Oh, one more point.
223/5.56mm rifles come with all different sorts of rifling rates.
The original 1 in 12 rate will stabalize the old military 56 grain spitzer boat tail bullet (M196 load) or up to a 60 grain spitzer flatbase bullet or the old Speer 70 grain round nose bullet.
Ruger's 1 in 9 rate will stabalize bullets up to about 70 grains in weight but nothing much heavier.
The 1 in 7 twist on the military's rifles and the Colt HBAR will stabalize even the long 80 grain Sierra Match King and even the heavier tungston cored bullets.
Check your rifling rate per the manufaturer or by the old cleaning rod method to ensure that you are not using a bullet heavier than your rifle can stabalize.
US Army Distinguished Rifleman
Washington State Distinguished Rifleman
NRA Police Distinguished Expert
Last edited by Scharfschuetzer; January 31, 2012 at 11:57 AM.