What is acceptable weight variation in brass

[lcarrico]

I've reloaded for 35 years. However, I've never really worried too much about "extreme accuracy". I've always just picked up a bunch of brass from the same lot and worked up a load for hunting.

My question is...I just picked up a bunch of 7-08 Remington brass and necked it down to .260 Remington. I then trimmed them and turned the necks a little to take off the high spots. Now that I've weighed them, I find that they weight from 161.4 to 165.5 grains. Is that acceptable? There is only 1 case that went above 165 grains. Should I just throw that one out or use it as a sighter?

RR


BTW -- I've been lurking & reading for awhile now. Great site. Lots of fantastic information here. Congrats to all who have made it so.

 

[ronemus]

I did an experiment several years ago to determine just how much effect brass weight has on .223 loads; I'd expect the effect to be smaller in larger cases. I used WW brass,sized, trimmed and deburred, primer pockets uniformed, flash holes deburred, and neck turned), WSR primers, charges of RL-15 or N-550 powder weighed to 0.1 gr, and 75 gr A-Max bullets. Using the lightest and heaviest cases,sorted from 1000 once-fired I had on hand), I had two lots of 10 cases with a 3 gr difference in weight. The average muzzle velocity difference was 16 fps, just a bit more than the 12 fps due to 0.1 gr of powder. I choose to sort 0.5 gr lots of brass for my long range loads, but the effect will only matter at 800-1000 yards - the vertical displacement on the target from such a small velocity change is negligible at shorter distances. Unless you control all other sources of variation, the effect of brass weight is negligible.

 

[tenring]

I weigh Lapua brass and sort it before trimming, sizing, etc. After all, you want to group together by weight, those cases with similar internal dimensions. Usually, with Lapua, a variance of 1.5 grs. is normal.

 

[Ackman]

People sort by weight assuming that more weight means less case volume. But measure case volume after they've been fired and trimmed to the same length, you'll find that's not true.

I weigh Lapua brass and sort it before trimming, sizing, etc. After all, you want to group together by weight, those cases with similar internal dimensions. Usually, with Lapua, a variance of 1.5 grs. is normal.

Sorting brass by weight before trimming is meaningless. However Lapua is very consistently the same length and trimming is unnecessary. But with any case, weight variation can be from anywhere.....the neck, the rim, the extractor groove.