Combo crimping ?


October 2, 2012, 10:48 PM
I'm stuck loading some 357 mag R-P cases Nosler 158gr JHP with CCI 500 and 13.7gr of AA#9. The R-P brass gives the least neck tension of any brass I have, I normally use the this brass with .358 dia. lead bullets.
To prevent bullet jump with this R-P Nosler combo I seat and crimp in two steps, and that works well but it requires some extra adjustments.
I did a test batch of 25rnds with a heavy roll crimp that slightly buckled the case mouth and then used a 9mm/38spl Hornady taper crimp die to iron out the bulge. My brass is trimmed to 1.280" I'm anxious to see if this works.

Has anyone tried this or a similar method ?

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October 2, 2012, 11:55 PM
do the loaded rounds fit in your chambers? if they do, load six, fire five, then measure the cartridge length of number six. if it gets longer, you need to get more case tension on the bullet.

see if your 9mm sizing die will work on the 357 cases. you may get a bit more tension on the bullet that way. you only have to size as far down as the bullet will go, not the whole case.


October 3, 2012, 06:48 AM
No. I've always tried what ^ he said, first. And I've never had bullets jump out of the case. You're fixing something that might not be broken. :)

I know what you mean about R-P, though. I have some .38 cases that you can push the bullets in/out of a sized case by hand. I still use 'em, just roll crimp like normal into the crimp groove or overtop a wadcutter.

October 4, 2012, 12:12 AM
You're fixing something that might not be broken.
The bullets are jumping from recoil with this brass bullet combo. I'm trying to stop this with a different crimp technique.
This is only a issue with R-P brass and the load I described.

October 4, 2012, 08:40 PM
RP brass tends to be thinner than other brass. That makes it excellent for lead and lower pressure loads, but neck tension on jacketed bullets suffers.

October 7, 2012, 01:39 AM
Well the combo crimp didn't hold the bullets :( Fired five and the one left jumped .005"
I know better but I thought I could outsmart the R-P brass :banghead:

October 7, 2012, 01:50 AM
Try a Lee Universal expander. It only bells, so you get maximum case tension on the bullet.

October 7, 2012, 05:02 PM
^ Waste of money. The R-P cases don't have enough tension, even without belling, short of ordering a custom undersized sizing die.

They're shorter, too. So when you flare mixed cases, the R-P are hardly being touched. You can tell when they go through the flaring die. Just take 'em out and use them for a moderate load with a cast bullet with a real groove.

October 7, 2012, 09:29 PM
First, don't waste any more time using RP brass. Give it to someone you don't like. Measure your expander plug. If it is not 4 or 5 thou. under your bullet dia. then you are over expanding the cases. You can turn it down in a drill if it is oversized. To have sufficient case neck tension you should be able to see the outline of the bottom of the bullet through the brass when seated. Heavy crimping will not stop bullets pulling. Good case neck tension will. Seat a bullet but don't crimp it. Press it against the edge of your bench as hard as you can. It should not move. If it moves any at all you need more tension.

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