LC brass sorting

[Hoodlum]

I spent the better part of 3 hrs tonight sorting out some LC brass I have resized in the past and had stored away... It ranges from LC74 to 69 to some 89's, and some with the nato cross on them.... Several have just a few of certain dates, and a few with the cross with the majority being 74... I proceeded to weigh the cases and sorted according to weight... 176.6-177.5, 177.6-178.5, 178.6-179.5, etc. You get the point. Anyways, the random stamps weighed within the boundaries of the 74 stamp. Should I keep the different stamps separate, or will they work in the same pressure range as the others of the same weight category?
Hoodlum

 

[rduckwor]

What are your plans for them?

Precision loading or plinking?

 

[Hoodlum]

What are your plans for them?

Precision loading or plinking?

Precision plinking!!!!! LOL.... I don't competition shoot, just paper here at the farm, but I like to get the smallest groups possible. My rifle can easily shoot .5 moa, and I try to do that at each shooting session....
Hoodlum

 

[WadeP]

Case weight doesn't always provide a reliable indication of volume, which is what affects pressure. That is what we're trying to make consistent for consistent velocity. Sorting by casehead is a good place to start. Other than that, if you're shooting past 400 yds AND doing everything else possible to the case (trimming to length, uniforming primer pockets, deburr flashhole, turning necks) then start worrying about case volume.

But even for "precision plinking" I think you're wasting time weighing cases since the weights you quote are less than 2% variance.

 

[Hoodlum]

Understood..... Thanks....

 

[buffybuster]

Weight sorting is using an INDIRECT methodology to determine case volume; based on the ASSUMPTION, if the outside dimensions are the same, then weight and volume have an inverse direct relationship. While it may hold true in large systems; to the degree of precision reloaders are measuring, this assumption does not hold consistently.

The best way to measure volume is to measure volume, but we can be very nearly as precise by measure volume to mass. Might take a bit of time, but with random sampling (SPC/SQC), you can with a high degree of confidence know what the volume and consistently of your cases.



Get a random sample of cases (start with 5pcs each), load and fire them in your rifle, do not resize, do not de-prime, trim those cases to the same OAL, tumble clean. Place cleaned case on digital scale with 0.01 GRAMS minimum resolution. Use a small dropper to fill the case with clean water to the casemouth with concave meniscus. 1gram of pure water equals 1ml. Tap water is "pure" enough for our purposes. You will quickly determine how consistent your cases are. This will provide a DIRECT methodology to measure case volume.