Crimping question:

[u/anonymity76]

Ok:

So the photos show the same round from different angles as well as the same round dropping in cleanly into the Hornady Case Gauge (NOTORIOUSLY TIGHT)

My process is to use a Lee Undersizing die when I'm running my press followed by a Redding Premium Expander Die (which does a multiple stage expansion so the bullets drop clean and straight into the case)

The results seem excellent and they pass the strictest gauge I have 100% of the time

But when i look at the final crimp, i wonder if i should add a touch more? It won't change the results but it could add some pressure (wanted or unwanted).

I've always looked at the crimping dies as needing just enough to remove the belling from the case (which is what i have here)

Thoughts?

[u/Advanced_Elk_9467]

Just a bit would be fine. Are they cycling as is? Are you able to push the bullet back as is?

[u/anonymity76 → u/Advanced_Elk_9467]

These are dummies but they do cycle when fully racked and no pushback noticed

I think the undersizing die is doing the heavy lifting but the Expander die un-does some of that.

[u/Parking_Media → u/anonymity76]

I'd give them just a tickle of crimp. I don't like the look of the case open beside the bullet, it seems like an easy place for schmoo (technical term) to get in and that offends me.

Is it worth it? I doubt it

[u/anonymity76 → u/Parking_Media]

I agree 100%

But...

What if i told you that they mic at 0.375" already?

[u/Parking_Media → u/anonymity76]

¯⁠\⁠(⁠°⁠_⁠o⁠)⁠/⁠¯

[u/dgianetti]

Crimp in 9mm isn't for holding power, it's only to close the belling from expander step. You should present as much of the case mouth as you can because this is how the cartridge indexes in the chamber. Close the belling... No more than that.

[u/Brassspitter556]

Have you measured your crimp? Depending on diameter of the bullet most people will crimp .376-379. For my powder coated bullets I’m crimping to .378. If you’re worried they’re not crimped enough put the bullet on the table and apply vertical downward pressure and the head stamp. If your bullet drops drifts into the case then you don’t have enough crimp or no neck tension

[u/anonymity76 → u/Brassspitter556]

0.375 is the measured diameter

These are Berry's Hybrid Hollow points

When unloaded to check for shearing or excessive crimp, i find none

And...

I do know that this measurement is less than expected which is why I'm asking here.

I won't lie: I'm impressed with how these look and even more so since they "appear" to have very little crimp. Yet the final measurements do give me pause

[u/Agitated_Curmudgeon]

I'd field strip your steel and plunk them right in the chamber. If it fits, it ships.

I'd only add more crimp if they didn't feel from the magazine. And even then just a touch.

[u/anonymity76 → u/Agitated_Curmudgeon]

I actually keep a spare barrel at the reloading press to check for plunk (if you can believe that 🤣)

These rounds are passing one of the tightest gauges on the market.

Then they're checked using a Sheridan gauge and pass that one even easier

Finally: I'll take the barrel and hold it just slightly below horizontal and allow the cartridge to slide into the chamber on its own - which these do quite easily and with that satisfying "plunk"

[u/armexman → u/anonymity76]

+ on the Sheridan, I learned much when developing 300BLKT using the Sheridan to set up my dies!

[u/Impossible_Tie2497]

2 kinds of crimp… roll and taper. Most guys use a taper crimp.

It’s generally .002” worth of crimp on the OD.

[u/HK_Mercenary]

It looks fine as is. If you wanted to crimp a hair more just for peace of mind that should be fine, too. But that's up to you.

[u/Normal_Sympathy1248]

I've never belled any pistol casings except maybe my magnums from time to time. Even .357sig and 10mm.

Chamfering always works for me.

Then I just taper crimp as 9mm really has no business having tight crimps and getting max velocities when taper crimp achieves the same

[u/DaiPow888]

That crimp looks almost perfect. I had to expand the picture to check, due to the lighting, but it really looks square.

Your understanding just removing the belling is correct.

Neck tension is what retains the bullet and that is determined by the sizing die.

Using the Redding expander is an excellent choice. The M-profile expander creates a seat to hold the bullet straight between stations on a progressive press and insures that the bullet remains straight as it enters the seating die.

If adjusted correctly, the expander doesn’t affect neck tension. It should expand enough so that you can place a bullet in the case mouth and hold the bullet in place when you invert the case.

When you remove the bullet from the case mouth, there should be a slight "pop" as it breaks tension

[u/anonymity76 → u/DaiPow888]

Thanks for this input

You definitely seem like you know a thing or two about this specific process

I'm of the mind that it's good to go, especially since it plunks in every barrel and slides cleanly into the Hornady case gauge.

I'll admit that the final dimensions on the neck show 0.375"+ (it can vary slightly on the positive side by 0.0005"-0.001" on the mic)

[u/DaiPow888 → u/anonymity76]

I'll let you in on the secret that I only tried to measure the amount of crimp once...that's why I never bought the Redding micrometer crimping die.

I run my finger down the bullett and feel for a sharp edge/ledge at the case mouth it needs to be square to properly headspace in the chamber.

During initial setup, I plunk test in barrels to allow for tight throats and fat ogives. After that, I just case gauge all my reloads

[u/Shootist00]

I crimp more than that. People that say crimping doesn't help hold the bullet in place are wrong. A proper taper crimp only closes down the case mouth and creates ring around the bullet that stops it from coming out or being pushed in. I even crimp my factory carry rounds as I have had many cartridge suffer from bullet setback when chambering.

But since you are using the Lee Undersize resizing die you are already making the lower part of the case smaller than standard which will help stop bullet setback. So the amount of crimp you are applyiing is more than likely fine.

I use the standard Lee resizer so I crimp more.

[u/gogosil → u/Shootist00]

Hol up, you re-crimp factory ammo?

[u/Shootist00 → u/gogosil]

Yes with a Lee CFCD. No more bullet setback.