Discussion of how to get an 8.5" Barrel SBR AR15 to 29" OAL

thai · Dec 30, 2015

I hate gathering parts by osmosis! I don't have the patience, and am too scattered brain to remember what I have ordered and what I still need. I prefer to just order everything I need while it is still fresh on my mind. I have all my lowers built, uppers sitting on handgun buffer tubed lowers, and Aimpoint H1's I got on Black Friday at $250 discount, and a couple suppressors in jail.

Just waiting for stamps. I will have engraving done on same day I get my SBR'S stamps and suppressors, providing ATF can get their act together and approve everything at the same time without quadrupling their work load and redundancy.

Yeah right! :sarcasm:

, I can only dream.

fabsroman · Dec 30, 2015

thai said:
I hate gathering parts by osmosis! I don't have the patience, and am too scattered brain to remember what I have ordered and what I still need. I prefer to just order everything I need while it is still fresh on my mind. I have all my lowers built, uppers sitting on handgun buffer tubed lowers, and Aimpoint H1's I got on Black Friday at $250 discount, and a couple suppressors in jail.

Just waiting for stamps. I will have engraving done on same day I get my SBR'S stamps and suppressors, providing ATF can get their act together and approve everything at the same time without quadrupling their work load and redundancy.

Yeah right! , I can only dream.

Not only would my wife have a heart attack if I did something like that, but it would hurt my stomach too much too. It kills me to see large outflows of money. Plus, there would be way too many parts just sitting around all over the place waiting for me to put them all together.

SneakySh0rty · Dec 30, 2015

YMMV...but here are my measurements.

10.5" Rainier Ultramatch Barrel and stock is ACS-L with the .70" and VLTOR 7 POS buffer tube

you can see what it measures at WITHOUT the muzzle brake. Minus 2 inches for a 8.5" and :tdown:

Now is the ATF going to go around with rulers? doubt it, but I just had to share my results.

fabsroman · Dec 30, 2015

SneakySh0rty said:
YMMV...but here are my measurements.

10.5" Rainier Ultramatch Barrel and stock is ACS-L with the .70" and VLTOR 7 POS buffer tube

you can see what it measures at WITHOUT the muzzle brake. Minus 2 inches for and 8.5" and Now is the ATF going to go around with rulers? doubt it, but I just had to share my results.

The ATF isn't the only one that can enforce the 29" OAL law. MSP, HoCo, Park Police, and almost any other police department in Maryland can enforce it. I can live with a 10.5" barrel on the .300 BLK, a 11.3" on the 5.56, and a 12" on the .458 SOCOM.

The risk and penalties versus the reward of shaving two more inches off a barrel, even though the risk might be ever so slight, just isn't worth it. Even if I don't go to prison, I probably would lose my professional licenses.

Edit to add: Thanks for the pictures though. Think I am going to put all of this together with the help of my FFL.

SneakySh0rty · Dec 30, 2015

fabsroman said:
The ATF isn't the only one that can enforce the 29" OAL law. MSP, HoCo, Park Police, and almost any other police department in Maryland can enforce it. I can live with a 10.5" barrel on the .300 BLK, a 11.3" on the 5.56, and a 12" on the .458 SOCOM.

The risk and penalties versus the reward of shaving two more inches off a barrel, even though the risk might be ever so slight, just isn't worth it. Even if I don't go to prison, I probably would lose my professional licenses.

Edit to add: Thanks for the pictures though. Think I am going to put all of this together with the help of my FFL.

I mean a 9" will work, I didn't take a picture with the 9" barrel upper cause I didnt feel like taking off the muzzle brake or handguards. Though 10.5 should be safe for most stock configurations (but dont quote me on that

). One of my other SBRs will rock a normal MOE or CTR stock, once i get around to ordering one. lol. But once i do, if necessary ill post up measurements for that one as well.

bobthefisher · Jan 8, 2016

I have a pre-ban 7.5" barrel Adams Arms AR-15 SBR and a pre-ban 11" barrel DS Arms FAL SBR. Both are a bit too short for their respective calibers, as they're VERY harsh on the blast baffle of any suppressor. Don't get me wrong they're fun as hell to shoot, but those really short barrels do have their negatives, and killing a suppressor is one of them. The AR-15 is rocking a SilencerCo Specwar 556 (stellite) and the FAL usually has the Gemtech Quicksand Titanium. Even with those hard materials, there can be significant blast baffle erosion. If I had to do it all over again, I would probably have the barrels at 10.5 inch for the AR-15 and a 13-14 inch for the FAL.

Just something to think about.

Hawkeye · Jan 8, 2016

bobthefisher said:
I have a pre-ban 7.5" barrel Adams Arms AR-15 SBR and a pre-ban 11" barrel DS Arms FAL SBR. Both are a bit too short for their respective calibers, as they're VERY harsh on the blast baffle of any suppressor. Don't get me wrong they're fun as hell to shoot, but those really short barrels do have their negatives, and killing a suppressor is one of them. The AR-15 is rocking a SilencerCo Specwar 556 (stellite) and the FAL usually has the Gemtech Quicksand Titanium. Even with those hard materials, there can be significant blast baffle erosion. If I had to do it all over again, I would probably have the barrels at 10.5 inch for the AR-15 and a 13-14 inch for the FAL.

Just something to think about.

That's totally worthwhile.

In my specific case, I built a .300BLK pistol with an 8.5" barrel, which is the length that the caliber was intended for, so the powder burn is complete at that point and there's no crazy blast like there is with a really short 5.56 or 7.62.

I submitted my Form 1 for this before Christmas, so we'll see when it comes back.

Hawkeye · Mar 29, 2016

Ok:

I finally finished my 8.5" .300BLK SBR build, and while I did that I did some very careful measuring. Forgive the length and nit-pickiness of this post, but I wanted it to serve as a possible guide to anyone else in MD who might need or want to attempt an 8.5" barrel SBR without a pinned muzzle device.

Note that at no time did I assemble anything that would be illegal in Maryland, but these measurements are very precise. They are also valid for MY rifle, with MY barrel and parts. Yours may differ, and you have to figure things out for your own case. Reading my experiences doesn't absolve you from possibly breaking the law.

Now that that's out of the way...

I have an 8.5" .300BLK barrel from Palmetto State Armory. Measuring the barrel length as prescribed by the ATF (close the bolt, and insert a rod from the muzzle until it touches the bolt face. Mark the end of the barrel on the rod, and measure from the tip to that mark) I get a measurement of 8 9/16". Please note that again, as prescribed by the ATF, I removed my non-permanent muzzle device to get all measurements in this post.

In an attempt to get the maximum OAL, I also installed a BCM "Intermediate Length" 8 position A5 buffer tube kit as found here. This is an A5 tube, which is about 3/4" longer than a standard carbine tube.

Then I looked at stocks. I really wanted to use the BCM Gunfighter stock, because it's lightweight and VERY strong. Unfortunately, it's also short. I also tried a VLTOR eMod that I had at home. Still short. I finally settled on a Magpul ACS-L (you could also use the regular ACS, which is the same length, but I wanted to save at least some weight) with the Magpul 0.70" extended buttpad.

My rifle, from the end of the bare buffer tube to the muzzle of the barrel, is 23 and 10/16" long.

Here are the measurements I came up with.

The BCM Gunfighter stock is 6 3/4" long.
With this stock, my rifle would be approx. 27 1/4" long. Too short.

The VLTOR eMod is 7 3/4" long.
With this stock, my rifle would be approx. 28 1/2" long. Too short.

The Magpul ACS-L with the 0.70" extended buttpad is 8 1/4" long.
With this stock and buttpad, my rifle is exactly 29" long.

Again, all of this was done with me measuring my rifle. Don't assume yours will be the same - measure it properly, and don't break the law.

Leper Messiah · Jul 19, 2016

So has anybody actually built a 9mm ar using a 8.5" barrel and got to 29" oal using the paired parts above? It seems like the actual length of a 9mm barrel is still in question.

Hawkeye · Jul 20, 2016

I have not done a 9mm one, but I did build the rifle that I mentioned in post #48, and it's exactly 29" long.

I think that they key measurement is the barrel length, because all of the other ones are going to be more or less fixed. (i.e. all uppers are going to be the same length, all lowers using the same buffer tube should be the same length, etc.) Thus, if I wanted to check measurements, the very first thing I would do would be to assemble the barrel on to an upper, put in a bolt, and take a barrel length measurement the ATF way (close the bolt, drop a rod down the barrel until it hits the bolt face, and then measure to the muzzle with no non-permanent muzzle devices). Then you should be able to use my measurements above to judge the rest of it. The one caveat is that since a 9mm is blowback, I don't know how using an A5 tube and buffer assembly is going to change the whole thing, and the A5 tube is critical because it adds about 3/4" of length.

j_h_smith · Jul 20, 2016

Okay you NFA gurus, I have a weird question about the 29" ruling. Lets say I make a SBR using a 14" barreled upper. So that I'm well beyond the 29" ruling. I get my stamp and I'm good to go.

Now lets say after I receive my stamp, I buy a 4" barreled upper. The law states that I can use other uppers without requiring another stamp.

Can I install the 4" barreled upper on my legal SBR lower and not be breaking any NFA or Maryland laws/rules/whatever?

I have met the requirement of both the state of Maryland and the NFA. Why can't I install this 4" barreled upper on my legal to own/stamp in hand SBR AR15?

Now it goes without saying that I must keep the 14" barreled upper, but why wouldn't this be a legal work around for the 29" ruling?

rbird7282 · Jul 20, 2016

j_h_smith said:
Okay you NFA gurus, I have a weird question about the 29" ruling. Lets say I make a SBR using a 14" barreled upper. So that I'm well beyond the 29" ruling. I get my stamp and I'm good to go.

Now lets say after I receive my stamp, I buy a 4" barreled upper. The law states that I can use other uppers without requiring another stamp.

Can I install the 4" barreled upper on my legal SBR lower and not be breaking any NFA or Maryland laws/rules/whatever?

I have met the requirement of both the state of Maryland and the NFA. Why can't I install this 4" barreled upper on my legal to own/stamp in hand SBR AR15?

Now it goes without saying that I must keep the 14" barreled upper, but why wouldn't this be a legal work around for the 29" ruling?

No, it's illegal. You may switch SBR uppers as long as you can return it to the original configuration. With any upper you still must meet the 29" or greater OAL. By using a 4" barreled upper you would be in violation of the minimum length requirement in MD. I'm doing an SBR and will have a .223 upper and a 300 blackout upper that way I only pay for one stamp.

Sent from my iPhone using Tapatalk

Hawkeye · Jul 20, 2016

j_h_smith said:
Okay you NFA gurus, I have a weird question about the 29" ruling. Lets say I make a SBR using a 14" barreled upper. So that I'm well beyond the 29" ruling. I get my stamp and I'm good to go.

Now lets say after I receive my stamp, I buy a 4" barreled upper. The law states that I can use other uppers without requiring another stamp.

Can I install the 4" barreled upper on my legal SBR lower and not be breaking any NFA or Maryland laws/rules/whatever?

I have met the requirement of both the state of Maryland and the NFA. Why can't I install this 4" barreled upper on my legal to own/stamp in hand SBR AR15?

Now it goes without saying that I must keep the 14" barreled upper, but why wouldn't this be a legal work around for the 29" ruling?

You can do that, but only outside of Maryland. If you do it inside of Maryland, you are guilty of possession of a banned copycat assault weapon (it breaks the "centerfire semi-automatic rifle shorter than 29" OAL" test from FSA 2013). If you have it here with the 14" barrel on it, and file a 5320.20 to take it to Virginia, you can cross in to Virginia and then put the shorter upper on it, since VA has no 29" law.

j_h_smith · Jul 20, 2016

rbird7282 said:
No, it's illegal. You may switch SBR uppers as long as you can return it to the original configuration. With any upper you still must meet the 29" or greater OAL. By using a 4" barreled upper you would be in violation of the minimum length requirement in MD. I'm doing an SBR and will have a .223 upper and a 300 blackout upper that way I only pay for one stamp.

Sent from my iPhone using Tapatalk

Are you sure about that? MD is the one that mandates the BATF to require the 29" measurement for the approval of the stamp. But does it say anywhere in the BATF regs that an additional upper must also meet these requirements?

Once you have your stamp (approved by MD law, well at least the interpretation of said law) Where does it state that additional uppers must meet the 29" requirement?

There is nothing in the MD law that addresses additional uppers. That's the Federal part of the equation.

j_h_smith · Jul 20, 2016

Hawkeye said:
You can do that, but only outside of Maryland. If you do it inside of Maryland, you are guilty of possession of a banned copycat assault weapon (it breaks the "centerfire semi-automatic rifle shorter than 29" OAL" test from FSA 2013). If you have it here with the 14" barrel on it, and file a 5320.20 to take it to Virginia, you can cross in to Virginia and then put the shorter upper on it, since VA has no 29" law.

But where does it say that in the MD regs? If I have the 14" upper with me and I install a 4" upper, where is this act defined as illegal in MD or Federal? I believe the MD law states that in order to receive your stamp, it must meet the 29" requirement. The Feds say I can change the upper. MD does not address this issue.

I still have in my possession the upper that meets the 29" law, but I am exercising my Federal right to change out to a shorter upper. But I still have the 14" upper with me at the time I install the 4" upper.

TheBulge · Jul 20, 2016

j_h_smith said:
Once you have your stamp (approved by MD law, well at least the interpretation of said law) Where does it state that additional uppers must meet the 29" requirement?

Right here...
(E) (1) “COPYCAT WEAPON” MEANS:

(III) A SEMIAUTOMATIC CENTERFIRE RIFLE THAT HAS AN OVERALL LENGTH OF LESS THAN 29 INCHES;

SBRs are all about configuration. The receiver is the firearm, but it is a rifle, pistol or SBR based on its current configuration.

A receiver is not a SBR even though it may be registered as one. Its only a SBR if it is configured as one.

BAFT doesn't care about OAL other than an identifying feature on the original form. A SBR is a SBR doesn't matter to them if its a 1" barrel or 15.5" Barrel its a SBR.

MD does care. A post ban rifle must be 29" or longer.
So in MD you can own/posses uppers that would make your registered receiver <29" but you can not configure them on a post ban receiver while in MD.

.

Hawkeye · Jul 20, 2016

j_h_smith said:
But where does it say that in the MD regs? If I have the 14" upper with me and I install a 4" upper, where is this act defined as illegal in MD or Federal? I believe the MD law states that in order to receive your stamp, it must meet the 29" requirement. The Feds say I can change the upper. MD does not address this issue.

I still have in my possession the upper that meets the 29" law, but I am exercising my Federal right to change out to a shorter upper. But I still have the 14" upper with me at the time I install the 4" upper.

Jim, I think the important thing here is to separate two things:
1) what you need to do in order to get the stamp
2) what FSA 2013 says about which rifles are legal and which ones aren't

You're totally right in that to get your stamp you need to meet the 29" requirement, and that after that you can modify the configuration of the rifle, however, those modifications must keep the rifle legal under both state and federal law. That italicized bit is important, because FSA 2013 says this:

4–303.
(a) Except as provided in subsection (b) of this section, a person may not:
(1) transport an assault [pistol] WEAPON into the State; or
(2) possess, sell, offer to sell, transfer, purchase, or receive an assault WEAPON.

Thus, mere possession of an assault weapon is illegal (unless you possessed it prior to 10/1/13 or met some other exemptions that we all know about).

An "assault weapon" is defined as:

4–301.
(D) “ASSAULT WEAPON” MEANS:
(1) AN ASSAULT LONG GUN;
(2) AN ASSAULT PISTOL; OR
(3) A COPYCAT WEAPON.

(E) (1) “COPYCAT WEAPON” MEANS:
(I) A SEMIAUTOMATIC CENTERFIRE RIFLE THAT CAN ACCEPT A DETACHABLE MAGAZINE AND HAS ANY TWO OF THE FOLLOWING:
(1)A FOLDING STOCK;
(2)A GRENADE LAUNCHER OR FLARE LAUNCHER;
(3)A FLASH SUPPRESSOR;
(II)(II) A SEMIAUTOMATIC CENTERFIRE RIFLE THAT HAS A FIXED MAGAZINE WITH THE CAPACITY TO ACCEPT MORE THAN 10 ROUNDS;
(III) A SEMIAUTOMATIC CENTERFIRE RIFLE THAT HAS AN OVERALL LENGTH OF LESS THAN 29 INCHES;

Thus, if you are in possession, in Maryland, of a centerfire semi-automatic rifle that is less than 29" in OAL that is not otherwise exempt (like you possessed it prior to 10/1/13, etc) you are in possession of an illegal "assault weapon" and are breaking the law. Thus, if you put a theoretical 4" barreled upper on an SBR that you didn't possess prior to 10/1/13 you have created an illegal assault weapon.

Now, you can legally transport that SBR out of state and put the 4" upper on it while you're out of state and that's perfectly legal. You just can't do it in Maryland.

Leper Messiah · Jul 20, 2016

I haven't purchased a barrel yet, I wanted to see if a 8.5" could get me to 29" before I bought one. If not, I'm probably going to get a 7.5" and keep it a pistol.

Hawkeye said:
I have not done a 9mm one, but I did build the rifle that I mentioned in post #48, and it's exactly 29" long.

I think that they key measurement is the barrel length, because all of the other ones are going to be more or less fixed. (i.e. all uppers are going to be the same length, all lowers using the same buffer tube should be the same length, etc.) Thus, if I wanted to check measurements, the very first thing I would do would be to assemble the barrel on to an upper, put in a bolt, and take a barrel length measurement the ATF way (close the bolt, drop a rod down the barrel until it hits the bolt face, and then measure to the muzzle with no non-permanent muzzle devices). Then you should be able to use my measurements above to judge the rest of it. The one caveat is that since a 9mm is blowback, I don't know how using an A5 tube and buffer assembly is going to change the whole thing, and the A5 tube is critical because it adds about 3/4" of length.

Squaregrouper · Jan 30, 2018

Thread revival...
I have measured and re-measured and conclude that by adding a ACS-L stock and the .70" butt pad, I will be >29" OAL with my PSA 8.5" .300AAC barreled upper. I won't need to use a different buffer tube. I am (theoretically) currently at 27.5" with a MOE stock and that barrel.
I'm gonna give it a try...

j_h_smith · Jan 31, 2018

squaregrouper said:
Thread revival...
I have measured and re-measured and conclude that by adding a ACS-L stock and the .70" butt pad, I will be >29" OAL with my PSA 8.5" .300AAC barreled upper. I won't need to use a different buffer tube. I am (theoretically) currently at 27.5" with a MOE stock and that barrel.
I'm gonna give it a try...

Are you measuring from the end of your barrel or the end of the muzzle brake/flash hider? I've got a 9mm 8.5" barrel and I can't get close to >29". I'm using the VLTOR EMOD with a 15" LOP and I'm still and inch too short. Your ACS-L has a 14.9 LOP. Add the .7 buttpad and it would seem you're still going to be almost a 1/2 inch too short.

Does PSA make a 9.5" barrel? I have a 300blk upper that has a 9.5" barrel. It's not a PSA, but if you do have a 9.5" barrel, you should be fine.

Good luck either way.

Discussion of how to get an 8.5" Barrel SBR AR15 to 29" OAL

The #1 community for Gun Owners of the Northeast

Member Benefits:

Active Member

Ultimate Member

Active Member

Attachments

Ultimate Member

Active Member

Durka ninja

The Leatherstocking

The Leatherstocking

Active Member

The Leatherstocking

Ultimate Member

Ultimate Member

The Leatherstocking

Ultimate Member

Ultimate Member

Active Member

The Leatherstocking

Active Member

Kragaphile

Ultimate Member

Users who are viewing this thread

Log in

Forum statistics