It may be as simple as changing rifles. Gunpowder (yes, the same brand and type) changes between lots. Sometimes a little, sometimes more. Bullet makers change the material and inner design of their bullets.
That's why all the books say "This load may be over maximum in your weapon. Work up to maximum." Could be your firearm's "max" is greater than theirs, but it would real dumb to assume that.
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Archie
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