I personaly think that the 22-250 Ai is about the maximum effeciency size for the 22 bore , and its likely a bit overbore , after that it takes more and more powder to get smaller and smaller velocity increases. I have heard of some guys shooting 22-243's with 8gr bullets to 3700fps but it was with SMK's , I doubt that the Bergers or the A-max would handel that sort of stress , but Berger is supposed to start using thicker jackets and that would great help.
Heck with the speed and acuracy of the 6x47 Lapua I think I would just stick with that , if your dad has a problem with that recoil just add a couple pounds to the stock and a Sims recoil pad. The 105 A-max or 95gr Berger ought to be able to get pushed to 3300fps out of that case and with the added BC would be a step over the 22 cals all with added barrel life , heck even the 87gr V-max should get you to 1000yds on some praire dogs.
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