How do know if the crimp is tight enough?

[Keiger]

Loading cast for the first time in 45acp. I tried running the calipers from the bottom of the case to the top, but the calipers stop right at the top of the case where the is still part of the belling.
Should the calipers be able to go all the way of the case if the crimp is right?

 

[918v]

Don't use calipers. Use your eyes. Hold the case up against the light to check if the bell is gone from the case mouth. You want perfectly straight case walls, and then a slight taper at the very edge of the case mouth. That's it.

 

[MachIVshooter]

Perfecting taper crimp is more by feel than visual. What kind of press are you using? I run on an RCBS single stage, and find that a good crimp is when the lever offers about half the resistance it does for resizing. I like a pretty firm crimp to ensure that bullet setback is a non-issue.

If it's rippling the case or squishing the bullet, it's too tight. If you feel no resistance on the handle, it's too loose.

 

[ChristopherG]

Turn up the crimp until the bell is gone. The case mouth should be about 0.471"

 

[Walkalong]

Neck tension does 99% of the job of holding the bullet still. The "crimp" is to remove the bell and help feeding problems from leftover belling.

The .45 ACP headspaces on the case mouth. All you want is to remove the bell and/or a hair more. Not nearly the pressure on the taper crimp die as the sizer.

I use magnification to check the crimp.

Sample pics
.

 

[ranger335v]

Walk is correct, a crimp is largely unimportant in pistol cartridges but removing the bell/flair is important. But, if your ammo feeds and chambers reliably you have removed all of the flare you need to remove.

 

[Dave P]

"a crimp is largely unimportant in pistol cartridges"

Not true for 357SIG.

 

[steve4102]

As already stated, in the 45ACP crimp just enough to remove the flare. The crimp is not there to secure the bullet, just make the case wall "straight".

 

[Walkalong]

Not true for 357SIG

Correct. Neither one of us was specific enough.

I posted:

Neck tension does 99% of the job of holding the bullet still

I'll add:

...in straight walled auto calibers such as the .45 ACP, .40 S&W, 9MM, etc.

In the .357 Sig it probably helps, but I haven't loaded .357 Sig and do not know. A good crimp can be very important in many revolver rounds, especially those with large charges of slow burning powder such as W-296 and heavy bullets.

 

[ranger335v]

Man, the .357 Sig isn't even on my radar as a valid hangun round!

But, why a crimp on even it is helpful escapes me. ??

 

[MachIVshooter]

A good crimp can be very important in many revolver rounds, especially those with large charges of slow burning powder such as W-296 and heavy bullets.

I'll second that. Back when I first started loading .454, I had bullets jumping crimp and binding the cylinder. Not fun to get undone.

 

[JimKirk]

A 357 SIG's neck is connected straight to it's axx, what little neck there is.

 

[Steve C]

For a straight wall case like the .45 ACP the belling must be removed to allow the round to chamber. With semi auto cartridges and lead or thin plated bullets crimping is seldom needed as these bullets are at least .001" greater in diameter than jacketed bullets and usually have sufficient tension in the case to prevent bullet setback when cycled through the action of a semi auto. The typical expander that comes standard in the die set is generally sized for jacketed bullets and is the part of the tool that determines inside case neck diameter.

For jacketed bullets some degree of crimp from light to heavy is usually needed to prevent bullet setback. The thickness of the case generally determines how tight the bullet fits. Using just thumb pressure, push the nose of your loaded round against the edge of your loading bench. If enough crimp is applied the bullet should hold tight and there should be no set back. If you get set back, increase your crimp by turning the die in a little and test again. Repeat until there is no bullet setback.

 

[Keiger]

I was following the instructions for the RCBS dyes and they said to turn down till you fill the dye hit the case then adjust by 1/8th turn to get the crimp you need. I had turned it 2 full turn untill I noticed the bell was going away. I think I have got it right now. I can now see where the brass is being tapered against the bullet, with no buckling of the brass. Thanks Keig

 

[JimKirk]

You must not have had the crimper touching the case if you turned the DIE down by 2 full turns. The brass(bell) may have been rubbing the sides of the die, but it did not take two full turns to get it to crimp. You may have some ultra fine thread dies, but most are 7/8" x 14 threads per inch.

1/8 turns are the right amount after touching.

Jimmy K

 

[Keiger]

I bet your right Jim, didn't think of that.
I put the case in after it was full of powder (Dillon press) and the belling gets done at the powder station. You just gave me that "Light bulb" moment.

Note to self: Dillon press users must put un-powdered brass in seating station to set die at initial height for crimping, then powder, then bullet in to seating/crimping.

 

[Walkalong]

Sounds like too much belling going on if it took 2 full turns after contact. You just need enough to keep from shaving lead etc, no more. You can bell more, but it will only wear out the brass sooner.