I did a random weight check on my 40SW brass (assorted headstamps). It was cleaned and unprimed--just the brass. I checked the case length and they were all the same, but as much as 10.5 grains weight difference!!! Is that too much? I don't usually sort handgun brass, but should I?

I'm not as concerned about the lack of weight uniformity. I doubt there are many, if any, people who could tell the difference in accuracy with a hand-held firearm at normal pistol distances with the kinds of deviations I'm talking about here. I'm not talking about bench-rest accuracy.

My concern is not the presence of the weight/capacity deviation, but the amount of deviation-- well over 15%. I don't know how much a % of change in case capacity affects pressures, only that it most certainly does. All reputable manuals advise reloaders of semi- or full-auto firearms to make sure the ammunition does not allow for bullet setback for this very reason.

My concern is about the safety of the ammo, because the weight is a factor in determining case capacity, and therefore pressure, and therefore safety.

If you change your powder charge by that amount, you can very quickly go from safe to unsafe (or vice versa) pressures. It's also my understanding that, because of the nature of smokeless propellants, the pressure curve can rise exponentially rather than linearly at unsuitable pressure levels (high or low).

I do find cases from the same manufacturer and especially from the same lot to be more accurate than mixed headstamp brass but I have never weighed any. My auto handgun ammo doesn't need to shoot better than I can off-hand so I don't get anal about it. If I were shooting handgun competition (which I don't) I would probably sort for weight. Just depends on how accurate you can shoot whether it matters.

I dump all by pistol brass together by caliber and don't worry about maker for practice ammo.

When I load for serious hunting or self defense I like once fired by the same maker. But I don't worry about what one I use.

I shoot tens of thousands of rounds of practice ammo for every one round of serious ammo.