How much weight deviation is acceptable for accuracy?

[JSnover]

I still don't see where the OP said what he was actually doing with these boolits. On the weight question, +/- .3 grains may not even be noticeable if the target is close enough.
The real problem is he started with crappy boolits and probably won't get any good data from them, just a bunch of shotgun groups and a trip back to the loading bench.
If I was handing out advice, I'd say to get some recommendations from other members about good quality commercial cast or ask to borrow some well-made boolits from somebody (Sorry, I don't have any cast in that size), then he can get down to some serious load development and accuracy testing.

[Tripplebeards]

I might have to start sorting in .5 gr and give it a try. I have been sorting In 1 grain increments on on my 44 mag, 450 BM, and 35 rems. I shot sub MOA the other day at a 100 yards with my 77/44 doing this and four other loads shot 1.25"- to 1.5". Maybe I can tighten things up a little.

[pls1911]

In my experience casting (35 years +), for anything less than bullseye shooting at rifle ranges, +/- >.5 grain is plenty close for well formed bullets.
Most of the time +/- 1 grain will be unnoticed.