9mm more crimp?

[Red9]

There's a bit going on here.



It looks like the case mouth too much flare. You only want enough bell/flare so the base of the projectile can sit in the case mouth, and you can seat the projectile without gouging the copper. Seat a projectile and pull it without crimping to check.



Have you tried chambering those rounds with the full force of the slide spring? If you have too much crimp the cartridge will lodge itself into the chamber and be difficult to extract. The 'plunk' test won't demonstrate that. Remember 9mm headspaces off the case mouth. The case mouth is VERY important for setting head space and sealing the brass to the chamber when firing. Proper flare will also preserve your brass and get you several more loadings out of it.



If you look carefully at some of your samples you can see the case mouth pulls away from the projectile and there's still remnant of parabolic curvature below the case mouth. This indicates more an issue with flare than crimp. You do NOT want to solve this with more crimp.



You need to get the flare issue fixed prior to adjusting any part of your process for crimp. When the flare is proper the seating of the projectile will remove 90% of the flare. The 'crimp' is a bit of a misnomer with 9mm, you're really trying to remove an remaining bell so the case mouth is flush to the copper jacket or plating.

I'll back off the flare a bit.

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[Red9]

I don't use plated. Either fmj, tmj, or PC lead at .357.
Yes I use a case gauge. I crimp until it passes a case gauge. And check about every handful or so out of the bin.
No set back btw.

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[ysr_racer]

You guys keep saying "set back". Do you really mean "bullet creep"?

[jayhuh]

You guys keep saying "set back". Do you really mean "bullet creep"?

[Red9]

Agreed.
Bullet creep is not good in revolvers. I do heavy crimp my Magnum straight walled. Seen a guy at the range had a lock up..not pretty.

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[ysr_racer]

Yeah, I guess it could be both

[AJD]

All the crimp in the world will do little to nothing to prevent bullet setback. And as mentioned above, too much crimp can hurt. Proper case neck tension from a properly resized case provides protection against setback in a case like 9mm, not crimp. In semi auto calibers like 9mm, 45ACP etc, using just enough crimp to remove the bell from the expander is all that's really needed.

[Donny1]

Yes, many will chide you for crimping straight wall cases at all. I think they are the same people that scream out loud when you say you load your own SD ammo.

[pacrat]

Yes, many will chide you for crimping straight wall cases at all. I think they are the same people that scream out loud when you say you load your own SD ammo.

Says the same guy who "roll crimps" cartridges that headspace off the case mouth.

[ysr_racer]

I use a Lee U (undersized) die for 9mm. It gives me more case tension.

[bohoki]

they look ok to me maybe could use less

[ar15barrels]

I'll back off the flare a bit.

After you do that, set the crimp die so it just eliminates the evidence of the previous flaring.
You don't need to actually be crimping the case so far into the bullet that you are denting the bullet.

[Red9]

Yes, many will chide you for crimping straight wall cases at all. I think they are the same people that scream out loud when you say you load your own SD ammo.

What wrong with a heavy crimp on straight walled? My 44 factory bear loads, have a extreme crimp?
Also what's wrong with self made sd ammo? If one uses the same head stamp how would they know? I.e. federal brass with a federal projo?

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[Red9]

I use a Lee U (undersized) die for 9mm. It gives me more case tension.

Giving the standard lee die a try before I get a undersize die. Thanks for that Intel.

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[Red9]

After you do that, set the crimp die so it just eliminates the evidence of the previous flaring.

You don't need to actually be crimping the case so far into the bullet that you are denting the bullet.

Yes I try not to crimp into the projo. Usually just enough to take the flare out. .377 or so, it's not the .380 like the book says. My fingernail says it's still a bit belled? But the caliper says otherwise[emoji29]

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