Problems with bumping back 260AI cases

Kinjo

Kinjo

CGN Regular
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Location
southern Ontario
I've been load for my 260AI for a couple of yrs and I'm not new to reloading. I just started loading for my buddy's 260AI. Fire formed the brass and didn't resize them just necked them and loaded them again. After finding the load and jump I decided to body size them at the same time bump the shoulders back and then size the necks in a bushing die.
Put the first case in the die and walk it down to find the right setting, all is good. The next case required the die to seat a little lower. But the next two I couldn't get the shoulders to bump back at all. I tried walking the die in more to the point I was putting to much stress on the die, at that point I decided to quit.
Thought maybe annealing may help but these have only been fired twice. What am I missing? Has anyone else run into this problem?

Thanks
 
I would guess the brass is of different sizes, "dimensions". So the brass may have been fired with different loadings or you have mixed brands, Or brass fired different number of times, and brass of different lots can react different on the spring back after firing.
 
All Lapua brass and yes I did my load development with this brass. I figured it was the result of different charges but also figured I'd be able to set the shoulder back with the die set at the same depth as I use for my AI Lapua brass.
 
I've found it difficult to bump as well. I'm using Lapua .308 brass formed & turned which worked very well but chambering was a bit tight, so I decided I'd try a short bump and came away mildly disappointed. I've since annealed but haven't tried resizing those ones yet. I'll report my results in a few days.

Rooster
 
Chambers and reloading dies vary in diameter and headspace length. And you can't expect one bump setting good for one rifle to work with another.

Once in over 47 years of reloading did I need to lap the top of a shell holder to get a case to chamber. Far more dies will push the shoulder back more than necessary and why I use Redding competition shell holders.h

The problem is when full length resized the case shoulder is squeezed upward in the die making the case longer than the chamber.

You can try to lap the top of a shell holder for your buddies rifle a few thousandths. You can also try pausing 4 or 5 seconds at the top of the ram stroke when bumping the shoulder. This will reduce brass spring back and make the cases a more uniform headspace length.

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