Is this too much crimp on FMJ?

[serpentine]

Dies are setup for Lead Round Nose. We picked these up and noticed that after seated and crimped the jacketed rounds could be twisted. I could not pull by hand, but the rounds will rotate in the case. After pulling this is what we saw.

Is this too much crimp?

[pennlineman]

Way too much. When you bell your cases, do so just enough to prevent shaving the bullet or damaging the case. The tension between the case and the bullet will help hold it in place. Apply just enough crimp to remove the bell and you should be OK. Just make sure the bullet won't push back into the case. If it does, apply a little more crimp. Baby steps. If you do it right, you won't distort your bullets.

[serpentine]

Thanks! Do you think that it is too much crimp on the lead bullets as well? I pulled a few of those and I see no deformations. I am assuming that the lead is much harder than the jacketed bullets.

[pennlineman]

The lead bullet should actually be softer, being nearly the same diameter. Lead bullets are usually sized a thousandth or so larger than jacketed bullets. I can't see how they escaped being deformed as well. Unless your dies somehow got adjusted since the last time you used them.

ETA: The ogive shape of your jacketed bullet may be longer than the lead bullets you were using. If you did not adjust the depth at witch you are seating. The longer profiled bullet would be getting crimped before it is fully seated.

[serpentine]

Your first assumption was correct. My buddy and I load together, and he just informed me that he has significantly backed off the crimp since he set those jacketed rounds on Sunday.

Our lead rounds came out real nice last night, and hopefully, the jacketed rounds will come out just as nice without the need for adjustment.

Thanks for your input. Much appreciated.

[Grumpa72]

This is OVERKILL to the extreme. When I crimp a bullet, whether lead or jacketed, I can take them apart with a kinetic, or hammer, puller and you won't see a mark on them. My occasional pulls can be reused. Yours cannot.

[hornady]

Are you sure these are jacketed bullets, and not in fact a plated bullet. As said above jacketed are much harder than cast. Plated bullets in some cases are softer than cast bullets. With a Thin plating over a soft lead core. Plated bullets should not be pushed much above mid range jacketed loads.

[SauerGrapes]

That kind of crimp can also cause spikes in pressure, which is never good.

[serpentine]

Yes, they are FMJ.

[dkf]

You are WAY past a crimp there, you swaged the bullet. I bet a load with that much crimp is highly inaccurate also. You could spin the bullet in the case because the crimp ruined the neck tension. People think the crimp helps neck tension when it is actually the opposite.

On an FMJ there should be a slight ring/mark on the jacket but no bullet deformation. You will need even less on cast or plated bullets. You just want to get the flare (put on the case mouth to help seat bullet) out of the case mouth with the crimp.