With the appropriate can these would likely cycle your various AK/x39mm variants, but they are closing to going supersonic. Accuracy was very good at 25 yards, but it looked like the bullets weren't soo stabilize at 100 yds with the weird marks on the paper.  I tested them in gel, and the penetration was insane; 48"+, but very little expansion.  I think a copper expander would serve this role better, and if you want to shoot subsonic for the heck of it, Callaway's 220gr TMJ works better. I wish Brown Bear was still around!

These came from SG Ammo: https://www.sgammo.com/product/hornady-ammo-sale/20-round-box-762x39-hornady-255-grain-sub-x-subsonic-ammo-80787



7.62x39mm, 255gr Sub-X, Subsonic Hornady by Buffman RANGE, on Flickr

7.62x39mm, 255gr Sub-X, Subsonic Hornady by Buffman RANGE, on Flickr

Wow. I'm glad the things didn't tumble and ruin the suppressor.

Do they show a recommended twist on the package?

Also glad you were able to find one of those after they penciled through your get blocks.

I'll have to check. Nothing is on their website.