How is .30 Sherman mag with .300 prc loads?

[FimRire RongLifle]

I understand not something to do in a match but for fireforming how do they shoot with prc carts? I need to get on a build for a 30 light soon for someone and it's between norma/prc/Sherman right now however im trying to weigh the ff part as complexity or if they can practice with prc loads then load to Sherman mag after. Or am I overthinking and the brass is available to skip this?

 

[Tactical Taz]

I built a hunting rifle with a 30 Sherman mag chamber and have been shooting factory hornady 300 prc in it. My 1 example shoots about 3/4" where it shoots in two ragged hole groups. I suspect it is due to the stock needing to be properly bedded and would shoot about 1/2" or better. But it is plenty accurate for dropping elk currently. Only potential negative is the speed is slow. Not sure how much of that is due to the barrel or the fireforming.

 

[Taylorbok]

250 A-Tips on top of 81 grains of N570. If you can get ahold of 245 bergers you can shoot them a bit faster