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Old March 4, 2011, 05:33 PM   #1
twins
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Weighing bullets..anyone?

Normally, I do not sort/weigh bullets before reloading. But this time I decided to see the variance between the weight of the bullets in the same package. I was sorting through a package of 100 Prvi 55 gr SP bullets (.224) for a p-dog load and found the lightest weighed 54.1 gr and the heaviest was 55.7 gr. The majority (about 2/3) of the bullet came in at 54.6/54.7. Only 16 came in at 54.9/55.0.

Is this about normal?

Anything to be concerned about if the weight is within +/- 1 grain?

Thanks.
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Old March 4, 2011, 05:55 PM   #2
PawPaw
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We guys who use cast bullets routinely weigh bullets for top accuracy. I'll take a batch of bullets and sort them by one standard deviation. A batch of bullets normally approximates the standard distribution that you learned about in statistics class. There's a good article explaining the process under this link.

Several years ago I bought a batch of blemished HPBT bullets and I've also sorted them by weight. I was astonished to get almost three grains between the lightest and heaviest bullets, so I put like weights in small zipper bags and load them in batches with like weights.

Weighing bullets is not unheard of.
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Old March 4, 2011, 09:13 PM   #3
FrankenMauser
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I weigh bullets occasionally, but it's normally just out of curiosity. I don't change my loading practices, based on the results of the weigh.

Most 'average' bullets from 50-100 gr seem to vary 0.3-0.5 grains (some a bit more).

The heavier the bullet, the larger the variation by weight, but the smaller the deviation by percentage.

Premium bullets..... They're a different story. Barnes, Swift, and Woodleigh have supremely impressed me with their consistency. (Often no more than 0.1-0.2 gr variation, even at 180+ grains).
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Old March 4, 2011, 10:06 PM   #4
semi_problomatic
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I sort by weight and load in batches as well, but its not weight but concientricty (I KNOW I spelled that wrong!!). Or how even the jacket is. If its thicker on one side than the other then the bullet will wobble throughout its rotation. This plays a bigger impact than the slight deviance in weight. Though you may have a difference in fps over a crono (no more than +- 5 fps, I'd imagine) due to different weights if they're extreme. IE 2-3 grains.
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Old March 4, 2011, 11:40 PM   #5
ltc444
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consistent bullet weight = accuracy

A number of years ago I read an article, Guns and Ammo I think, were the author weighed 22 long rifle bullets. He found: 1. Considerable variations in bullet weights. 2. The greater the deviation in weight the greater the spread in the pattern. 3. He used those within .1 grain of each other for his matchs. 4. His match scores improved dramatically.

Based on that article, I weigh my bullets, group them and develop loads for each group.
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Old March 5, 2011, 12:38 AM   #6
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I generally only weigh and separate what I use for long range shooting--.2gr variance doesn't mean much for a couple hundred yards on a whistle-pig. It means a hellofa lot at 1000 meters. If I'm loading 90gr. FMJ/BT in 6mm, every one in the batch is exactly 90gr. They stay on the plate that way.

I also weighed and separated a bunch of mil-surp fmj's for my mosin. I found out of the 1000-round batch the lightest was 143gr. while the heaviest was 151gr. They were supposed to be 147gr. Most were within 1gr. But having load batches matched by weight within .5gr has really tightened up groups even on the old Russian M91.
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Old March 5, 2011, 04:05 AM   #7
semi_problomatic
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Weighing cartridges is next to useless. Weigh your brass next time and see what the differences are. You could have exactly the same cartridge weights and completely different powder and bullet weights from shot to shot. That'd be like weighing two cars and guessing they'd go the same 1/4 without looking under the hood first. That chevette with a v8 and nitrious might beat that yugo with a fat guy driving it and a weight set crammed next to him.
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Old March 5, 2011, 09:10 AM   #8
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Quote:
Originally Posted by semi_problomatic
Weigh your brass next time and see what the differences are.
Heh! This stuff will drive you crazy. I know guys who weigh primers, brass, bullets, everything trying to be absolutely consistent.

You're right that brass is another variable in our reloading hobby and if you're searching for that magical, consistent load then looking toward each component is the way to go. I have marked molds so that I could match the orientation of the mold with the orientation of the brass for max accuracy in BPCR shooting. Then you get into chamber orientation, where the indexed cartridge is loaded into the chamber the same way each time. This stuff will drive you buggy.

Quote:
Originally Posted by FrankenMauser
Premium bullets..... They're a different story. Barnes, Swift, and Woodleigh have supremely impressed me with their consistency.
That's my experience too. I weighed a bunch of Nosler Ballistic-tips one day, and after a sample of ten, had a SD of -0-. SO, being the perverse guy I am, I weighed the whole box of 50. All bullets within 0.1 grain, SD = 0. I was truly impressed.
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Old March 5, 2011, 12:18 PM   #9
serf 'rett
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Funny thing that you would post...

...asking the question, because it was one I was checking last night on some "124" grain 9mm plated bullets. Weighted a sample of ten bullets and got the following:
Average weight: 123.93 grains
Minimum weight: 123.6 grains, deviation from average -0.33 grains (0.267 percent lower than average)
Maximum weight: 124.2 grains, deviation from average 0.27 grains (0.218 percent higher than average)
Standard deviation: 0.189 grains (0.152 percent)
Standard deviation range of 123.74 to 124.12 grains with two bullets below the range and two above.

Given the above calculations and a 25 yard range, I suspect I have little to worry about other than my own pistol shooting ability or lack thereof.
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Old March 5, 2011, 12:37 PM   #10
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Oh yeah and

Pawpaw that weighting 50 bullets is impressive.

(In my couseling training we had another name for it, oc.. something or the other - but it's something I'd easily see myself doing if I had one of those high dollar plug in scales instead of a RCBS 505 beamer.)

I'll remember the brand when I get into rifle reloading.
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