Don't forget that another solid option is Underwood. They also make 220gr hard cast lead at similar velocities.

This vid is a great reminder to test your carry ammo.

Soak the barrel. Those grooves are full of lead. That will increase chamber pressure A Lot Baby. (Austin Powers) Great video showing this in real time.

My stock G20 Gen 4 blew primers out of about 1/3 of the same rounds I tested, Buffalo Bore "HEAVY 10mm OUTDOORSMAN" 21C/20, 220gr Hard Cast FN, lot #13. Buffalo Bore has failed to respond to my emails. I know they work fine in some firearms but it doesn't take much searching to find plenty of people who have had problems with this load. I have decided that the failure of this ammo, and the failure of Buffalo Bore to respond, are big enough issues to not use Buffalo Bore ammo if your life depends on it. Best used for failure drills.

The Sig spring is really strong, I have had both Sig & Glock 10mm and the Sig spring was much heavier. But maybe the one you have might not be as strong. I am not sure. Keep us posted, please. Thank You

Try a heavier recoil spring on your pistol might help.. that brass is shooting way far from you.. your pistol is also taking a beating from those Heavy High Velocity rounds..

Brett Koski, any updates since you last shot? Have you tried any other ammunition like Underwood? How is the 220 running you?

Why do/did you need ammo that hot.?