Suppressors form 1 process, LMT as a SBR?

[corey4]

i am thinking about cutting down one of my ARs. when i hang my can off the end of it, it is huge.

what is the proper form 1 process? i know there is engraving of the name and city, and that is about it.

also, how much velocity will i lose going from 16" to 10.5"? also, why does everyone cut it 10.5"?

i have a trust set up that it will go on, if that matters.

 

[bengineer]

Re: form 1 process

Download the Form 1 from atf's website. Fill it out in duplicate and submit with the requisite forms: fingerprints (if not to a trust, etc), C of C, your check for transfer tax.

Check atf's site for engraving depth requirements.

If you cut a 16" barrel down, you will need to move the gas port and get a new gas tube. Easier route is to buy a pistol upper AFTER your Form 1 clears, or just a barrel w/ gas block & tube.

I have found 10-12" 223 works better than shorter. The shortest barrels have some issues cycling due to the shorter dwell time, and probably a host of other issues. Exactly why 10.5" is probably a neat history lesson.

Don't get bogged down in formalities or process. None of this stuff is that hard, you just need to know what you are doing before you do it, so as to stay legal. That is why we have gun attorneys and gun dealers - they (are supposed to) know what they are doing.

 

[al1gator]

Re: form 1 process

Tag

 

[corey4]

Re: form 1 process

what if i would decide to cut the barrel right after the FSB?

the orange line in the pic.

 

[Killswitch Engage]

Re: form 1 process

Why not just buy a barrel rather then cut and thread???

 

[corey4]

Re: form 1 process

i am just trying to make this as economical as possible.

 

[stik]

Re: form 1 process

I'm not sure but I think that you would run into problems cycling if you cut the barrel off that close to the gas hole. It would probably be cheaper to buy another barrel or sell/trade than to get that one running right after cutting it off.

 

[corey4]

Re: form 1 process

sooo....what's the difference in what i would like to do in relation to this:
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=328950199

i am not trying to be argumentative, but i must be missing something.

 

[stik]

Re: form 1 process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: corey4</div><div class="ubbcode-body">sooo....what's the difference in what i would like to do in relation to this:
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=328950199

i am not trying to be argumentative, but i must be missing something. </div></div>

Length of the gas system. I'm really not sure if a rifle length gas system would have enough back pressure to cycle the action reliably with the muzzle that close to the gas port. You may be able to open up the gas port to a size that would function reliably. It may take a few tries to get it to run. The short 10.5" barrels aren't particularly reliable either. YMMV

 

[stik]

Re: form 1 process

The 12.5" barrels seem to run pretty well.

https://danieldefense.com/cold-hammer-fo...ov-profile.html

 

[corey4]

Re: form 1 process

so the SBR uppers come tuned to run with a short barrel?

 

[stik]

Re: form 1 process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: corey4</div><div class="ubbcode-body">so the SBR uppers come tuned to run with a short barrel? </div></div>

Yeah they have a (hopefully) correctly sized gas port hole for however much barrel they have. This seems to be the case these days. A few years ago when short barrels weren't available from as many vendors you often had to match the gas port hole size yourself.

 

[corey4]

Re: form 1 process

gotcha. thanks!

is there a potential for running into problems when i slap on a can?

 

[stik]

Re: form 1 process

There shouldn't be any problems with running a can on it as long as the can is designed to work with a short barrel and most 5.56 cans are rated for 10.5 or so. Putting the can on it will change the amount of gas going into the action though. (There will be more)

It shouldn't be a problem though.

 

[corey4]

Re: form 1 process

running my yhm 30 cal can on my AR, i can tell there is a good bit of blow back. also, sometimes the bolt doesn't stay open after the last round.

 

[stik]

Re: form 1 process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: corey4</div><div class="ubbcode-body">running my yhm 30 cal can on my AR, i can tell there is a good bit of blow back. also, sometimes the bolt doesn't stay open after the last round. </div></div>

Yeah, I prefer to shoot bolt guns suppressed just because I hate getting a face full of gas when I shoot. I've shot a few rigs that were really bad. A 30 rounds mag dump with a suppressed 10.5" M-16 was enough to choke me pretty badly. I think that's when I decided a bolt gun might be more fun.

 

[bengineer]

Re: form 1 process

Corey4, to your question on the orange line pic:
Longer sight radius/front sight and gas block further out means more restriction in the gas tube (simple physics). Shorter barrel past said gas block means shorter dwell time and less resultant gas getting into the action. If this worked out perfectly, you would have less blast gas in your face. In reality, you will end up with a single shot or an unreliable gun.

Most manufacturers test and find the same results. This is why most companies make the same formats of barrel/gas block, barrel length after the gas port, etc. If you want a shortie and to have it reliable, buy a barrel or an upper. With the upper, at least you can count on some level of customer service as opposed to building it yourself.

And this doesn't even touch on gas port size, etc.

 

[corey4]

Re: form 1 process

thanks guys.

 

[corey4]

Re: form 1 process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: corey4</div><div class="ubbcode-body">sooo....what's the difference in what i would like to do in relation to this:
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=328950199

i am not trying to be argumentative, but i must be missing something. </div></div>

regarding the link in my post, are the LMT SBR uppers decent when run suppressed? i have a parts gun (M&P 15) that i can use the BCG on.

 

[johngfoster]

Re: form 1 process

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ben in WY</div><div class="ubbcode-body">If you cut a 16" barrel down, you will need to move the gas port and get a new gas tube. Easier route is to buy a pistol upper AFTER your Form 1 clears, or just a barrel w/ gas block & tube.
</div></div>

This is only true if you're going shorter than 10.3". Longer than that, and you can keep your carbine gas system and FSB. You will likely need to open up the gas port a bit. And to do this you'll have to temporarily remove the FSB to get at the gas port. LMT runs a 0.071" gas port, I believe, on their factory 10.5" barrels. They run like sewing machines.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: corey4</div><div class="ubbcode-body">
regarding the link in my post, are the LMT SBR uppers decent when run suppressed? i have a parts gun (M&P 15) that i can use the BCG on. </div></div>

I love mine. I'm running it with the KAC NT4 can and have not yet had any problems so far. Mine is a factory rifle, so it came from LMT @ 10.5" and all the work/tuning was already done. The only malfunction I've ever had was with a Surefire 60rd mag using Brown Bear ammo that sat in the freezing cold about 30 min. before I put it in the rifle. The mag follower wouldn't push the rounds up.

 

[Jacklulu]

Re: form 1 process

Nice rig
Wish I could have one
But will Truely have to buy a vacation home in a Free state before I can set my LMT up like that
john