The question related to 200 gr or heavier for subsonic loads? They should operate the action of an AR-15 pistol W/ 7.5 inch barrel. Thanks and Be Well, RZ.

4198....

but do you have access to 1680, 2400, or some of the CFE Blk?

Friend in New Hampshire ( not on the campfire) shoots one in an AR platform using 210 grain Cast bullets..

1680 is his favorite, followed by 2400....

I can get the Hodgdon powders easier than any others. RZ.

What about 4227?

While not a favorite of most. I have had excellent results with h110 and 220s. Accurate, cycles perfectly and I get last round bolt hold open with an 8.5 inch.

H110 is something I have some of. If it works I can get some more, maybe. Be Well, RZ.

tried trail boss. wouldn't cycle.

My favorite year of Corvette, a 67 uses a " 4227 " Tri Power.....

It will in a bolt action....

Trail Boss will work the best in a bolt gun......you need 1680 to cycle in a AR-15.....add a adjustable gas block if needed......

I've had success with both H110 as well as H4198 in 300 BLK cycling both supers and subs. They're both perfectly viable. If you're reloading en masse, H110 is messier but throws more consistently. H4198 is less messy, but it's a stick powder, so you tend to see a little more variance, at lease out of an Auto-Drum.

CFE Blackout? or maybe 231 so it functions with enough gas. It still has to be subsonic for the suppressor. Will at some point try to get a 308 suppressor rated for full auto just so it is built HD. Right now I will use what I have. And be stealthier at the same time. I have to go out to shoot the ACP first. Thanks for all the ideas. Maybe someone else will chime in with some real experience. I always learn from these answers. Be Well, RZ.

I meant to say H110/296. That would be for enough gas pressure. Thanks again guys. Be Well, RZ.