What sort of dispersion should one expect with reloaded API projectiles, either 622.5gr or 647gr, and Hornady AMAX?

I can't say on much on the groupings for APIs and APIT. I own a few of each, but being what they are, my local ranges wont let me shoot them for the potential fire hazards. Saving them for a rainy day....literally in a sense right? lol......But on the AMAXs, I can say at 100yds at my local range, my M95 does a little over an inch in groupings. I did find that the PMC's 740gr match does better in my M95 than Hornady's AMAXs, a little under a inch. I caveat all that with that I shot both the Hornady and PMC when I just bought it, like, I put a dozen of Milsurp M33s through it prior. Something odd I'll throw in about my M95, it likes the PPU 625gr ball ammo, did better than LC 660gr.

Thanks for the info. I thought this wasn't going to get a response.

I don’t know if this member frequents this portion of the forum, but you ought to reach out to “50Cal”. He used to work for Barrett and actually built the M95s. He’d be the go-to guy on anything Barrett, especially M95s. He should be able to tell you realistic accuracy on certain rounds.