Too much roll crimp?

[Kayser]

Never roll crimped before. Using Lee factory crimp dies. Tried one at a half turn ("light crimp" according to the manual), and one at full turn ("heavy crimp"). The light looks way too light, and the heavy, well....it looks REAL heavy. You can see where it actually flattened part of the brass in the cannelure.




Safe to assume the heavy one is way over the top and unusable? Looks like something in the middle is the way to go. Are all roll crimp dies this sensitive (the difference between a half turn)?

[Kayser]

A sample of the rounds, post adjustment (note mixed brass). Seems like these qualify as satisfactorily "heavy crimped".




Technical (dumb question) : Is a roll crimp to prevent the bullet from popping -out- due to recoil (ala revolver), or to prevent crushing inwards from slide movement (auto)? Or both? Does this crimp seem decent for a big auto like the Desert Eagle?

I will say this : 44 mag ammo is a heckuva lot prettier than .45 ACP

[Bullet94]

The crimp looks right in your second picture to me. The case neck tension is what holds the bullet in place. The crimp keeps the bullet from pulling out due to recoil and also helps to hold the bullet a little longer before movement which helps ignition when using slow powders. Most auto loaders don’t use a roll crimp, neck tension alone holds the bullet.

[jacobtowne]

Agree with Bullet94 about auto loads. Rimless cases are taper crimped, not roll crimped, since the cases headspace on the mouth.
That said, the crimp in the right case is too heavy if it's flattening the mouth. Back off a little.
JT

[BigJakeJ1s]

Not all rimless pistol cartridges headspace on the mouth. For example, bottleneck cartridges such as .30 lugar, .30 mauser, and 7.62 Tokarev headspace on the shoulder, and may therefore be roll crimped.

Just to keep us on our toes, some rimless bottleneck cartridges do headspace on the case mouth (.357 sig).

Andy

[dodgestdshift]

The crimps from the Lee Factory Crimp die on my 44 caliber loads look like your "heavy" crimp. They shoot fine and I noticed a slight improvement in velocity consistancy. It does seem to wear the brass slightly though. Back off your load and work up to your current load using the heavy crimp, and see how it shoots. It probably will hold the bullet longer before releasing it, this could cause higher pressure but in my case it seems to improve powder burn consistancy. Whatever crimp shoots best use that crimp.