What effect, if any, will cartridge cases of slightly different weight (same calibre & make)have on reloading/accuracy/consistency?

Exactly the same effect as a varying powder charge, different pressure and velocity. It makes the load less consistent and can affect precision quite a bit if your barrel/load is sensitive to velocity/pressure variations. If the load is good, if the barrel time and vibrations are right, it takes extreme variations to see any effect at all. I would not worry to much about it unless you are after 1/2 moa groups, or better. If the case weights vary a lot the cases probably will be inconsistent in regards to wall thickness wich can give varying bullet pull, this is in my opinion a more serious effect, it affects the load more, so I stay away from case lots with wildly varying case weights. For a short belted magnum I want +- 2 grains consistency (1% standard deviation), wich is easy to find really.

Tron

In the world of practical reality, absolutely no effect.

Case capacity is more critical than case weight.

And, unless you are shooting a 0.25-MOA firearm, you are wasting your time checking either variation.

ricciardelli,

I need some help. Doesn't case capacity and case weight translate into the same thing? If two cases have identical external dimensions but different weights won't the internal dimensions be different.

[ 04-02-2003, 21:16: Message edited by: Mike M ]

Depends on what you mean by "slightly". Some folks use .5% of the average case weight as the yardstick for sorting.

Re: "Doesn't case capacity and case weight translate into the same thing?" Not necessarily. If the head in one is thicker, or there are differences in the extractor groove depth of the two, the internal dimensions could be vastly different. The easiest and best method of "uniforming" the cases is to fill them with water and weigh them. That will be the most accurate way of determining internal volume which is truly in what you are interested.

I recently bought 20 Lazzeroni Warbird cases. Their uniformity was a joke. Of the closest 19 cases out of those, the weight variance was 7g. They weighed �3.5g of 223g except for one which was way, way off. When I started sorting by water weight, the volume was suprisingly uniform. Don't recall exactly but they were all within about .7g of water and they shot surpising well.

[ 04-03-2003, 00:37: Message edited by: Bob338 ]