OzFclass

Hi there, any thoughts on causes of split necks in Lapua 308 brass.

Looking at cases for prep I have noticed some have splits to about half the neck height.

My thinking is that the load of 46.5gr of 2208 with a Berger 155.5 projectile with a 20 thou jump might be the cause.

I have gone back down to 46.0gr of 2208 and have not seen any more.

I have some 2206H powder that I am going to try as well, typically 1 grain less than 2208, which is supposed to burn cleaner

I had thought previously that it might have been that some cases had been trimmed for length and this was the cause.

I have 300 Lapua cases, all of which have been reloaded 5 times each.

Any info would be great

Ben

A warmish load, but not excessive to be sure. Still 1/2 grain more than I tried....

One other thing to look at is the fired vs resized neck diameter. Could you be overworking the necks ? And if so could you come up a thou or two in collet size and still have sufficient neck tension to hold the projectile ?

Andrew

Powder charge will not cause split necks. If the cases have been fired a number of times neck annealing may be in order. It is possible that this batch of brass is harder in the neck area than normal & annealing will correct this too. I have never had a split neck with quality brass. Years ago I would get split necks after several reloads with Winchester & Super cases in hunting rifles. I have never had a split neck loading for target rifle & F Class, I have regularly loaded ADI .308 cases up to 50 loadings with no sign of split necks, never annealed either. I have Lapua .308 cases I have loaded 30 times without splitting a neck. So I suggest it may be an odd batch of brass or you are somehow overworking the necks.
Keith h.

You could try annealing some cases and see if that helps,but at only a few reloads that doesn't seem necessary,I would clean my reloading dies well and give them a polish with something like Autosol.Could be worthwhile measuring the expansion of your cases on firing,as well as the amount of sizing from the fired state,then back to the expanded state before seating the new projectile.
The problem you have isn't usual,or at least something I have come across.

I have some photographs to further explain

What sizing dies are you using? What's the sides and loaded neck size?

Steve

Ben,

I remember waaaaay back in the late sixties, it wasn't an unusual practice to partial neck size cases using a standard FLS die - heck, they were all that was about. Then some smart guy found that cases lasted longer fully sized than the partially sized ones did. The notable point was that the necks split from the new junction point formed where the sizing finished, looking just like these pictured, whereas those full sized had a "natural" junction originally formed during manufacture.

Maybe this is relevant to your case.

John

looking at the top picture, it looks like the neck has expanded down to the bottom of the split, i would be doing some measurements on a few things

Ben, do some measurements with a vernier caliper and let us know the fired/unfired neck diameters in thou", the throat width if you know it from the barrel markings, the size of your neck collet, and maybe a picture of an unbroken resized round to see how far down the neck your die is adjusted. Lapua brass should not be doing that ....

Hi Ben

I use this brass too and never had a crack of any sorts
I anneal using my annealer every reloading
viewtopic.php?f=5&t=7047&hilit=annealer
Then bump 1-2 thou every load and neck size
It has served me very well with no signs of cracks in the neck.

I agree with everyone else and you may possible be over sizing the brass.
Annealing will help with this to a point but work harning the brass may case your issue

Just my 20c worth but good luck sorting it out

Peter