Originally Posted by bedlam
Was looking for a way to measure the amount, rather than the type of crimp to apply.
You can measure the force required to pull a bullet from a loaded round by making a simple tool. Put a bullet puller in a board clamped to a work bench top. Make something to hold onto a shell holder (spare ram for a press?) with a bucket attached to fill with weights. Put a sized case with bullet seated and crimped in place in the bullet puller, slide the shell holder onto the case rim, then start putting stuff in the bucket. When the weight finally pulls the case off the bullet, weigh the bucket and its contents and record the weight. Do this several times to get an average and spread of force needed.
I've done this comparing crimped case mouths to uncrimped ones. Crimping rifle case mouths onto bullets tends to increase the force spread to get the bullet out; especially on bullets without cannelures. And crimping case mouths onto bullets without cannelures tends to unbalance them a little bit. That added variable tends to make ammo less accurate in proper tests.