06-17-2012, 08:13 PM
ChellieWiles Wrote:LR1955,
I'm using a 22" JP cryo supermatch barrel with H322 powder in Lapua 6.5 Gren Brass and CCI small rifle magnums-#450. Upper and bolt is also JP and all bolt components are QPQ finish. Bullets are seated to .002" below mag length. Loads are hand weighed to 28.8grains of the H322 with the 108's. I've been questioning others as to why they aren't using this powder with bullets in the 100 grain range as the only pressure indicators i'm getting are slightly flattened primers...no cratering until I reach about 29.7 grains with the scenars. You can go to 30.4gr with the 100 ttsx's before cratering begins but I like the 2800-2850 velocities. I have noticed that if you push this powder too much (upper limit of the loads i'm posting) there is yaw, precession and nutation out to about 75-80yards but then stabilization if you are over 2950fps.
link to what i'm talking about
http://library.med.utah.edu/WebPath/TUTO...NBLST.html
but, if you keep the 100-108's around 2800-2850fps, there isn't any of that.
CW:
Just a note.
You can't have both nutation and precession at the same time.
I will let someone else try to get 2850 from a 108 Lapua out of a gas gun. Nothing special about the JP. I have one but won't attempt to replicate this test.
I did hit 2700 with a 120 Sierra out of an Overwatch one time. Can't remember the load but it was up there. Shot one round and stopped. I also got about 2750 from a 107 Match King using Reloader 10X. That time I shot about ten rounds before stopping. Both had a weird sound, weird recoil. The brass (Lapua) was toast.
LR1955