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39 BK's hitting target sideways
Posted: Wed Mar 24, 2010 4:12 pm
by Pepe-Lepew
I need some suggestions to solve a problem. I tested several loads of 39 BK's and reloader 10x. The loads ranged from 23.3 to 26.0 grains with an OAL of 2.250 and were shot through my CZ 527 varmint. Velocities range was 3326 fps for 23.3 grains and 3713 fps for 26.0 grains. Some bullets in five shot groups, of loads above 23.6 grains, completely missed the 3 inch target at 100 yards. I wondered where they were going, then noticed holes in the paper of a bullet profiles. Near max loads did not even hit the 3 inch target, of five shots. After shooting the BK's, I shot 80 rounds of 40 grain V-max's and H4895 with good groups
. Why do you think I am having a stability problem with BK's? Would increasing the OAL cure this?
Re: 39 BK's hitting target sideways
Posted: Wed Mar 24, 2010 4:23 pm
by Song Dog
When I had my CZ, I had the bullets out just enough, so they fit in the clip. It shot the 39s great.
In Christ,
Song Dog
Re: 39 BK's hitting target sideways
Posted: Thu Mar 25, 2010 7:27 am
by FireBallGuy
Agreed song dog! Seat them bullets out!
Re: 39 BK's hitting target sideways
Posted: Thu Mar 25, 2010 6:40 pm
by jo191145
Increasing OAL may help accuracy. It will NOT stop tumbling.
If the 40 V-Max are shooting fine its not a stability problem.
Most likely your compromising the jackets of the bullets.
The 39bk has the softest jacket/core construction of any 204 pill I've tested.
I've seen this problem in not only my factory barrels but an aquaintences custom tube as well.
10X is a rather dirty powder at least in my expierience. I know many have good luck with it. I've seen it shoot some impressive groups myself. After 40rds or so without cleaning those groups go absolutely haywire (in my expierience).
Good chance you rapidly built up a carbon ring and its squeezing the 39 and causing friction the jacket cannot withstand.
Think I'm nuts?
Thats what we found in that custom tube using 10X and 39's with a borescope after it started tumbling. A 4'' long layer of hard carbon with silver streaks in the bore.
Only one thing I know of that can cause silver streaks in a barrel. Molten Lead! Ever hear of comet trails in relation to compromised jackets? It happens.
Best advice, clean the ever living snot out of that barrel and try again with your H-4895.
If they still tumble its just one of those things. I've had two factory barrels that tore them things up no matter what I did. Everything else shot just fine. Good Luck