9X19mm Crimp Die vs. 9X19mm (combination) Seater/Crimp Die - Thoughts?

[Bimmer]

Im not sure what dies you have in your station 3 & 4 but my stage 3 seats and removes the bell and my station 4 crimps the neck. This is a standard factory Dillion 4 die set.

I'm using Dillon's pistol dies, three in a set...

The "seat" die in station #3 (on a RL550) only seats the bullet. It doesn't de-bell.

The "crimp" die on station #4 de-bells.

[Bimmer]

This did not address what I said. The 9mm is not straight walled. It is a tapered case. When you bell it, you just messed up the neck tension at the point where you belled it (obviously not the rest of the case -- but remember this is tapered so the case mouth area is the most important)...

There is no way, without expensive equipment, for you to just de-bell using your die. You don't know exactly what the brass was sized to and the neck tension was before the belling to get back to it. Adjusting your crimp die to touch the case and then lowering the die another slight bit, maybe 1/8 turn, will lightly "taper crimp" it and provide a more uniform neck tension.

YMMV and all that.

I think you're still talking rifle cartridges... Straight-walled pistol cartridges don't have "neck" tension, because they don't have necks.

(9mm IS "straight-walled" in the sense that it's not a bottle-neck case like .30 Mauser or .357SIG...)

It's not the case mouth holding the bullet, it's the bullet deeper in the case.

But yes, YMMV, and if what you're doing works for you, then who am I to judge?

[vicious_cb]

I'm using Dillon's pistol dies, three in a set...

The "seat" die in station #3 (on a RL550) only seats the bullet. It doesn't de-bell.

The "crimp" die on station #4 de-bells.

Not sure how your cartridges look but there is def no bell after stage 3.

[PracticalRifleman]

Definitely no neck on a 9mm. But when you bell the case mouth, that is only a small part of the portion of the case that is sized.

However, yes you do need to have bullet tension to keep the bullet from dislodging from inertia during the feeding process and the force of the slide slamming home. I’d you do not have enough tension, you can create extreme pressure spikes that could cause damage to the pistol and injury the user.

If you load a case into the chamber 3 times and it grows, perhaps a little more “crimp” isn’t a bad thing. If not, you’re doing fine.


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[Bimmer]

Not sure how your cartridges look but there is def no bell after stage 3.

We're talking pistol rounds, right?

Next reloading session (this weekend), I'll shoot a photo...

perhaps a little more “crimp” isn’t a bad thing.

See Bret's excellent explanation, above, why more crimp IS a bad thing and actually results in less tension and more setback...

[PracticalRifleman]

We're talking pistol rounds, right?

Next reloading session (this weekend), I'll shoot a photo...





See Bret's excellent explanation, above, why more crimp IS a bad thing and actually results in less tension and more setback...

I’ve read it. And it sounds nice. Except that isn’t always the case.

For instance, I just pulled out some factory gold dots and found the first 0.004” of the case to be 0.001” smaller than the the rest of the case which the bullet rests before tapered sidewall restarts.




0.376” for the first 0.004” then the “taper” is 0.380”.

I guess Speer Gold Dots are creating “dangerous” situations.

Or perhaps 0.004” doesn’t damage a bullet.

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[Bimmer]

For instance, I just pulled out some factory gold dots and found the first 0.004” of the case to be 0.001” smaller than the the rest of the case which the bullet rests before tapered sidewall restarts.

0.376” for the first 0.004” then the “taper” is 0.380”.

I guess Speer Gold Dots are creating “dangerous” situations.

Or perhaps 0.004” doesn’t damage a bullet.

That's interesting...

2¢:

1. I'm not sure 0.004" is enough to matter (or even measure consistently).

I'd be interested to see a pulled bullet, and whether the jacket is marked by the mouth of the case. (I bet it's not.)


2. Speer is starting with cases that are sized waaay tight, and that's what's holding the bullet in position, not an extra 0.004" crimp...

Look closely, and you can see that the case is slightly hourglass shaped: Wider at the base, narrow in the middle, and then wider again around the bullet, where the bullet has stretched the case.

[vicious_cb]

That's interesting...

2¢:

1. I'm not sure 0.004" is enough to matter (or even measure consistently).

I'd be interested to see a pulled bullet, and whether the jacket is marked by the mouth of the case. (I bet it's not.)


2. Speer is starting with cases that are sized waaay tight, and that's what's holding the bullet in position, not an extra 0.004" crimp...

Look closely, and you can see that the case is slightly hourglass shaped: Wider at the base, narrow in the middle, and then wider again around the bullet, where the bullet has stretched the case.

They are crimped, look at these factory pull downs. Remember these are plated bullets, the jackets are thinner and softer. I load a ton of plated bullets and my station 4 crimp isnt deep enough to gouge the jacket like these but its plenty strong enough to take a couple of hard whacks from a kinetic puller.

Im guessing factory Gold Dots have an aggressive crimp to prevent catastrophic bullet set back esp when you can trust your average cop to re-chamber a bullet a dozen times...

[PracticalRifleman]

That's interesting...

2¢:

1. I'm not sure 0.004" is enough to matter (or even measure consistently).

I'd be interested to see a pulled bullet, and whether the jacket is marked by the mouth of the case. (I bet it's not.)


2. Speer is starting with cases that are sized waaay tight, and that's what's holding the bullet in position, not an extra 0.004" crimp...

Look closely, and you can see that the case is slightly hourglass shaped: Wider at the base, narrow in the middle, and then wider again around the bullet, where the bullet has stretched the case.

0.004” is quite easy to measure with even mediocre equipment. I can replicate this measurement consistently.

I’ve pulled them before, and you can certainly see a crimp line. It isn’t significant, but it’s certainly there.

Of course, cases are usually hourglass shaped to some extent, but the first few thousands at the case mouth is smaller than the rest of the top of the hourglass, which indicates intentional crimping...and it’s repeated with all the rounds I have on hand and is consistently around 0.003-0.004”.

I’m quite certain Speer is indeed crimping self-defense ammunition. I think I have some Federal around I could measure as well. If I recall, it also looks intentionally crimped.


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[Bret]

They are crimped, look at these factory pull downs. Remember these are plated bullets, the jackets are thinner and softer.

All those lines show is that too much taper crimp has been applied which resulted in the bullets being deformed. This does not equate to a better hold on the bullet versus the taper crimp die being turned down just enough to remove the bell.

Bottom line: If one relies on a taper crimp to help prevent bullet setback, then they're doing something wrong. Proper sizing and seating produces enough tension between the bullet and case to prevent setback.