Thread: Crimping and it's effect on accuracy.

I have never noticed any difference with crimping high pressure cartridges (.308, .270, .30/06 etc). I have read about the potential of crimping, negative and positive, but never observed any difference myself in my experiments. I usually end up seating my bullets just touching the lands or just off, and I theorise that seating the bullet this way would over power any kind of mild effect crimping would have.

The only noticeable difference with crimping I have observed is with lower pressure pistol-type cartridges like the .44 magnum and .44-40 WCF, or the old .45-70. In these cases the higher pressure of a good crimp gives a more complete burn on certain powders (AR2205 and AR2207)
(The exception is black powder in the .44WCF and .44-70, in which crimping seems to have no effect, in fact you can slip-fit the bullet and it gets the same velocity.)

So I don't bother with crimping except for these last cartridges, for which it is mandatory.