pbcaster45, if that 3-shot group's .388 center-to-center, what's the unit of measurement?
.388 inch? The holes are too tiny for that to be the result with 28 caliber bullets.
.388 MOA? Then it's about right.
If that rifle always shoots 3-shot groups with that load no worse than that, then it's a .338 MOA rifle. If not, then it's a bigger on in MOA's one can count on. There's only about a 20% confidence of repeatability size wise for a 3 shot group. Claiming rifle accuracy based on a single 3-shot group's not gonna win very many bets. But that one's in the size range of being very good.
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