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GENERAL => CZ Custom => Topic started by: loader on August 28, 2013, 03:40:25 PM

Title: Tumbling Projectiles
Post by: loader on August 28, 2013, 03:40:25 PM

I get tumbling projectiles out of my Shadow at times. Going side ways through a target at 12 feet. Not sure why it comes and goes.

Frontier 147gr FN
Clays powder (fast burn rate side but soft recoil)
oal 1.11
Almost no crimp just removing belling from powder charge.
PF 133

Any Ideas?

Title: Re: Tumbling Projectiles
Post by: rodolfo on August 28, 2013, 04:32:23 PM

What is the bullet's speed?  If it is above the sound barrier at the muzzle and below it at the target the bullet may tumble when it goes sub-sonic.  With 147gr that would be a pretty hot load.

Title: Re: Tumbling Projectiles
Post by: 1SOW on August 28, 2013, 04:36:44 PM

133 PF is 905 FT/SEC with 147gr bullets.  Should be a good comp load.
loader, have you tried other 147's?

Title: Re: Tumbling Projectiles
Post by: loader on August 28, 2013, 05:16:33 PM

No I have stuck with the Frontiers and have 25k-30k to go. It seems to happen when I change from one batch of brass to another. Which makes me think of crimp? The last time I fixed it I changed a few things at one time (in a rush) so I'm not sure which was the fix :-\

Title: Re: Tumbling Projectiles
Post by: 1SOW on August 28, 2013, 06:29:03 PM

The powder 'may' also have an affect.  A faster powder is what competitors normally use for soft recoil with heavy bullets.
Just a thought.

Title: Re: Tumbling Projectiles
Post by: IDescribe on August 28, 2013, 06:59:15 PM

Loader, I have read (not experienced) in the past that 9mm can sometimes have tumbling problems below ~925 feet per second.  If you can safely increase the charge by .1, .2, .3, etc., try that and see if it goes away. 

Title: Re: Tumbling Projectiles
Post by: angus hobdell on September 01, 2013, 04:58:13 PM

try catching one in water, I bet there is not much plating left on the bullet.
I stay away from all plated bullets.

Title: Re: Tumbling Projectiles
Post by: jabbermurph on September 01, 2013, 05:01:15 PM

I have loaded Berry's and Xtreme 147gr with no problems.  Try a longer OAL...around 1.140 with a crimp of .378-.380.

I load with 3.4-3.5 of n320 at around 130pf

Title: Re: Tumbling Projectiles
Post by: angus hobdell on September 02, 2013, 02:47:16 PM

You can also check the crimp bu pulling a  bullet after loading it and check for an over crimp witness mark.

Title: Re: Tumbling Projectiles
Post by: loader on September 21, 2013, 05:18:14 PM

Angus is right ....I reduced my crimp (even more) and tumbling is gone.
It must have been striping the copper off the plated Frontier projectile (reducing diameter) which in turn reduced the spin on the projectile which = tumbling.  :P

Title: Re: Tumbling Projectiles
Post by: angus hobdell on September 23, 2013, 05:48:13 PM

Nice glad you found out what was causing the problem.
When yu damage the bullet like that with the crimp, it rattles down the barrel because the bullet dia is smaller r:-)