9mm AR15 Suppressed

[giggitygiggity]

OK. I want an AR15 in 9mm. I want it to be sound suppressed. What are my options? I am not sure what all is out there as far as integral suppressors or if it's just easiest to do a SBR with suppressor. What is available and what is quietest? Thank you.

 

[brobin10]

well for starters i think integral suppressor may on be one tax stamp where SBR and silencer will be 2 tax stamps

im going with SBR and suppressor. DDLES dedicated 9mm lower bc i like the look of it way better than the normal ar15 lowers however a regular ar15 lower will give you more options in the future...

 

[The King of Pants]

Integral will only be 1 stamp if your total suppressed barrel length is over 16 inches. Otherwise you'll still need to register your lower as a SBR.

 

[Prince Yamato]

It's a price difference of $200 (for two tax stamps vs one).

 

[jmorris]

I built the one I have, without the end cap it is 16 1/8" long to keep it legal with one stamp. It makes less noise than an evo 9 on a 16" barrel.

 

[jmorris]

A little more food for thought, living in TX, I could take the above rifle to AR this weekend or even LA. If you SBR you have to notify the ATF to cross State lines ( ATF Form 5320.20 ) and some like LA allow suppressors but no SBR's.

 

[zeb777]

I have a questing on this topic...

If you permanently attach the suppressor to the weapon like a long flash suppressor, could you get away with having only 1 tax stamp?? (The stamp being for the suppressor not the SBR)

example: 14.5in barrel with a permanently attached 4inch suppressor, making a total of 18.5 inches?

I know it works with mussel brakes and flash suppressors, would that work?

 

[hq]

It probably will, if it's permanently attached. However, I'd suggest a shorter barrel and a much larger suppressor - the volume and muzzle pressure of gas call for a larger can if you want it to be "Hollywood-quiet" with subsonic ammo. My ~11" (I honestly can't remember if it's 10½ or 11") 9mm AR has a fairly loud report with a small 4" x 2½"dia BR reflex can, while a 10" x 2" dia Vaime can kills the muzzle blast completely.

 

[MasterSergeantA]

I have a questing on this topic...

If you permanently attach the suppressor to the weapon like a long flash suppressor, could you get away with having only 1 tax stamp?? (The stamp being for the suppressor not the SBR)

example: 14.5in barrel with a permanently attached 4inch suppressor, making a total of 18.5 inches?

I know it works with mussel brakes and flash suppressors, would that work?

It should work just fine, zeb. But at the risk of being accused of 'over-thinking' the answer, I would offer the following steps:

1. Buy or 'make' the suppressor on the appropriate Form 1 or 4 after getting the approval back.

2. Permanently mount the suppressor on the barrel...not the "rifle"...using the ATF approved method of permanent attachment. The barreled upper should be nowhere near the lower during this step.

3. After permanently mounting the suppressor so that the new barrel length is > 16", put the upper on the rifle lower.

If you had a lower, the suppressor and the upper with the barrel cut down all sitting on the workbench together, you 'could' be in violation of the NFA. Unless you already have visits by the ATF on a random basis, probably not an issue. But I tend to err on the side of caution.

 

[jmorris]

Post 7,8 and 9 yes that is exactly what I did. It is a short barrel with the "can" TIG welded to the barrel at 16.125" without endcap.

 

[xx7grant7x]

I tend to appreciate simplicity, as such went with the Olympic arms 9mm upper. No need to change buffers, uses sten mags (cheap), and works. No sbr for me in Wa but have thought of the perm suppressor idea...

 

[hq]

There's one thing that favors the integral route: you can have a very large volume suppressor built around the barrel and have the barrel "vented", ie. have a competent gunsmith drill a number of small holes to the barrel itself, so that the gases expand to the first, very large expansion chamber that surrounds the barrel. The rest of the suppressor will be baffled, of course, where the bullet has left the barrel and is in free flight.

This design has two advantages:

1. Vent holes slow down the bullet, cheap std ammo will leave the barrel subsonic
2. Muzzle pressure is lower and gas expansion is distributed evenly throughout the suppressor

It'll be extremely quiet with most ammo and not having to buy fairly pricey Lapua/Magtech/etc. subsonics to keep it that way is a plus. My integrally suppressed 10/22 is built like that. The barrel looks much like an ordinary target/bull barrel, but it's in fact a very large volume 1" dia suppressor. On an 9mm AR you can fit a similar design under a free float handguard for a MP5SD-look.

 

[jmorris]

I personally would not go the ported barrel route. I reload 9mm 147's for IDPA and USPSA and they are subsonic to start with and I don't have to change setups to reload for every 9mm (except major 9 but that is a different story).

The one thing I have learned is that my loads run perfect in everything except the MP5SD because of the porting. Out of a standard MP5 they are fine.

Its not like you can't get enough volume under the freefloat tube anyway. Before you weld just make sure you have the barrel nut inplace.