Rainiers bullets are electro plated...and if you take a handful of them out of the box...and weigh each one...( in 230gr RN, I've seen variations as high as 5 grains ( on the low side )...not much on the high side ).....but I think that accounts for some of the flyers using Rainier bullets. You will see some variation in shape as well typically out of a box of their bullets.
Berry's plated ...have a much thicker plating / and most guys find them more consistent ....and shoot tighter groups with them.
FMJ ...like Montana Gold, etc...are just a better product / much better tolerance on weight / more consistent on shape.
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I think Rainier are fine for semi-auto's at moderate velocities...in calibers like 9mm or .45 acp / their bullets do not have a cannelure, so I would not trust them in a revolver...and never trust them at higher velocities in magnum loads especially ( I've seen them fracture and fragment in .44 mag ...maybe because they were crimped too tight with no cannelure --- or maybe because of velocity ...hard to tell ).