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Old February 20, 2013, 11:11 AM   #1
74camaroman
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Reloaded Weight Question???

I bought 1K rounds of Lake City loads and I was wondering if they all weighed should weigh the same. I have a GRAM scale so I weighed them. I got anywhere from 11.80 grams to 12.09 grams, is this normal or should they all weigh the same?

Seems to me with all things being equal they should weigh the same. Bullet 62gr.,.5.56 brass, primer, powder but different years of manufacture for the Lake City Brass.

Am I right in assuming that all 1k rounds shoud weigh the same on a gram scale?
Thanks for any information, to a seemingly silly question.
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Old February 20, 2013, 11:25 AM   #2
FlyFish
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That's a range of 0.29 grams (equivalent to about 4.5 grains), out of a total of approximately 12 grams, which equates to a range of about 2.4%. Doesn't seem unreasonable to me, and I suspect that most of the variability is due to the weight of the brass. I've heard of some shooters, obviously much better than I, who weigh components and/or finished rounds and segregate those of similar weight for shooting together, so others must see variability as well.

I recall a number of years ago having some problems with powder bridging in my progressive press powder measure such that some of a batch of rounds I reloaded were receiving nearly zero powder. I figured it would be a simple matter to just weigh the loaded rounds and determine which ones had very low amounts of powder, but found that the natural range of variability in bullets (these were .45 caliber handgun bullets) and brass made it impossible. Even the lightest rounds had the right amount of powder when I opened them up. (And, yes, I've since modified my loading procedure to prevent such a thing from happening again).
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Old February 20, 2013, 11:29 AM   #3
emptybrass
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I am so new to reloading that I am still in the reading and learning stage, but I did weigh a selection of new .45 ACP brass that I purchased and found enough variation in weight that I would not use post loading weighing as a quality/safety check. Hope this helps.
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Old February 20, 2013, 11:31 AM   #4
rg1
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That's not too bad with just about 4.5 grains difference in 62 gr. LC rounds with different year cases. The 62 grain bullets can vary a grain or a little more while cases can vary as much as a grain or two especially between years. Powder charges while supposed to be identical can vary a tenth or two also. Cases trimmed a few thousandths longer or shorter can effect weight by nearly that much. So I think that's not too bad and not to be concerned with.
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Old February 20, 2013, 12:27 PM   #5
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Military bullet specs allows a 3 grain spread, though half to three quarter grains is more typical for a single lot. Cases vary with years. Here's a link to an Excel file with 40 samples measured. Under LC he gets 1.7 grains extreme spread for a single year, but 3.5 grains extreme spread for '90-'99. And that's just 2.5 standard deviations. In 1000 rounds with that same date year mix I would expect to find an extreme spread of 4.35 grains difference based on his standard deviation. Powder charge spans of half a grain are not uncommon, either. But in any event, between the different brass years and normal charge and bullet weight variation, this is nothing unusual.
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