how do i really know if i am crimping right?

[dancinzen]

i started crimping 9mm and 223, on the idea people told me it makes them more accurate cause of pressure build and that it has a less likely chance that the bullet will move in the brass. so i went the safe route and bought a lee 9mm taper crimp so i can also crimp lead, and a lee 223 factory crimp that i was told you can still use on non cannulated bullets ( hpbt match). so everything works, the bullets still shoot, but i mean, i really feel like i dont know if it is under crimped and its a pointless step i am taking, or if i am over crimping and ruining the brass and deforming the bullet... is there any sites, tutorials, books, people in san jose, anything that can show me a more detailed way of really knowing than the one or two brief videos on you tube...

thank you.

[XDRoX]

i started crimping 9mm and 223, on the idea people told me it makes them more accurate cause of pressure build and that it has a less likely chance that the bullet will move in the brass. so i went the safe route and bought a lee 9mm taper crimp so i can also crimp lead, and a lee 223 factory crimp that i was told you can still use on non cannulated bullets ( hpbt match). so everything works, the bullets still shoot, but i mean, i really feel like i dont know if it is under crimped and its a pointless step i am taking, or if i am over crimping and ruining the brass and deforming the bullet... is there any sites, tutorials, books, people in san jose, anything that can show me a more detailed way of really knowing than the one or two brief videos on you tube...

thank you.

You ask a difficult question. For 9mm you can try pulling the round after you finish it. If the bullet is marked then IMO you crimped too much. But I have heard from seasoned reloaders that a slight mark doesn't bother them. It does bother me.
With 9mm you can also measure the top of the case after you crimp. .377" - .378" is exactly where you want it.

With my Lee Dies it is impossible for me to get a 9mm to .377" without denting the bullet, so I only crimp to .378".
With my Dillon dies I can easily get my crimp to .377" without marking the bullet at all. The difference in the two brands is the Lee starts to roll the case in, where the Dillon does not.

I think I safe way to figure out crimp would be to tighten it down until you mark the bullet and then back off a little bit.

Hope this helps.

[dancinzen]

It really does help, these are the little things that I can start checking... Thank you.

[Revoman]

There was a thread floating around awhile ago that stated to crimp until you cannot push the bullet into the case by putting pressure on it.

Take an OAL measurement.
Put the round bullet-end down on a wooden surface, leaving the primer end up. Push with some force on the primer end with your thumb, it's probably best to do this with a dummy-load. (Most folks use the edge of a wooden bench instead of the top as it's a little easier to push.) I would guess that you are putting around 20-25 # of pressure on the round/bullet.
Re-measure to see if the bullet has been forced into the case.
If it has, then you need a little more crimp. You want to just stop the bullet from moving into the case and that should be the proper adjustment for that bullet and case.
It may take a few tries, but you should be able to get it right by that method.
Now, I suppose that it makes a difference if you do not use all of the same brass/headstamp manufacture. That's one reason that I don't mix headstamps it makes a difference in the seating operation.

YMMV.
Many would not agree with my headstamp stance though.

[joelogic]

AFAIK, crimping makes rounds less accurate. From reading online, match shooters dont crimp. Your results may vary of course.

For pistol I lightly crimp so that the round chambers.
For rifle I put a factory round in the press, raise arm, screw down die until it stops, lower arm, screw another half turn, tighten lock ring.

Side note, even without crimping I cant pull a bullet out with my fingers.

[RaymondMillbrae]

On pistol rounds (like Hornady XTP'S), the jacketing is thick and hard. A medium to light crimp should be fine.

On plated or cast bullets (Rainier Ballistic, Zero, etc...), you want a super light crimp. These bullets will deform easy and "keyhole" if crimped too much. (Tumble and not leave a clean circular hole on the target).

For semi-auto rifle rounds (AR15/AR10) you want to place a slight crimp. This will protect the bullet from getting seated deeper in the brass when jarred within the magazine.

For bolt-action precision rounds, the brass should have the proper headspace for the rifles chamber, so some shooters will not crimp at all. (Look at some high power shooters "home-rolled" rounds. They are placed in their boxes right-side up - NOT upside-down like pistol bullets - so that the uncrimped bullets will not sink any deeper into the brass). The pressures within the fired round will expand the brass and seal it to the rifles chamber, before shrinking down in size again. This is why you remove lube from finished bullets. (Rifle AND pistol).

Shoot with a purpose.

In Christ: Raymond

[joelogic]

I have also read that over time the bullet will actually fuse itself to the case. So some long distance shooters will seat longer until they are ready to shoot and then seat a little deeper to break the fuse.

[J-cat]

To check if you are taper crimping correctly, look at the round against a light background, like the sky. You want the case mouth to be straight against the bullet shank, and then just slightly bow inward. Taper crimping does not hold the bullet in place. The case tension does. Taper crimping removes the bell from the case mouth and promotes reliable, snag-free feeding from the magazine into the chamber.

[dancinzen]

Thank you guys, looks like I'm just gonna have to do so experimenting!

[shooting4life]

You can use a caliper and mesure the case at the crimp compared to the beneth the crimp. The crimp should be a few thousanths. Maybe alittle more if a magnum revolver round. I don't us any crimp on bolt action

[SirLoki]

Easiest way would be to buy a case gage and set enough crimp to be able to drop a finished cartridge in and out of the case Gage , look into the EGW case Gage for 9mm. If it drops in and out then you'll be fine, double check it against your own barrel also

[bohoki]

i dont crimp 223 my necks get tight enough during sizing to hold a bullet firmly and the inside of the neck gets good and clean during trimming


take a caliper reading tap the cartridge on a table a couple times and see if it moves any

9mm i think the crimp is in the seater and i don't have it do any excessive crimping just so it looks like a little hair width of brass is crimped

its hard to explain but it works for me

[SixPointEight]

This was always a question I had... with .223 I just guessed. Haven't started on .40 yet. But the information here seems helpful. I'll have to re-set my .223 crimp die.