Home Forums Reloading Big Game Rifles Bullet Wobble - Lapua Brass

Hello - just curious as to what thoughts y'all might have on an issue I recently encountered.

I've loaded 300 Win. Mag. with the same RCBS dies for many years. I full length size everything, new brass or used. I've loaded 300 WM using Winchester brass, Norma brass, and I'm sure one or two others.

Recently, I received some new Lapua brass and put it through my same full-length sizing process before loading. I always roll a few loads on a flat table just to watch them spin true. In a couple of decades of loading who knows how many rounds for a dozen or more different cartridges, I've never had a bullet wobble during the roll, but in the case of this effort with Lapua brass, the first 5 cartridges I loaded had bullet wobble. The cases were straight, but the bullets were definitely seated at a cant. I stopped loading there.

I pulled out a piece of Norma brass in 300 WM and put it through the exact same process. I loaded a dummy round and the bullet sat perfectly. Thinking the Lapua brass might be a little longer and perhaps I was over-working the brass, I measured a few and compared it against the Normas I had. On average, the Lapua was actually slightly shorter than the Normas.

Any thoughts?

I don't know the relationship for the 300 mag, but in 308 Winchester the Lapua brass I've used has thicker neck walls than Norma. So one theory is the pushing/pulling of the expander ball is heavier with the Lapua and it's putting some of the necks out of kilter.

I have to ask, why are you FL sizing your brass??? Also, to expect brand new brass, of any manufacture, to be absolutely perfect, is wishful thinking. New brass gets a look over, and maybe some measuring, but I don't get too critical until after it's been fired at least a couple times. Also, size to your rifle's chamber. A belted mag is no different than any other cartridge as far as I'm concerned: Meaning, .002" shoulder bump on brass that has been fired, and then check runout ("wobble" in your words).

I appreciate the response.

I FLS all my brass for a couple of reasons. First and foremost, I load for others. One set of 300 Win. Mag. dies (for example) may produce loads for multiple rifles. I really don't know how brass was processed at any given factory, but even if a batch was already sized properly, hopefully all I am losing is some time running each through a die again.

Next - even when building loads for my own rifles, I've found that much of the time if I start with new brass, then neck size only for the reloads, my results are off. Maybe it's just a matter of tweaking the scope a little, but in my experiences the recipe did change and got tired of dealing with those inconsistencies. It was a little guessing game from one rifle to the next, but once I started full length sizing everything, every time, that problem went away.

I too believe that most components are likely not perfect. I've never experienced that bullet wobble, though. Very strange...

Thank you.

Interesting insight, Mathman. I appreciate it.