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darestie
October 24, 2012, 12:35 PM
My Olympic SUM .223 upper has been doing fine with 55gr ammo but I'm curoius if I can get better accuracy out of a lighter bullet. It's a 20" 1 in 10 twist barrel. I picked up some Fioochi extrema with the 40gr Vmax bullet rated at a crazy 3650fps! I'll give it a shot and see how it shoots.

In general though, what is the range of bullet weights that stabilize in a 1 in 10 barrel?

Jimro
October 24, 2012, 02:23 PM
I wouldn't try anything heavier than the 68~69 gr HPBT bullets. But I would try them. You might find good accuracy with the 62gr projectiles.

Jimro

Art Eatman
October 24, 2012, 10:26 PM
I inherited some reloads with a round-nosed 70-grain bullet. Sub-MOA in a 1:10 twist barrel. And while not optimum for the weight, 40-grain bullets should group okay with that twist.

moxie
October 25, 2012, 10:11 AM
The 55 and under should be fine with the 1:10. Heavier than 55 really wants a faster twist, which is why we went to the 1:7 with the 62 grainers in the military. But that's just a rule of thumb. As noted above, some guys get excellent resuts with 70 gr. and 1:10. Try different weights and bullets and see what works in your gun.