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# Bullet batch weight variation

#1
07-25-2009, 02:38 AM
 Platinum Member Join Date: Nov 2008 Posts: 1,087
Bullet batch weight variation

With a crook batch of projectiles. How much of an effect on point of impact would you expect per 1 grain of variation in bullet weight?

Example, if a sample of 10 bullets were weighed and the bullets varied in weight from 248.5 grains to 251.5 grains. ie 3 grains variation. How would this effect point of impact at 1000 yards?

Be interested to know as I have a few boxes that are just like this and cant send them back.
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#2
07-26-2009, 11:32 PM
 Silver Member Join Date: Apr 2009 Posts: 195
Re: Bullet batch weight variation

Anyone? Anyone? Bueller? Bueller?

I was wondering as well. I had the same bullets, but could send them back.
#3
07-27-2009, 10:18 AM
 Platinum Member Join Date: Feb 2008 Location: Wampum, PA Posts: 1,530
Re: Bullet batch weight variation

"Good Grouper" would probably have an answer for this one. try shooting him a PM with a link to this thread and ask if he'd be kind enough to post a reply. He is a great resource, and a good fellow but hasn't been posting much lately.
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#4
07-27-2009, 11:37 AM
 Platinum Member Join Date: Jul 2004 Location: Texas Posts: 7,241
Re: Bullet batch weight variation

Quote:
 Originally Posted by Topshot With a crook batch of projectiles. How much of an effect on point of impact would you expect per 1 grain of variation in bullet weight? Example, if a sample of 10 bullets were weighed and the bullets varied in weight from 248.5 grains to 251.5 grains. ie 3 grains variation. How would this effect point of impact at 1000 yards? Be interested to know as I have a few boxes that are just like this and cant send them back.
The percentage difference in weight will be close to the percentage difference in velocity.

It is not much but at long range it could be enough to open up your groups.

For all out accuracy it is recommended that you weight sort your bullets in batches .

If your using them at 3 or 400 yards it will not make that much difference.

If your not convinced you can load 5 rounds with the extreme weight variation (Lowest to
highest) and load 5 that weigh the same and shoot them at the longest distance you feel comfortable with for comparison.

J E CUSTOM
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#5
07-27-2009, 07:33 PM
 Platinum Member Join Date: Nov 2008 Posts: 1,087
Re: Bullet batch weight variation

Quote:
 Originally Posted by J E Custom The percentage difference in weight will be close to the percentage difference in velocity. It is not much but at long range it could be enough to open up your groups. For all out accuracy it is recommended that you weight sort your bullets in batches . If your using them at 3 or 400 yards it will not make that much difference. If your not convinced you can load 5 rounds with the extreme weight variation (Lowest to highest) and load 5 that weigh the same and shoot them at the longest distance you feel comfortable with for comparison. J E CUSTOM
Thanks J E,
I put this question to Bryan Litz after readeding his great new book. Your thoughts pretty much line up with what Bryan had to say.

This is what he came up with....................................

................. "a difference of 2.6 grains is just over 1% variation in weight. Assuming 2900 fps MV, this difference in BC would only affect your drop at 1000 yards by 1.8" (from a 100 yard zero).
That amount of weight variation would produce the same vertical dispersion as an 8 fps variation in MV"............................................... .................

So it seems that with a constant form factor, all you need to do is work out the muzzle velocity variation. Then run the program to work out the trajectory for each of the velocities at the extreme spread. The difference in trajectories is the maximum drop variation, ,maybe?

As you said "J,E", I will only know after I have shot them for comparision.
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