Occasional tumbling bullets...What's causing it

[Steve RA]

Take the FCD out and try the new one. The difference in case thickness is what is causing that.

[AzShooter]

The biggest problem causing tumbling is speed. Increase your powder charge .02 grains at a time and you will see the problem go away.

[BeerBaron]

A couple points. Yes the lee seat die is a combined seat + crimp die. Crimp is adjusted by the die body height relative to the shell plate and seating adjusted by the knob on top.

To stop it crimping wind out the seating die as far out as you can but still have it seat correctky with the knob nearly all the way down.

The fcd should be set touching the shell plate. This just sets it up to post size the case. Not the crimp. The crimp is set by turning the knob. Clockwise = more crimp. With coated lead you need basically no crimp. Just neck tension holding the bullet. Unfortunately some worn/thin cases may not have enough neck tension. That's just a fact using old brass.

The fcd just helps remove any rings/bumps. It is a taper crimp. Adjust the crimp just enough to remove the bell and any lip on the case. It shouldn't leave any ring.

I've had the lee 4 die set working perfectly in 9mm on my 650 with coated and plated.

[MilkMyDuds]

I must have screwed up at some point.

I replaced the FCD with a Redding taper crimp die last night. The Redding one worked flawlessly BTW. After some adjustments, it would remove just the flare without actually crimp. I measured 10 pulled bullets and all of them have the same diameter up or down after the crimp. Perfect.

I inspected the FCD. Shockingly I found a bullet inside the die... I took it out, then I found another bullet! This explains the couple occasions when I had empty primed brass and spilled powder in the bin but no bullets.

These 2 bullets measured 0.352 and 0.353 on the base and 0.356 on the middle.

So how did the FCD pull bullets out? Here is my theory. It all started when I started using the Dillon lanolin based case lube. I likely have used a bit too much, that combined with some unusual thick brass and various debris forming the grip, causing the carbide ring to undersize the ammo, eventually on the upstroke squeezing the bullets out of the case. I am at fault much more than the FCD is, because I have loaded over 10k rounds with FCD no problem, but the tumbling just started recently.

I am glad I found this. Many lessons learned:

1. Clean your dies periodically

2. Use Hornady one-shot for 9mm case lube

3. Get to know which headstamps have thicker brass walls (and better yet sort them, and use only the ones yielding the best results for your setup, especially for matches)

4. Try a taper crimp die that only removes the flare without actually crimping

Edited September 3, 2015 by MilkMyDuds