Mixed headstamp loading??

[charlie b]

The thing is, if you are willing to measure volume, (and I am), and sort for loading based on that, then it doesn't matter that they're mixed headstamps. At least as regards pressure, although admittedly quite likely losing some accuracy via using the mixed headstamp brass.

Ok, let's simplify this. Let's just take the "mixed headstamp" part out of the semantics of the question. If you are loading near max, and wish to volume check and sort your brass, what parameters should one use??

Vettepilot

It depends. (I always love that answer )

For things like benchrest competition it really doesn't matter what the case volume is, as long as all the cases are the same. 'We' have had discussions over the best ways to measure volume but the easiest is to weigh the cases. Do a full length resize or fireformed (pick one, another long discussion) and trim to same length. Weigh as close as you want. Pick 10 cases that weigh the same and use those for competing/groups. You can also use a fine substance, like sand, to fill the cases and weigh that. Some have used water, but, that is 1) messy and 2) not as accurate (IMHO).

For max loads it is more difficult. If you are not measuring the pressure you really don't know. Determining over pressure by stiff extraction, flattened primers, etc is a crap shoot. Note that you can be pretty far over pressure before seeing signs of it. I just use same headstamp but I am also a little below book max.

Short story. A customer (not mine, gunsmith was a friend) brought in a Dan Wesson in .357 cause it wasn't shooting well anymore. Test fire confirmed bullets were keyholing. Looking closer the factory rounds were 'loose' in the chamber, as it rattling around. Customer admitted to shooting reloads and had cases. Primers were not flattened out. Cases were not stiff to extract. When asked the customer said the load was Bullseye. When asked how much he said he just filled the case to not leave an air gap. He was lucky.

[charlie b]

PS even when weighing cases it does not guarantee the same volume, especially if you use different headstamp brass. The amount of brass in the rim area may be a bit different and affect the conversion between volume and weight. It may not be much, but, if you are weighing within 0.1gn then it may make a difference.

[Vettepilot]

PS even when weighing cases it does not guarantee the same volume, especially if you use different headstamp brass. The amount of brass in the rim area may be a bit different and affect the conversion between volume and weight. It may not be much, but, if you are weighing within 0.1gn then it may make a difference.

Yes, I know. That's why I specifically mentioned that I would "volume" sort these. It's a bit of a pain, but I don't mind, and as you say, case weight does not tell the story.

I just don't know how else to word my question!? When VOLUME, (not weight) sorting, what parameters to use?? How many cc's, or grains of water deviation is acceptable?? Plus or minus exactly how much variation in volume?

Vettepilot

[Krag 1901]

Yes, I know. That's why I specifically mentioned that I would "volume" sort these. It's a bit of a pain, but I don't mind, and as you say, case weight does not tell the story.

I just don't know how else to word my question!? When VOLUME, (not weight) sorting, what parameters to use?? How many cc's, or grains of water deviation is acceptable?? Plus or minus exactly how much variation in volume?

Vettepilot

Take the average and the upper/lower weights, in water grains/grams and look at the percentage of variation then sort by least variable weight in water to top of case. That should give you the volume (1 gram=1CC of H2O).

Or you could just buy some Hornady or Starline Brass and start with matching head stamps?

[charlie b]

How much variation is up to you.

I weight sort so I sort them in 0.1gn groups. Then based on the distribution of weights will choose a spread that fits my use. It will look kinda like a lopsided bell curve.

For volume (weight of water, sand, etc?) I'd probably do the same thing.

[bluejay75]

In my experience the more space that’s left in the case after you charge it the less it matters. As that space becomes less and less the more the variances in capacity will be magnified.