Crimping & Goldilocks have a great deal in common... right up there with kissing a lot of frogs until finding the one(s) that's juuuust riiiiight.
But because eating all that porridge can get so tedious (and you already met a lot of frogs in high school), realize that things are fairly simple:
There are really only two types of crimp:
(1) one that smoothly "rolls
" the case mouth over and into the bullet; and
(2) one that "squeezes" the case mouth into the bullet in a taper
There are endless variations on these two themes, but that's about it in a nutshell.
Remember a couple of other things....
- Most rifle cartridges "need" no crimp. If you just have
to have a crimp, make sure you have a bullet manufactured w/ a crimping groove already in it. Otherwise you'll just make matters worse.
- Rifle cartridges in tubular/lever action magazines probably do
need to be crimped. Make sure you use bullets that don't
have an appreciable point, and that do
have that crimping groove mentioned above.
- If/when a crimp is used, rifles generally use roll crimps.
Pistol cartridges do need crimps when
- You have a heavy bullet in a heavy-recoiling revolver
. There the bullets tend to back out of the case under that recoil, and can actually interefere w/ cylinder rotation if not secured. Whether a crimp in actually required can be known in just a few shots. Revolvers generally take roll
crimps and the bullets need to have a crimping groove.
- You have an automatic
in which (a) the case mouth has been "belled" to seat the bullet and therefore requires straightening out to finish the reloading; and/or the case mouth is used to headspace the case in the chamber and whose diameter therefore needs to be precisely reshaped to feed correctly. In either case, automatics take tapered
SEATING & CRIMPING:
crimps can be perfomed simultaneously while seating if
the die is properly adjusted for proper no-crimp
; then the seater is backed out
and the die screwed in for proper [not
overly-gorilla'd] crimping; then the seater is screwed back in to contact the bullet while fully up in the die. The die is then set to both seat and crimp w/ one motion. Some people still prefer to crimp as the last step. (Only the frog process can teach you that.)
I find that taper
crimps on autos is best done as the last separate step.
`Just my opinion, but I got tired of frogs in my old age.
post script: Fewer frogs are required if one reads the die instructions.