Hey guys, it seems we talked GM into considering another barrel for their lineup but Rick is in need of a diagram so he can build it from the original profile.  I know this thread could technically be in either the Retro or A2 section but feel Retro is more appropriate.

Here is a link to the thread on the Industry section where another user brought it up, and GM/Rick chimed in.  Link To GM Barrel Discussion

This barrel is obviously for the pencil profile 14.5 carbines but hopefully made at 14.7" length so we can pin our A1 or A2 birdcage to the end instead of having to use an extended one that throws the look off.  The government profile under the handguards he should already have from other barrels in production, but can someone confirm what the barrel diameter is in front of the front sight base?  And does it have a taper in front of the FSB or is it just a straight profile?  I found a couple mentions in other threads of the diameter being around .570 but it would be nice to get it as close to correct as possible so if anyone has a diagram he can use to build it from that would be awesome - then maybe we can get some nice 14.7" 1-7 twist pencil barrels for all our Retro carbines.

Who knows if this goes well, maybe we can talk him into doing some 11.5"-12.5" carbines as well in 1-7, and maybe even the 20" barrels too since he already offers both 1-12 and 1-14 in the correct profile.  I think this is a great idea and will get a lot of people happy to bring out their credit cards but if I'm wrong feel free to say so.  

If I remember correctly it is .550

"Hopefully" they will be correctly made to the proper length.

Nothing "throws the look off" worse than incorrect external dimensions.

I think they are thinner under the handguards too not just Gov profile, that's what JT dist has and it feels off to me.

I get that, but the majority of us would need an extended flash hider since we aren't filling out paperwork for SBR's on all of our builds and to me the .2" of extra barrel doesn't look nowhere near as bad as an extended flash hider but that's just me.  I would really be happy with either length, just happier with 14.7", and I'd say the majority of others would rather have the .2" of extra barrel over an extended flash hider?  I could be wrong.  Everyone seems to be happy with the 14.7" length of the Brownells ones but they are only available in 1-12, and I'd rather have a GM barrel then one of them anyways.

I figured someone would have the correct dimensions or even a diagram, didn't realize it was so hard to get.  If anyone has an original and wants to provide the info that would be great.  I didn't know they were lighter under the handguard, if true that would make it a little more work on GM, but I'd be happy with a lighter profile.

The only nice thing about the 14.5" is you can properly mount a bayonet on it, not that my range allows a bayonet charge after the mag runs dry.

I can think of one other nice thing- it's the right length.

You don't need a technical drawing to produce the wrong part... just go fail on your own.

A stamp costs $200... it's not 1934 and that's no longer a month's salary in this country. Just do it right.

I am having a hard time thinking that a barrel manufacture, especially a respected one, does not have the proper diagram to build a pretty common barrel configuration?

All anybody has to do is properly search and there are drawings with the proper dimensions on the internet.

FIFY

Probably they do have the right drawing... OP is looking for the wrong one- 14.7 inches or something like that...

You're right, it isn't 1934. But, in 2018, $200 is still a lot of cheese for .2" of barrel length. I have multiple stamps, and have no problem spending the money when I want to. Some guys will throw that down over something so trivial; the majority, won't.

No way.

Guys building up are going to spend half of that on shipping (and transfer) on the various parts that go into a build, then they're going to spend that much again in ammunition the first time they take it out.

Did you buy the wrong length for one of your rifles and now you're hoping other guys will get stuck with a fourteen-point-seven inch barrel with welding that happened on the end of it??

I'd rather pin and weld or silver solder a normal muzzle device on than fork over 200$ to the fed for a tax that shouldn't exist to begin with.

Exactly this! Fug them stoopit mudder fuggers!

They may get one stamp out of me for the GX but I can weasel around on the rest!

This law was passed when the Washington Elites were concerned about the electorate concealing cut down BAR's like Bonnie's "Chopper" and they had watched too many gangster movies and thought silencers were silent.

84 years later and the Washington Elite are STILL ignorant about how firearms work and I can legally conceal an AR pistol with far more firepower than Bonnie's "Chopper".

Take in mind, some states don't allow NFA items

First of all this isn't some big plan I have been working on or anything, as you can tell in the other thread I linked another user posted the idea and I seconded it because I truly believe it is a good idea even if you two guys don't like it for your personal reproductions.  I am not that dumb to search for 14.7" SP1 /CAR barrel dimensions and after looking for 14.5 and 16" ones I can not find an actual diagram but if you can I truly welcome it.  It probably is out there somewhere, I just haven't typed in the right combination of words yet on google search or image search.

Kalash, if the barrel being 14.7" bothers you that much because it isn't correct then I doubt reproduction parts are for you anyways.  This barrel will have a 1-7 twist and I know some of the Colt carbines of the 80-90s came with this twist rate but many of Retro people here would prefer to have the 1-12 so there's a likely chance it's the wrong twist for you as well.  And of course it is going to have Green Mountains rollmarks and will not have the original Colt information on it.  So if you are willing to pay the extra money for the .2" then I figure you are the type of guy that will pay extra to just get the original barrel to start with?  Really no offense meant here, just trying to point out that this barrel may not be right for you but for the majority of people it is likely the best option available.

I am not big on sending the feds paperwork and waiting months and all that crap just to build a carbine up, especially when I want to build multiples.  That isn't to say I won't build an original someday, but I would just get the original barrel if I did.  I'd almost wager that 99% of people if not more who would buy these for a build would not plan on sending it off to the man to get approved.  And then we are left with two options, one of which is to pin/weld an extended A1 flash hider on it which looks really awful to me.  The other option is to just make the barrel 14.7" like many others do and weld on a standard birdcage and have it look almost correct and a little less awful then the extended flash hider.  If it wasn't for that one little hangup I'd be all over a 14.5" but truth is if they make it 14.5" then it is almost useless to me as a retro build and they'd only find their way onto my more modern builds.

Now after all this rambling I found an old thread from almost 15 years ago where a member here tested multiple carbine barrels for dimensions - Click Me

It appears as if the barrel dimensions vary quite a bit.  None of the photos work for me so it is hard to be sure where his points are on the barrel in reference to the A-B-C-D measurements etc.  But it appears as if the front of the barrel by the flash hider has around a .600-.610, the diameter after the FSB is suppose to be around .570-.575 but it varies quite a bit, and of course the gas block journal is .625.  I believe that is his A-B-C, but am unsure what the D is for.  Does anyone have the Black Rifle book?  If so there is suppose to be info on page 352 according to this old post.  And does anyone know if they are lighter under the handguards then government profile?

I'd love to see a 14.7" pencil contour barrel available in a 1/7" twist

Apparently I had the diagram and didn't even know it!

Attached File

Just realized this is a standard M16A1 barrel

I got the brownells 14.7" barrel on a 651 build I build a little bit ago, very well balanced and maybe my favorite shooter.

Thanks for working on this.

I’D like at least one probably two.

Here you go bro, knock yourself out

http://www.specializedarmament.com/%E2%80%94-barrel-assemblies-parts/barrel-assembly-14.5-inch-r0723-carbine/

I have 3 SBR’s. I would never do another one, and I wish I didn’t do them in the first place. Too much regulation, you have to notify them when traveling, you have to have paperwork with you, you can’t lend them out, you have to wait, you have to engrave them, and that’s just the stuff I can thing of offhand. I’ll take two tenths any day.

Exactly, they're spending that money to get the rifle operational, and to the range. A lot of guys aren't going to spend that for .2" of barrel, despite your opinion.

And to answer your asinine question. No. I don't own a .7" anything. 10, 10.5, 10.3, 11.5, 16, 20 in multiples. Lose the attitude, it's a civil discussion.

I'm with you, another big factor in 14.7" vs 14.5".

Ive hated my 651 build for the past 10 yrs because it is on a 16" bbl. After my 607 build, i refuse to thow away another 200.00$ to such an outdated entity. Most all of my 14.5 bbls ive built little extensions, then welded proper muzzle devices ( i agree extended hiders are hideous). I would love to see a 14.7!

Ive hated my 651 build for the past 10 yrs because it is on a 16" bbl. After my 607 build, i refuse to thow away another 200.00$ to such an outdated entity. Most all of my 14.5 bbls ive built little extensions, then welded proper muzzle devices ( i agree extended hiders are hideous). I would love to see a 14.7!

I love my 652 but it has the jamb nut on it and it does bother the snot out of me.

I will have to fix it one day. It bothers me because it's a beautiful rifle but it's just not "right" and looks a bit goofy when I look at it.

I have a Brownells 14.7 Carbine barrel so I may pin/weld it and then chop the 14.5 down to 11.5" and do the extended moderator for an E2 build.

.2" on the barrel is less visually obvious to me than the .2" on an extended A2.

I'm the guy who originally posted this request in the Green Mountain forum.  First, thanks to Wolverine for taking point on this issue and for the others expressing support for a 14.7" pencil barrel WITH a 1x7 twist.

I do live in a State that allows SBRs, but for me, paying $200 for an AFT stamp, doing all the paperwork and waiting a year (+/-) to have a 14.5" barrel isn't my cup of tea where simply pinning a A2 or A1 flash suppressor to a 14.7" is...  I'm not into 100% exact "copies" of Colt M16/AR-15s since A) I don't have the money for original parts and more important, B) its a copy and only a copy...  Which is fine with me and in my "book," a .25" difference is more than fine.

I own several SBRs with really short barrels and to me, it was necessary to go a head and do the paperwork for these SBRs to get what I wanted.

I purchased a couple of Brownells 14.7", 1x12 twist barrels, along with several of their 14.7" M4 barrels for future projects.  To me, being a retired Army Combat Arms (19K) Senior NCO, those extended A2 flash suppressors simply don't look right and will always catch my eye as NOT being right. where "I" don't notice a .25" difference in a barrel's length...  Yes, I'm retarded in my own special ways!!

Hopefully, Green Mountain Barrels will get "hot" with this project or the company that makes the 14.7" barrels for Brownells will jump on this as well. "I" do plan on purchasing 4 to 5 of these barrels.

If nobody has the specs for this type of barrel, how difficult would it be to "reverse engineer" one of Colt original 16" or 14.5" barrels with a "pencil" profile and a 1x7 twist rate AND make the corrections to the production 14.7" length??

ALSO!!!  If Green Mountain Barrels does go a head and make these 14.7" barrels, "I" truly hope that they will put all the barrel's information on the bottom of the barrel AND in the area that's covered up by the handguards.  Again, being retarded, I simply prefer having all the markings on my "Franken-Builds" kept to a minimum and placed in least obvious locations.

Again, I thank everybody for showing interest in these project and I hope that it happens now!!

Yes, forward of the gas block.

Thanks for keeping this alive guys, I haven't been online the past few days.  I posted this on the original thread in the industry section but in case GM reads this first the above diagram is for a modern M4 barrel with government profile that is much heavier out front then the older pencil barrels.  These should look identical to your 20" A1 pencil barrels but just in a shorter 14.7" length.

I gave the dimensions in the other thread for what should work but here goes again just so others can look over and correct anything.  These dimensions should be spot on from everything I have read..

FSB Gas Block Journal - .625
Space between Front Sight Base and muzzle - .570 or .575 either should work - this is a straight profile without taper
Last 1/4" or so raised bump at end of barrel for flash hider to crush against that all lightweight barrels have - .605  (.600-.610 works but .605 is about average)

All of this was for the front part of the barrel

The rear section of the barrel is just your standard government profile taper which like the diagram above, well both diagrams above for both old A1 and new M4 have it at .675 for the part closest to chamber and tapers down to .600 right behind the hump for the gas block.  An easy way to get the measurements would be to check out the 20" A1 barrel and go off whatever it is.  I don't have a good caliper or I would post measurements from 4-5 areas under the handguard but if it's the same person making the barrel print as made the A1 then he can just go from that just scale it down a little.  And make the front portion of the barrel .575.  With an overall barrel length of 14.7", and with either a 1-7 or 1-8 twist.  I am sure most of us here would be happy with either of those twists.