Subsonic Ammo

[419]

I am planning to purchase a suppressor in the next few weeks, and I have a question about ammo. In an 8 inch barrel, what is the lightest bullet weight that is consistently subsonic in factory loads? I plan to begin reloading, so maybe powder will be more available in the next few months while I wait on my ATF forms, but I just wanted to get a ball park estimate on which weights are subsonic, so I could begin making some purchases.

Thanks

[g22rmr]

175 is the lightest I've gone. Works great as long as you've got pistol length gas.

[plant.one]

in factory ammo i think you're going to be stuck with rem UMC 220's and hornady 208's. at least from major brand manufacturers.

some of the boutique manufacturers may have other subsonic offerings available as well, but i'm not familiar with them.

[BlogSarge]

I have a few boxes of Gemtech 187 gr loads on the way. Hopefully they will work well since they seem to be readily available and less-unreasonably priced than other stuff right now.

Stay tuned for results!

[419]

Thank y'all. I was hoping to hear that all of those ~147 grain bullets would be subsonic in an 8 inch barrel, to use for plinking, but I kind of knew that that would not happen.

[RDA]

You could have a 90 grain XTP loaded subsonically in a bolt gun (or hand cycling an AR). You don't mention what type of gun but with an 8" barrel or gas system, I would imagine it is an AR15. People have gotten 168 to reliably cycle a pistol gas AR15 with the right powder and properly built gun.

[419]

Sorry, it is an ar-15 with a pistol gas system.

[Dolomite_Supafly]

It depends on the size of the gas port. You can run a .120" port and probably run <150's at subsonic velocities.

I had a 16" barrel with a pistol length gas system. With a port that was drilled at .093 I was able to get 155's to cycle at subsonic velocities. They were barely subsonic but subsonic none the less. I ran a 3 way gas block where the subsonic setting used the .093" port and the supersonic setting was much smaller.

You could even go with a light wright BCG, lightweight spring, lightweight buffer and lightweight hammer spring. Adding those, with a HUGE gas port at the pistol position, you could probably get <130's to reliable cycle at subsonic velocities.

But the lighter you are able to cycle at subsonic velocities the more over gassed your gun becomes with supersonic loads.

[419]

I did not realize that the size of your gas port made that big of a difference in velocities. That makes me want to build a new upper to experiment with, or at least a new barrel.

[rjacobs]

I did not realize that the size of your gas port made that big of a difference in velocities. That makes me want to build a new upper to experiment with, or at least a new barrel.

has nothing to do with velocity, all to do with cycling. A big gas port will direct more gas to the BCG and allow it to cycle with lighter weight bullets. The trade off with this is if you shoot supers, you will be putting WAY WAY WAY to much gas to the BCG and the gun will beat itself to death hence why guys are saying to use an adjustable gas block to turn down the gas for supers.