Help me build an pistol/suppressor combo!

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Mauser lover

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Hello NFA experts! Or... experts in building NFA goodies! I need your help!

Here's the situation. I know pretty much nothing about any NFA goodies, other than what I've read about applying for the taxes. I think I have that covered. But right now, I am looking to build a CQB style thingamajig. I want something short, and something reasonably quiet. For now, I'm thinking .300 Blackout/AAC

My questions:

1. What barrel length? I want it to be reasonably short, after I put a silencer on the end. Which brings up my next question...
2. How long do suppressors run for a .300? I'm thinking I will want one that can handle a .30-06 as well, so experts, please take that into consideration.
3. I've heard that pistol buffers can have problems. But... I plan to start my journey with an AR pistol build, put a can on it to see if I like it before I get a stamp for an SBR (I have no experience with these, so I might not even want an SBR [or AR pistol for that matter] after all). Is it feasible to run a carbine length buffer tube on a pistol AR, or are there no real problems with pistol buffers?

So... let me know what I should do, state your arguments (civilly please), and help me build this thing! Absolutely everything is still in flux at this point, except I have a stripped lower already. Should I go with an integral suppressor and get 16.1 inches and just forget the SBR? Should I go with a 7.5 inch barrel right off the bat? I've been eyeballing PSA's pistol kits and drooling...

Please note, this build is particularly in consideration for combination with the suppressor. It might branch into an SBR build in the future, but I put this in the NFA forum because I want it specifically for use with the suppressor.
 
Ok, if you are planning on building a suppressor (form 4), plan the length of it to coincide with whatever short barrel you plan to mount it on at 16+". That way after you build the suppressor you can decide if you want to permanently mount it on the barrel for a one stamp build. I believe you can send a letter to the batfe for a length correction on your form 4 to whatever length the suppressor/barrel unit ends up at. Then you can throw it in an upper casting and throw it on a regular rifle lower. Otherwise just use a pistol lower for a one stamp build...
 
Sounds like you want to know:

1) What barrel length for a .300blk

When I was looking into it, no advantage was gained beyond 10" or so for subsonic, and little was gained beyond that for supers. I load my blk for full burn before 10" on subs and maximum accurate velocity from supers. I hunt VA white tail almost exclusively with 110 gr blk supers and a can on a ~10" pistol gas barrel. Works good. Subs and supers, can and no can, all cycle well. The 110's put em down just fine inside 100 yds, and subs are fun for plinking.

2) How big of a can for 300 blk?

If you want to get the full range of performance from 300 blk, plan on a .30 cal rifle can. Pistol cans generally can't handle the supers. Probably gonna be about 8" long. With the previously mentioned 10" barrel, that makes 18" ish inches, depending on mounting.

3) Can I use a carbine/rifle buffer tube on a "pistol"?

Yes. Don't have a combination of parts near by that could only be configured in an illegal way... don't have a stock without a 16" upper on hand too.

Lots of "braces" out there as well that work fine for plinking/blasting as well.

Technical notes:
Building your own can requires a Form 1, not Form 4.
 
Mauser lover said:
Is it feasible to run a carbine length buffer tube on a pistol AR, or are there no real problems with pistol buffers?
Click to expand...
The buffers and buffer springs are the exact same, and the internal dimensions of the tubes are the same. The only difference between a pistol buffer tube and a carbine buffer tube is the pistol one can’t accept a stock. This is to avoid any potential issues of illegal constructive possession of an SBR if you have a stock lying around.
 
Theohazard said:
The buffers and buffer springs are the exact same, and the internal dimensions of the tubes are the same. The only difference between a pistol buffer tube and a carbine buffer tube is the pistol one can’t accept a stock. This is to avoid any potential issues of illegal constructive possession of an SBR if you have a stock lying around.
Click to expand...


Oh! Thanks!

What's ya'll's experience on short barrel maneuverability? That's what I was asking concerning barrel length. If I've got 8" of can hanging off a 10 inch barrel, that isn't any better maneuverability than a standard carbine. If I put 8" of can on an 8" barrel, now I have a quiet carbine.

At this point, I seriously doubt I'll do a fixed suppressor.
 
For barrel length I would go with either a 8" if you plan to only shoot with the can on the gun, or a 10" if you plan to shoot unsuppressed occasionally. I have a 10" barrel on my SBR and think it's about the best compromise between short OAL when suppressed and reasonable room for my hand out front.

If you plan on always shooting suppressed, consider getting a hand guard that will fit over the can. Think 10" barrel, 8" suppressor, 15" handguard. This setup gives you lots of room for your hand upfront as well as mounting lights/slings, etc and protects your suppressor a bit. If you go this route, it is not recommended to shoot the gun without the suppressor attached.

If you want to shoot .30-06, you'll need a good .30 caliber suppressor. These will generally be quieter on a .300 Blk anyway, but you are looking at about 8" in length. I think Liberty has a suppressor for .300 Blk that is shorter (but larger diameter) which might work. I don't recall if it is rated for .30-06 but I would expect that it is.

You are correct that a 10" barrel plus 8" suppressor gives you about the same length as a 16" barreled AR with a flash hider. What you get by doing the .300 Blk/short barre/suppressor is a gun that is hearing safe and is not ballistically disadvantaged by having a short barrel (.300 Blk was designed for a short barrel while .223 gives up a lot of velocity between a 10" and 16" barrel).

And a last piece of advice, if you think you might want the SBR, just do it and get the paperwork started. Its not worth it to wait 5 months trying to decide, and THEN having another 6-8-12 month wait ontop of that. Trust me, if you want to do this type of build, you'll enjoy having it as an SBR.
 
I have an 8.3” barrel 300 BO upper for my SBR. Combined with my AAC SDN-6 it’s still well under 16”. The issue is weight. A heavy-duty .308 can is heavy and is way overbuilt for 300 BO, even with supers.

I want a lightweight QD .30 caliber can that’s a little shorter than my AAC, but still handles full-power rifle loads like 300 Win Mag and is still quiet. I’ve decided I’m getting the Q Trash Panda. It’s almost half the weight of my AAC. It’s not as heavy-duty, but I only plan to use it on my 300 BO and on a bolt action, so it should hold up just fine.

Q is a new company, it was started by Kevin Brittingham of AAC who left there and designed SIG silencers before starting this company. He’s one of the bigger names in the silencer industry and his designs are very good.
 
Last edited:
Theohazard said:
I have an 8.3” barrel 300 BO upper for my SBR. Combined with my AAC SDN-6 it’s still well under 16”. The issue is weight. A heavy-duty .308 can is heavy and is way overbuilt for 300 BO, even with supers.
Click to expand...

How much is "well under 16"? Are we talking .75 inch as "well under" or are we talking two or three inches?

The .30-06 would be a hunting thing, not thousands or even hundreds of rounds on the range like the Blackout. So, it doesn't have to be a perfect or extremely silent can for the .30-06, just able to stand the blast. Again, probably building it myself, so it will be overbuilt anyway.
 
Mauser lover said:
How much is "well under 16"? Are we talking .75 inch as "well under" or are we talking two or three inches?
Click to expand...
I don’t have it in front of me, but I seem to recall even with the can it’s about 2 inches shorter than a regular 16” AR with a flash hider.
 
If the op registers his sbr with an overall length based on a 10" barrel, but decides he wants to put something shorter, like a 6 or 8" barrel on it later, can he just do it, or would he need to notify the atf and fire some sort of addendum to his paperwork?
 
You can change the upper to another configuration (different barrel length, different caliber, etc.) all day long on an SBR; no questions asked, no permission needed, no need to tell the ATF.

However, if you no longer own the parts needed to put it back to the original configuration, the ATF asks that you notify them via letter of your SBR’s new permanent configuration (overall length, barrel length, caliber). But last time I checked, this was simple a request, not a requirement.

For example, my SBR is registered with a 10.5” 5.56 barrel. I swap out my 8.3” 300 Blackout upper all the time without any notification or permission needed. However, if I got rid of the 5.56 upper entirely and no longer owned a 10.5” 5.56 upper, it would be a good idea to notify the ATF of my SBR’s new configuration.
 
There’s an incredible build on here somewhere. Where a complete gun fit in a 30 cal ammo can. Upper, lower, suppressor, mags...just can’t remember who it was. I will look for the thread. It would be right up your alley but cheaper if you didn’t buy the spendy bits like folding buffer and removable barrel attachment. Your looking at about 26ish inches OAL.
 
Sounds like something MachIVshooter would build... I'd be interested in seeing it...

Anyone want to dissuade me from .300 BO? Pros/cons with a blowback 9mm? Other calibers?
 
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