Tumbling 9mm

[stormbringer]

I load 9mm for my sons G17 and noted that they were tumbling something awful at this weekends 3 gun match.

Any ideas?


125 gr berrys Hollow point.

Winchester primer

4.2 gn Tightgroup.

 

[RePete]

Usually too much much crimp.

Take a factory round and measure the crimp on it and then set your crimp die to that number.

 

[stormbringer]

How does the crimp affect the bullets?

 

[fisherking]

I would say...check your bullets for correct size.

 

[RePete]

Ask me how I know!

Too much crimp swages down the bullet to undersize.

 

[Cocked&Locked]

Ask me how I know!

Too much crimp swages down the bullet to undersize.

I'm assuming your talking about taper crimp, right? Makes sense though...and you can really iron 'em down on the LNL.....(ask me how I know )

 

[buckbrush]

If you are using a Lee factort crimp die, it is probably your problem.

 

[scoundrel]

Storm whose bullets are you running?
Excel?
Copper wash or jacketed?

 

[stormbringer]

As I said I am using Berrys bullets in this case.

 

[RePete]

Have you measured your crimp yet?

 

[eclam]

Why would using a Lee Factory Crimp die cause a tumbling problem?

 

[buckbrush]

Why would using a Lee Factory Crimp die cause a tumbling problem?

They can actually size the bullet smaller while in the case. Alot of 9mm barrels are .357 instead of the listed .355 . If you are getting leading in a 9mm, it can be from undersize bullets, as well as the often blamed too soft of lead.

 

[stormbringer]

Have you measured your crimp yet?

Nope.........'

What should it be?

 

[Fall Guy]

I'll guess at what may be causing the keyholing besides the crimp issue. (hadn't come across that one)

Dirty barrel or bullet fit.

 

[RePete]

Nope.........'

What should it be?

As I said, take a factory round and measure the top of the case (crimp), then set your dies to that measurement.

I had the same issue with my BHP - too much crimp = bullet keyholing in my BHP 9mm.

 

[hoochie]

Why would using a Lee Factory Crimp die cause a tumbling problem?

one has nothing to do with the other.

 

[WithoutWarning]

Nope.........'

What should it be?

FYIO, I measured a few different brands here and I get the following;
.3760" to .3780".
I make mine .376" - .377". I found anything larger, seems to appear like
it is still belled a little.

 

[Aquaneo]

Why would using a Lee Factory Crimp die cause a tumbling problem?

I have used a lee factory crimp die for my 9mm rounds for my G17 and never had a problem.

 

[Slavex]

resize an empty case, bell it like normal. then after backing the crimp right out, slowly adjust the crimp until it just removes the belling and takes the case back to being straight walled. that should be all the crimp you need.

 

[Fall Guy]

Bump.

Storm, enquiring minds would like to know if you found your problem.