44 mag question concerning the kinetic therory of bullets backing out

[FullCry]

I shot my 44mag today. I shot four rounds then measured the COL on the remaining two and they were .015 thousandths longer than their original length of 1.600. I shot five the next time and the last round was .015 longer than it was originally. Is .015 worth worrying about or should I jack my crimper down some more? I measured all of these bullets before and after. Thanks for any replies, FullCry

[kraigwy]

I dont want my bullets moving at all, it effects accuracy at the best, jams the cylender at the worse.

Keep crimping until the bullet stops moving.

[Lost Sheep]

I would not increase the crimp until I checked to see exactly where the crimp is gripping the bullet. Clean off the lube (are they lead or jacketed? I am assuming lead), load it and see where in the crimping groove the crimp is seated. It could be that the bullets are moving .015" to where the groove seats up against the crimp and after that, they will move no further. In that case, just back off the bullet seating to 1.615" and test those rounds.

Crimping works the metal and shortens your brass life (it gets brittle at the case mouth, which leads to cracks). If that amount of crimping is necessary to keep your bullets anchored in place, it's worth it. If that much crimp is not necessary for bullet retention (and proper ignition and burn) you are overcrimping and wasting your brass. Better too much crimp than too little, but optimal is just enough.

You will probably always get a tiny bit of movement. After the initial "slack" is taken up, there should be no more. The initial movement should not concern you if additional recoiling does not continue to lengthen the cartridges.

Put concisely, make the crimp and the crimping groove a close fit before making them a tight fit.

Good luck.

Lost Sheep

[SL1]

+1 on what Lost Sheep posted.

The first thing I would do is test the theory that COL growth stops at 0.015". Try putting 6 measured cartidges in your revolver, firing one, and remeasuring the remaining 5 for COL again. Then, reinsert those 5 and a new sixth and fire the new one. Then remeasure the COL on the first 5 again. Repeat until NONE of the 5 show additional growth, OR one gets too long to accept. This will give you a decent sample size of what your individual cartridges are doing under recoil.

IF they are stopping at 0.015" total COL growth, then you can probably adjust the bullet seating depth to start them CLOSER to where they will eventually stop "growing." But, you probably won't be able to get that last 0.001"-to-.003" of growth out of them.

You don't want to try to turn the case mouth inward farther than it goes without bottoming in the groove. You just want to make it roll over the back part of the crimp groove, rather than hang into the middle of the groove and not touch the back of the groove until the bullet moves forward.

That should be sufficient UNLESS you are shooting near-nuclear loads with heavy bullets. (You didn't mention your load.) There is a "step-down crimp" that Speer publishes for such loads in the newer near-nuclear cartridges like the .500 S&W Magnum, but they use specially designed crimping grooves on their jacketed bullets for that technique.

SL1

[Rifleman1776]

Crimp properly at the right point. Crimp tighter.

[sc928porsche]

Yes, heavy crimping work hardens the brass. The cure? Anneal! Its an easy process and really extends the life of your brass. Just be sure to anneal only the upper portion of the case and not the whole case. I dont loose many cases now that I started doing it. I use a "neucular" in my 44 with a heavy crimp and case life is now over 20 compared to 4-6.

[FullCry]

I'm using Berry 240 gr. HP bullets if this helps any and I'm using a Lee four hole turret press with the factory crimper. Thanks for the help everybody and if this info leads to anymore I would appreciate it. FullCry