I was finally able to get to the range to try out my new PSA 8.5 in. 300 blackout AR pistol, and I was able to shoot both super and subsonic 300AAC with my Hybrid 46 Suppressor. Everything was perfect with shooting the subsonic ammo: 40 rounds with no issues whatsoever.
I also didn’t have any malfunctions with the supers, but they were extremely gassy. After 5 rounds my eyes were burning, it smelled like crap, and I had black spots on my arms after shooting, lol. Does this mean it’s overgassed for supers? Would an adjustable gas block fix this?
My setup is a PSA 8.5 in. 300 blackout upper, PSA AR15 lower. The only thing I changed was I swapped out the buffer for an H2 buffer. I am using Lancer 300 BO mags and a Silencerco Hybrid 46 suppressor.
Any help or advice would be greatly appreciated. Thanks in advance.
Thanks for responding. I am curious regarding your position on this. Suppressors are used a lot on supersonic rounds that are not inherently subsonic: 5.56 and 308 come to mind. Wouldn’t it be no different than shooting supersonic in those calibers? I realize that you will not bring the decibels down to subsonic levels but I would think you would still receive a fair amount of noise reduction.
The suppressor traps gas and keeps a higher “port” pressure when used. Normally subsonic loads burn less propellant and a somewhat faster propellant than supersonic loads. This gives a lot less gas at the muzzle for the suppressor to deal with.
It will reduce the muzzle blast with supersonic loads but do nothing with the sharp “crack” of the bullets sonic boom.
It’s not really a position, 300 BO was conceived and developed as a .30 cal subsonic round to be suppressed for covert military operations that gave them more lethality and options
I don’t know where 300 BO supers came along or why, and like I said while you can shoot it suppressed, you immediately found the drawbacks
As to 5.56 or .308 shot suppressed, my guess is that your results would be about the same as far as over gassing goes with 300 BO, with your particular suppressor
Suppressor design probably plays a larger part in all this than people think. Flow through designs such as Huxwrx would probably shoot supers better. If you already have a flow through suppressor, imagine how bad the overgassing would be if you didn’t
if you are interested i will go find the data for my 300 subsonic load.
i know it is a 168 gr bullet and it will cycle my full auto. i just dont remember the powder and charge.
there is a video on my u tube firing about 10 rds from the hip. they are real quiet. Davidautofull@aol.com
if i was a computer wizz i would have just placed the vid here.
and its a PSA 8.5 inch upper and YHM Phantom suppressor.
What surprised me was there was minimal gas blowback with the subs, but massive gas with the supers, which is why I was thinking that maybe an adjustable gas block to scale back when shooting supers might do the trick.
Thanks, I appreciate the advice. I am leaning toward the SA as well. Do you know if it would be considered low profile? The 8.5 in. PSA upper I have states .750" diameter low profile gas block in the description, and when I look at the fit to the handguard, it’s a really tight fit - there is zero excess clearance beyond what is already installed.
Hey, as a fairly newer subsonic shooter I’ve been digging around and looking for the best adjustable gas block to minimize gas back in my face. I found www riflespeed com for a toolless adjustable gas block. You have to have a little room between handguard and the threads of your barrel to have room for the adjusting collar. But their system is great. No more lost hex wrench or left it at home. Adjust in a second and on the run! Oh yeah, you need to run a straight gas tube. They sell them and so does Brownells. But your original gas tube won’t work.
Since this photo I’ve switched to a .5" shorter handguard. Just makes it easier to adjust! But I test it out and have my numbers for suppressed and unsuppressed shooting. The websitehas a calculator for determining barrel/handguard length so you get the right length gs block or if your current configuration won’t work.
Actually, I went to the range today and ran the suppressor on my 308 AR10 and my 7.62x39 AR15 - supersonic loads, of course, and I didn’t have nearly the issues I had with the 300 blackout supers. Gassing was minimal and no black crap whatsoever on my arms. It was a pleasure to shoot. I think I just need an adjustable gas block to tame down the gas when shooting supers suppressed on the 300 BO pistol, and hopefully that will resolve the issue.
Hi, thanks for sharing. I was looking at the Rifle Speed as well. Did you install it yourself? If so, was it easy to do? What upper is that, a PSA 300 BO upper? What barrel length? Mine is the PSA 8.5 in. 300 blackout pistol upper, and I was wondering how the fit was with the Rifle Speed since the room under my handguard is very tight.
Hey, yes I intalled it myself and it is very easy. (But I build ARs and have an armors toolbox set up)
It uses 2 set screws or can be pined depending on how you want to secure it.
I have 2 of these gas blocks. One is ons a 10.3 w/ 8inch handguard.
The other is a tighter. It’s an 8.5 inch barrel and a 7inch handguard.
