone shooting monopod on the magazine I had no problem keeping a good group on cardboard USPSA targets that I had on hand, and steel out to the same distance was not a problem. I'm sort of interested in exactly what the accuracy is, so hopefully soon I can go out and really get some decent data.

Opportunity cost: myself and pretty much everyone else has a finite budget, so would I give up other barrel lengths to have this gun? I would pick this gun for a 'general purpose' gun over any barrel length that I either currently have or have owned. I have an 11.5" SBR, and like shooting this much better. I know many people regard the 12.5" gun as the optimum 'general purpose' barrel length, but getting a bit longer handguard, and only adding about 1" to the gun that also eliminates any NFA considerations is a good trade for me.

The only real downside I hear from people is "well now you can't change muzzle devices as easy." My response now is "who cares?" I have a 16" BCM upper I bought over 6 years ago with an A2 flash hider on it. I have never had some burning desire to play barbie with the gun and be constantly swapping muzzle devices to the new hotness. Owning Dead Air cans made the decision of muzzle device very easy, and I have never wished I had anything else on it. Maybe after 10K plus rounds through the gun I'll need to replace the barrel or something, and I can do that when the time comes.

The 13.7 gun is shorter and handier, especially with a can, than my 16" guns, while still remaining a title 1 firearm. It also is almost as handy as my 11.5 BCM while having more real estate on the handguard, higher velocity, and smoother shooting. I have been slowly eliminating accessories and guns that I don't use, and getting duplicates of the ones I shoot a lot. My plans in the near future are to build a replica of this upper. Most likely I'll just keep the muzzle device unpinned and use my SBR lower unless I find the need to use this on a standard lower.

If you care about a 13.7 project, hopefully that gives you one person's opinion about the idea.

[jdgiii]

It's been awhile since I started this thread, and I figured I would write a quite update for anyone who cares. I did end up building a 13.7 gun, with the following parts

MUR Upper
BCM BCG
Geissele CH and MK14 13" forend
13.7" Ballistic Advantage Barrel, pinned gas block, and gas tube with a double shimmed Dead Air flash hider pinned and welded to ~16.1"
Dead Air Sandman-K lives on this gun
Rainier Ultramatch (ambi) lower
BCM LPK
LAW folder
Vltor A5
Magpul SL-S stock

I added a two-point sling, Trijicon 1-4 in a Larue 1.93 mount, and called it good. Since building it I have shot it in a couple two-gun competitions, took a Sage Dynamics two day carbine class, and basically used it as my go-to rifle since I finished it. The TL;DR: if I had to go back I would pretty much have built it exactly the same. In my experience BA has very reasonable gas port sizes, and this 13.7 is no exception. I originally has a bootleg adjustable bolt in the gun, but found it unnecessary with the Sandman-K, and replaced it with a standard BCM BCG. The gun shoots very well with and without the can.

Although I haven't done any serious accuracy testing, in preparation for the Sage class I had a range session that was primarily getting a solid 200 yard zero, as well as testing for holds at different distances. Out to 300 from prone shooting monopod on the magazine I had no problem keeping a good group on cardboard USPSA targets that I had on hand, and steel out to the same distance was not a problem. I'm sort of interested in exactly what the accuracy is, so hopefully soon I can go out and really get some decent data.

Opportunity cost: myself and pretty much everyone else has a finite budget, so would I give up other barrel lengths to have this gun? I would pick this gun for a 'general purpose' gun over any barrel length that I either currently have or have owned. I have an 11.5" SBR, and like shooting this much better. I know many people regard the 12.5" gun as the optimum 'general purpose' barrel length, but getting a bit longer handguard, and only adding about 1" to the gun that also eliminates any NFA considerations is a good trade for me.

The only real downside I hear from people is "well now you can't change muzzle devices as easy." My response now is "who cares?" I have a 16" BCM upper I bought over 6 years ago with an A2 flash hider on it. I have never had some burning desire to play barbie with the gun and be constantly swapping muzzle devices to the new hotness. Owning Dead Air cans made the decision of muzzle device very easy, and I have never wished I had anything else on it. Maybe after 10K plus rounds through the gun I'll need to replace the barrel or something, and I can do that when the time comes.

The 13.7 gun is shorter and handier, especially with a can, than my 16" guns, while still remaining a title 1 firearm. It also is almost as handy as my 11.5 BCM while having more real estate on the handguard, higher velocity, and smoother shooting. I have been slowly eliminating accessories and guns that I don't use, and getting duplicates of the ones I shoot a lot. My plans in the near future are to build a replica of this upper. Most likely I'll just keep the muzzle device unpinned and use my SBR lower unless I find the need to use this on a standard lower.

If you care about a 13.7 project, hopefully that gives you one person's opinion about the idea.

Another muzzle device option if you’re running Deadair or any key-mo comparable can is the SOLGW NOX. It is slightly longer than a Deadair flash hider or brake and will bring a 13.7” barrel to 16” without extra shims.

[nate89]

Yes, I have looked into that for the muzzle device on my next 13.7. I know it is quality, but I have also heard of it being more concussive to the sides than the warcomp. Honestly I will probably buy one at least to try out, and if it's not for me I'm not out a ton of money, and I'll hopefully will have learned something. I do like it for the little bit of added length to eliminate the need for a second or thicker shim. I have not had a single issue with alignment with my set-up as is, but a single shim for timing has to be better than the two thick and one thin set-up I have currently.

[kirkland]

Just get a 16" rifle if you want to take it out of state without filling out a 5320.20. Just search the forum and look how any people regret pinning.

But I already have a bunch of 16" inch rifles and I don't want to deal with the paperwork and fees hassle of aquiring an SBR, taking it out of state, transfering it. So it's Pinned and welded or pistol shorties for me!