Suppressors Suppressed 9mm SBR Question

[SABuzzard]

Just got my tax stamps and was able to get my dedicated 9mm AR 15 up an running. 7" barrel with an AAC Tirant 9.

First trip out to shoot I tried American Eagle 147 gr and Speer Lawman 147 gr. My initial impression was wow this is still loud. It was significantly quieter than a Glock 4" firing the same ammo without the suppressor, but nowhere near as quiet as my 308 with subs through my Thundertrap. I realize it's a gas gun and will never be as quiet as a bolt gun, but it still seemed rather loud.

I backed down the firing line on the side opposite the action about 50 yards while a friend fired. It sounded almost like the rounds were going supersonic. I didn't have any 115 gr to compare it to.

So do you think 147 gr bullets could be going super sonic in. 7" barrel? How can I tell without a chrony?

Can anybody with first hand experience with a suppressed 9mm SBR give a better understanding as to hat I should expect?

Thanks

 

[50APIT]

Re: Suppressed 9mm SBR Question

I say it is possible that they are going transonic, maybe supersonic based on the below link:
http://www.ballisticsbytheinch.com/9luger.html

I don't know how hot either the AE or Lawman ammo is loaded as compared to the hydro-shock ammo tested at that link but it should give ball park estimate at around 1050fps.

A fairly simple way to see if the noise is from the sonic boom would be to shoot some 115gr or 124gr ammo you know is supersonic and see what sound difference there is.

On my 9mm sbr (5.5" barrel) there is a very noticable difference between supersonic and subsonic loadings if you are standing 10ft away or so. As the shooter, the blowback action is very load, but there is still a noticable difference between super and subsonic.

 

[SABuzzard]

Re: Suppressed 9mm SBR Question

Good Info - thanks for the link.

I'll try the 115s

 

[mavrick10_2000]

Re: Suppressed 9mm SBR Question

You may also be hearing the port noise from the blowback system and bolt. They aren't quiet like the H&K system on an MP5 which delays the bolt unlocking more than the AR blow back system.

 

[rbdub474]

Re: Suppressed 9mm SBR Question

The quietest factory ammo I have used in my 5" 9mm AR is the Fiocchi 158gr. subsonics. They are alot quieter than any of the 147gr stuff I have found.

 

[az_paul]

Re: Suppressed 9mm SBR Question

I agree with rbdub474 about the Fiocchi 158 gr. subsonics. I'm basing my comments on what I have run through the full-sized UZI and Gemtech Suppressor.

 

[SABuzzard]

Re: Suppressed 9mm SBR Question

I'll try the fiocchi 158s. Didn't know you could get a 158 grain with out reloading. Thanks!

Anybody try PVRI 158s? Found them while searching for the Fiocchi's.

 

[317millhand]

Re: Suppressed 9mm SBR Question

Im shooting the american eagle 147 in my handguns and it is quiet with the 45 tirant. Same ammo in my buddies beretta storm carbine is super quiet with his tirant 9. Have you tries shooting it wet? The wire pulling gel works greaat

 

[BravoSector1]

Re: Suppressed 9mm SBR Question

I'm shooting the AE 147s out of a 6.5" 9mm barrel for a Glock 24 and they are a hair away (chrono) from being supersonic. The 147s are always supersonic out of my 16" 9mm AR. The 158s do work well.

 

[blksno]

Re: Suppressed 9mm SBR Question

I've sent 9mm 147 hand loads through a 16" barrel with a can and they were OBVIOUSLY subsonic. No doubt about it.
In fact...got a video of it somewhere...but alas, try that 158 stuff if you're not reloading. Or snag a box of other kinds of 147 and see what sounds the best.

 

[762frmafr]

Re: Suppressed 9mm SBR Question

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2509697#Post2509697

5" barrel and a YHM WraithXL