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9/24/2010 3:25:55 PM EDT
My son is doing a project in his high school science class. He wants to compare various (.223/5.56 caliber) bullet weights against various rifling twist rates. I know what weights are optimal for each twist rate, but he wants to show when the bullet is too heavy how it is unstable and inaccurate. My question is if it would be dangerous to shoot 75-77 gr. projectiles out of a 1:12 barrel... I know they will be inaccurate, but is that the only concern? We have rifles available with 1:12, 1:9, 1:8 and 1:7 twists and bullet weights from 55 gr. to 80 gr. Comments or suggestions are appreciated.

1DD
9/24/2010 4:31:12 PM EDT
[#1]
Shouldn't be a problem.  Would be really cool to hire out someone with an ultra slow motion camera so you can see the bullets start to wabble/tumble.  The only scientific data you will be able to show are key holes in paper and POI differences without the camera.  Check out your local Universities RTF programs and see if any of them would want to help you out and maybe do a project on it themselves.  If you do, be sure to post pics, videos.
9/25/2010 3:03:04 AM EDT
[#2]
Thanks. Unfortunately, the only colleges and universities around here are ultra-liberal. I would not expect to get any positive response to my inquiries...

1DD
9/25/2010 10:04:31 AM EDT
[#3]
Not dangerous to you, but make sure you have an adequate backstop. Shooting heavy round out of a 1:12 will cause them to flutter out of control and they may veer quite a ways off-target.
9/25/2010 12:45:37 PM EDT
[#4]
Good point. Our backstop and downrange danger area is very large and remote, so no worries there.

1DD
9/25/2010 1:18:39 PM EDT
[#5]
Go down to 40 grn too. They may provide suprising results. If it ends up being boring data he can just leave that end of the spectrum out. I would also either try to use all the same brand and style of bullet or use 3-4 examples of each weight. That would give him a better sample than a brand X of this weight and brand Y of that weight.

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