I'd still be surprised, particularly at subsonic velocities. I definitely would not screw my suppressor on until I was darned sure they were stable.
Midway has the 190 Sub-X in stock ($46/100), I waited months for them to come back in stock before I was able to order any (last fall), then they ran out again and it took a couple of more months for them to come back in stock. They recently got them back in. If it's something you're set on I would order them now.
I even wonder about the 190 Sub-X at subsonic velocities... While my 300 Blackout (Rem/AAC Model 7) has been incredibly accurate with supersonic Speer 150 gold dot blackout bullets and Barnes Tac-Tx 110 bullets, I've never got more than what I consider middling accuracy with the subsonic heavies. Maybe I just need to find the right load yet???
Jerry
Good info, thanks! If a guy really had trouble with stability, the 170 SubX bullets for the 30-30 would certainly be an option.
