Boolit weight for 12" twist 223

[historicfirearms]

What boolit weights / styles have people has luck with in 12" twist 223? I've got the Mihec 65 gr NATO and soon to have his 75 grain boolit, but I think both of these are going to be too long for my rifles twist rate.

[Wayne S]

It's not the bullet weight but it's length that determines stability. Look at the first thread on the GB for the 311-247, there are three stability programs listed; here is one of them;
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi It's range is 1.3 to 2.0, with the military using 1.5.
It shows a .225 bullet .75" long at 1800 fps having a factor of 1.55. But the only way to be sure is to load and shoot them on paper

[JonB_in_Glencoe]

the short answer is...probably
But on the other hand, you aren't going to lose anything by trying them.


good Luck,
Jon

[historicfirearms]

The jbm stability calculator shows that the 75 grain boolit (.763" length) should be stable at 1800 +fps. I was debating on selling that mold before I used it, but now I'm going to give it a try.

Thanks for the link.

[gmsharps]

I've seen 223 rifles with consecutive serial numbers where 1 would shoot 70gr bullets and the other would not using thesame identical load. Every rifle is different and you just have to try it. The 75 grainer is pushing it for a 1 in 12 inch twist though.

gmsharps

[Larry Gibson]

The 65 gr MP 227-65 (if that's the 65 gr NATO bullet you mean?) is stable in a 12" twist down to around 700 - 800 fps. It does very well at 2000 - 2300+ fps in the 12" twist..

A 75 gr bullet is not stable until around 1800 fps +/-.

Larry Gibson

[Doc Highwall]

Speer made a 70 grain semi pointed bullet along with loads for the 22-250 with a 1-14" twist that would stabilize under 2000 fps so your 65 grain bullet should be ok but you are SOL with the 75 grain with that 1-12" twist.