Too much Crimp?

dearslayer

dearslayer

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I had to pull a few rounds of 9mm because the primers were not seated in deep enough. I noticed an indent in the plated bullet and now I'm wondering if the crimp is too heavy. The loads shoot fine and accuracy isn't bad ( although I haven't shot them bench rested).should I back it off a smidge?
 

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I just crimp according to the manufacturer's specs. For instance, Campro specifies 0.376" for their 124gr bullet. Just use the calipers and check your crimp diameter and adjust accordingly.
 
Plating doesn't look compromised so I'd say no big deal. I like a good crimp when using plated bullets in autos, setback has caused issues for me in the past.
 
OP, measure 10 rds for overall length, load 10, shoot 5, then Measure the remaining 5 for length to see if they have gotten shorter.
Use enough crimp to stop the setback, but, no more.
 
I would say it’s a bit heavy. You can always load a dummy round and push it against your reloading bench. Adjust the die back and see where it moves, and how it groves, then give it a bit more. I use less crimp on CamPros than Zeros, or to be exact, 1/8 less turn on the die for the same crimp.
 
Is maybe up to you to determine? If you are concerned, load 10 with less crimp - shoot 2 x 5 round groups - did group size / functioning get better or worse, or can you even tell. At some point, you will find where it might make a difference for you and your gear - up to that point is more like "theoretical", than a true issue for you?
 
Looks good to me. Main thing is functioning.

They aren't moving and they aren't breaking the plating. Over crimping can bulge the brass and cause chambering trouble.

It doesn't hurt to adjust more or less and see where they start to get loose but it looks like its working as is.
 
Short answer I'd lean to yes, It might not hurt to back the crimp off a bit... I don't know which bullet you're using, but from my experience with Berry's .452 230gr plated round nose I'd say it's maybe a tad much. Their website says "Do not over-crimp the bullet. Crimping so tight that bullet deformation occurs, or plating is separated causing visible exposure of the lead core will cause tumbling, key-holing, and reduced accuracy".

I think the potential issue is that if you crimp the bullet too much, the plating potential might not adhere to the lead bullet as it travels down the bore. I suppose kinda like ripping the casing off a sausage lol. I've backed off my crimp with these bullets to be minimal. I get great accuracy and absolutely no issues with functionality. I'm using the lee factory crimp die.
 
My approach and practise is 9 mm headspaces off the case mouth and neck tension holds the bullet in place. Set the die so it removes the bell and that should do it.
 
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