9mm more crimp?

[Red9]

More crimp or just send them?
Passes plunk test fine. My OCD tells me more crimp. The book says it's fine.
115 pill 4.5gr 231 col 1.10.

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[Strafer]

I load 115gr xtreme FMJ RNs over 4.9gr of 231 and a COAL of 1.114. That COAL works for all my 9s. If the completed cartridges pass my 9mm case checker, then into the pistol they go.

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[tabascoz28]

How do you know it's not enough? Better a little too much than not enough. In case you have to clear for a cease fire.

[racinjason233]

Use a micrometer to check the crimp. The specifications are in the book. 9mm case headspaces on the chamber rim. Don’t add more!

[roggiedog]

.378 seems to work fine for me.

[Red9]

.378 seems to work fine for me.

I'm right there. .377 to .378

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[Raiderh20boy]

All mine come out .378-.379. No problems

[hermosabeach]

Bring calipers to range

Measure coal

Fire 4
Unload
Measure remaining rounds you unloaded
Did the round you chambered move?
Rounds from magazine that bounced with recoil- did the coal change?

If coal did not change - you have enough crimp or tension

[pacrat]

How do you know it's not enough? Better a little too much than not enough. In case you have to clear for a cease fire.

Not True.

Neck expanders are a few thou smaller dia than bullets for a reason. "INTERFERENCE FIT". Makes the bullet tight in the neck.

Case brass has inherent spring back. Lead does not. The brass resists the bullet being pressed into the neck. So it stays tight.

If you "over crimp" you actually loosen the bullet in the case. Because you reverse the process. You squeeze the neck AND bullet smaller together. Springback of the case neck leaves the now smaller bullet without the "interference fit" neck tension to hold it.

Properly straightening the case mouth, just enough to remove the bell, after seating is all that is required, or desired, on all straight walled rimless cases.

[Fizz]

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.

[NeilMo]

"Passes plunk test fine"



Send em!

Too many people on here overthinking this.

[Donny1]

I just crimp enough to "slightly" roll the edge, never had setback issues. I have chambered the same round 10 times and got maybe .001-.002 setback.

Seat and crimp, then push it against the bench real hard and see if you can reduce the COL, if not they are GTG. Many don't crimp pistol cases at all.

[ysr_racer]

Buy one of these chamber checker's

https://www.egwguns.com/case-gauge-ammo-checker-9-mm-7-hole

[jayhuh]

I just crimp enough to "slightly" roll the edge, never had setback issues. I have chambered the same round 10 times and got maybe .001-.002 setback.

Seat and crimp, then push it against the bench real hard and see if you can reduce the COL, if not they are GTG. Many don't crimp pistol cases at all.

I just usually crimp and check like above till I don’t get any setback. I randomly check the finished rounds in a case gage but that’s more to check for bulged cases at the base which can cause a pistol to not go into battery and is sometimes hard to clear. I’ve been loading since 1982 and I don’t recall ever having my gage reveal a case not crimped enough.

As for using a micrometer to measure the case mouth I don’t have a micrometer. I do use a caliper which I use for COL. But if you do measure finished case mouth, keep in mind that different brands of cases will show different measurements.

Also if you are using plated bullets you have to be careful not to over crimp as it affects the plating which will affect your accuracy. Every plated bullet manufacture warns of this. Good luck..

[Red9]

Bring calipers to range

Measure coal

Fire 4
Unload
Measure remaining rounds you unloaded
Did the round you chambered move?
Rounds from magazine that bounced with recoil- did the coal change?

If coal did not change - you have enough crimp or tension

Now that's a cool tip!

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