keyholes

[trb0]

I have a savage model 10 shooting 168 gr. hdy match bullets at 2700 f.p.s. that regularly shoots 1/2 inch 5 shot groups at 100 yards. I tried shooting at 850 yards and the bullets were keyholing. I moved back to 300 yards and still keyholed.Back to 100 perfect bullet holes.Back to 340 yards perfect holes. Back to 300 yards and now I get some keyholes and some good holes.I did just have a muzzlebrake installed and seating depths vary between .005 out of the lands to just touching the lands, this being the only changes made before getting the keyholes. Any ideas as to what to check? thanks trb0

Well...let's talk about Sierra 168's if you're shooting .30 caliber, since I don't shoot the Hornady! The 168 gr. Sierra has a 13 degree BT and it was DESIGNED FOR 300 METER SHOOTING, not long range! Any bullet that has this angle of BT has the same drag function as a flat based bullet which.....ain't burning the patch up for accuracy at LR! The 168 Sierra in .30 cal. at your velocity goes "tits up" for stability at 800 yds. and it was quite common to see shooters pulling their hair out and scratching their arses trying to figure out what was going on when they were attempting to use this bullet from 1000 yds. as they were getting misses and the bullets were coming into the target frames with a perfect side profile aka keyhole!! Change over to the Sierra 175 grainer and at the same velocity as the 168...it will be good to go!! [img]/ubbthreads/images/graemlins/grin.gif[/img]