Mixed headstamps


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Steve Marshall
February 12, 2011, 07:41 PM
This post is not designed to cause palpitations on the same headstamp sorting crowd. But many of us load with no thought or worries about mixed headstamps. The eye opener for me came when I was cleaning corncob out of the flashholes of 30 Carbine. I was struck by the variety of markings. So I counted out 100 cases and came up with no less than 14 different ones. Similar with 9MM @16 different headstamps. .308 and 38 Spl were tame in comparison @ 7 each. Nothing earth shattering but I did find it amusing whan comparing to threads that sort and weigh and measure primers and weigh powder to the tenth. I guess I'm having too much fun having fun.

PS I once sorted, weighed and measured OAL on 219 9MM cases scrounged from the range. There were 30 distinct headstamps with a weight of 50.2-63.1 grains and an OAL range of .739" to .752".

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243winxb
February 12, 2011, 07:56 PM
And the moral of the story is ? Let me guess. If you want poor accuracy and problems, use range brass??

BeerSleeper
February 12, 2011, 08:08 PM
This thread needs a purpose.

twofifty
February 12, 2011, 08:49 PM
What caught my attention is the small variability in case lengths between 219 cases with 30 distinct headstamps as measured by Steve: Only .013".

Per Lyman, SAAMI case length is 0.754".
All of Steve's fired cases were shorter than SAAMI, by as much as .015" and as little as .002".

A very quick (not statistically valid) sampling of my mixed 9mm brass shows similar results before resizing. Resized cases are longer by approx .01", reaching a perfectly acceptable 0.750", or .004" less than SAAMI. This is well within reach of the firing pin.

Others?

k4swb
February 12, 2011, 09:41 PM
This thread needs a purpose.
Boy that would sure cut down on posts.:banghead:

Steve Marshall
February 12, 2011, 09:41 PM
Well golly! Maybe we now have a purpose?

243winxb
February 12, 2011, 11:09 PM
I once sorted, weighed and measured OAL on 219 9MM cases scrounged from the range. There were 30 distinct headstamps with a weight of 50.2-63.1 grains and an OAL range of .739" to .752". I think the weight difference is good to know. 12.9gr WOW How can brass be at SAAMI specification and be that different in weight.

twofifty
February 13, 2011, 12:09 AM
Isn't SAAMI a size spec (outside), to ensure safe chambering?
I don't think it has to do with case capacity or case wall thickness.

ReloaderFred
February 13, 2011, 12:56 AM
Case weight tells you nothing, other than the fact that one case weighs more, or less, than another. It doesn't tell you if the weight difference is in the case walls, base or extra length.

I just finished weighing about 400 .40 S&W cases to swage into .44 caliber bullets. All it told me was that I had to vary the weight of the cores before swaging, but nothing about the case capacity. Only water volume will tell you that.

Hope this helps.

Fred

medalguy
February 13, 2011, 01:46 AM
I suppose you do need to sort and load all alike if you're going after maximum accuracy in your ammo. However I shoot for fun mostly, and I have several machine guns I load for, so accuracy in these is not paramount. I don't bother separating brass for these loads, nor weighing powder. I load a midrange charge with a measure. For accuracy loads, yes I do separate, weigh cases, trim accordingly, and weigh powder loads.

gamestalker
February 13, 2011, 03:04 PM
My attention was drawn to the remark about weighing powder to the tenth of a grain. I always use tenths of grains and it doesn't make me feel as though I'm obsessive compulsive, should it? Maybe I need to talk to someone if I'm weighing tenths of grains of powder.

Bananna bore
February 13, 2011, 05:49 PM
Unless your aspiration is to win BR comp or bullseye, less than anal paper punching is OK with mixed brass. Keep the temptation of killer-max-loads in check and you should be OK. I have been loading a wide assortment of calibers since 1975 and have found that if you batch trim to a min length every so often, store your primers and powder in a temp stable environment and use high quality lead- your loads will pretty much do 90% + of what brand/headstamp sorted loads will do.

1SOW
February 14, 2011, 01:32 AM
For pistol, I sort headstamps, because my press seats .004+" deeper in soft brass than harder brass.
My son runs a progressive press with mixed headstamps and 'loose' QC standards; and when I shoot his pistol it shoots as well as mine (inside 25yds).

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