The variation you're seeing in electro plated bullets...especially in Rainier is common / in fact I would expect a bigger variation in weight in Rainier's bullets...( in 147 gr....maybe 3 or 4 gains of variation )...in weight than you've been finding ....and some variation in shape is common. But they're probably just fine for range practice.
Berry's plated bullets are thicker ...and I think you'll see less variation in them / or at least I've seen less variation when I've used them vs Rainier bullets.
Your best tolerances / most consistent weights, in my experience, will be seen in true jacketed bullets...like Montana Gold.
But all of these bullet mfg's mass produce their product....and we're not talking about "airplane parts" ....or "artificial heart parts" ....where tolerances are much tighter...bullets are an expendable product.../ while all mfg's do the best they can ....you're always going to find some variation in a case of bullets...regardless of what grain or style bullet you select.