I just got some Hard cast bullets that I ordered. I ordered 370 Gr. The bullets that I got where 355 gr. I called and they said that the molds were 370 gr. That its depends on the mix of metel that gives final weight! My concern is, what data to use .They say 370 data. Most bullets I have used ,weight what the box say's. Shouldn't they mark them 355.gr???????What load data should I use 355 or 370 ???????? Jeff

Use 370gr. data. Molds re cut to produce a given weight bullet using whatever alloy that mold maker thinks of as 'standard'. Harder alloys will weigh less, softer alloy will weigh more, but the shape, seating depth, and bearing area of the bullet doesn't change.

Thanks, I'm new to cast bullets. Iv'e loaded jacketed bullets forever . So this is new to me. Jeff . Just want to be shure and safe!

The critical part of loading cast bullets, in my opinion, is the amount of case volume that the bullet occupies. So the bullet design,not the weight, would be the factor I look at as most important. If you work up from starting loads, you shouldn't have any problems.

I have got a few different brands of bullets and they vary from 2 to 15 grs depend on the Maker. I'm talking about batches. Its the 355 gr thats marked 370. that had me thinking! I'm a safety "NUT" when it comes to loading . I'm learning though, Thanks Jeff

As a rule of (the remaining) thumb you're safe using a lighter bullet (within 10% or so) in place of a heavier bullet. Pressure will decrease and velocity will be a bit higher than with the heavier bullet.
cukrus