I'm not sure I wouldn't prefer the 10 gauge... 530gr is more than 3x the standard .308 bullet, takes alot to move that... Do you know what kind of velocity your load is getting?
No thanks. I've seen the cartridges before. Those doubles are a class act-Especially a Rigby or Holland and Holland.By the way: try a 470 Nitro Express some time. I have a Double Gun
in that caliber. One does not go to the gun range mearly to plink
at a target with that one. The Double was made by Rigby.