[Unclenick]

No question that the undersized bullet is worse for accuracy than an oversize one. The reason is that the loose bullet seldom centers in the bore so it is not often evenly engraved by rifling all around. This unbalances it so that it spins eccentrically, or wobbles in flight. Worst case they can actually fail to stabilize properly and tumble.

WWWJD, If you have a floating firing pin model, I would use either CCI #34 or TulAmmo KVB762 primers if you can find them. Both conform to the less sensitive military H-test spec. The TulAmmo, in particular, seat hard, but are good, consistent performing primers. With either one you want to check every single round to be sure they are seated below flush with the case head with a floating firing pin.

If you have a spring return firing pin model, then I'd go with any primer except Federal and Winchester, the former tending to be a little softer and more sensitive that some other makes, and the latter having been so some years and not others.