Hornady Brass Weight: Interesting finding

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pacobillie

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I recently bought 100 once fired casings of Hornady Brass in 7mm Rem Mag to resize to 257 Weatherby.

After getting some erratic velocities, I checked out the weight of the cases. I found out that there are three groups of cases, according to weight:

About 7% weigh around 215 gr, +/- 1.5 gr
About 73% weigh around 234 gr, +/- 1.5 gr
About 20% weigh around 256 gr. +/- 1.5 gr

What is most interesting is that there are no in-between weights. This seems to indicate that the cases were made thinner or thicker on purpose. Why would Hornadu do that?

I have now sorted out the brass and plan on shooting only those cases weighing around 234 grains.

BTW, cases were weighted before cleaning and depriming.
 
Probably the wrong weight of brass used for initial case forming. I picked up some factory 270 out of the range bin, it all weighed less the 308 Winchester brass and looked like it would separate if it was reloaded once.
 
Maybe illustrates the issue of using weight as an indicator of case volume - weight would work, if the alloy density is always the same. No real reason to know that is so. The pressure developed, as I understand it, is related to the actual interior volume of the case, and people weigh cases in preference to actually measuring the volumes. But that relies on the brass density always being the same - which it may not be. Since you bought once fired cases, you will have no way to know if they were actually from the same production lot - could have been cases made across many years.
 
Two boxes of Dominion 30-06 brass.
#1: 186 - 203 grains
#2: 183 to 206 grains.

Some place in the middle I found 20 with 5 grains variation.

Norma 6mm Rem Brass. Two boxes with a variation of 1.1 grains.

That was over 50 years ago.

Weighing brass is not a matter of life or death . . . it is much more important than that!
 
Weight sorting is meaningless unless you neck turn, primer pocket uniform and flash hole deburr, and possibly dress the rims of the cases first.

A truer test of consistency is to do water volume comparisons of the cases.
 
Lefty #### said:
Weight sorting is meaningless unless you neck turn, primer pocket uniform and flash hole deburr, and possibly dress the rims of the cases first.

A truer test of consistency is to do water volume comparisons of the cases.
Click to expand...

How do you measure water volume reliably, making sure that there are no air bubbles trapped inside the case?
 
Yeah, that is a bit much of a spread... I suspect, multiple machines or multiple runs merged into the same bag. In general, if all brass is one lot, same machine, weight can vary a bit but case volumes are nearly identical...BUT consistency in weights that far apart, indicate merger of various lots.

If you want to go through the effort, separate the cases into weight groups BEFORE firing. After firing, compare case volumes.. I use a very fine ball gunpowder (H110 is similar).. or salt.

Fill to the brim taping the case to ensure it is well compacted... dump into the next case, tap and see relative position of contents. Within 1mm in the neck, I don't care about... most will be pretty much spot on. If you can big differences, under OR over (so becareful about spillage), separate those cases.

With large case volumes and stick powder at moderate load densities, case volume variations may not matter on target.... but at least you have a base to compare properly

Good luck.

Jerry
 
Mystic Precision said:
If you want to go through the effort, separate the cases into weight groups BEFORE firing. After firing, compare case volumes.. I use a very fine ball gunpowder (H110 is similar).. or salt.

Fill to the brim taping the case to ensure it is well compacted... dump into the next case, tap and see relative position of contents. Within 1mm in the neck, I don't care about... most will be pretty much spot on. If you can big differences, under OR over (so becareful about spillage), separate those cases.

Good luck.

Jerry
Click to expand...

Thanks for sharing that Jerry.

Regards
Ron
 
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