Re: 25-06 case head seperation?
Assuming your not exceeding manual guidelines, my first reaction is youre oversizing the brass each time, this will undoubtedly shorten case life, more then normal. FL sizing each time I will say that your case life wont be too good. (typically minimally sizing cases to fit your rifle’s chamber is what most do for bolt actions, for accuracy and case life).. If you have no choice but to FL size, make sure you know your max headspace dimension fo ryour rifle, so that you can minimize how much your sizing cases – another way that comes to mind is to get a body die, and a separate neck die, it may be easier to manipulate the case sizing with that setup. (bump shoulder no more then 2 thou.)
Next thing, if youre oversizing (during FL szg), chances are good you have too much headspace,.. this can and will contribute to case head separation.
Also, I would dbl check your break open action for any possible loosening, this may be a factor.
Next thing, if your seating bullets too far to the lands, this will cause pressure spikes, hence busted cases. If you know your rifle’s chamber dimensions (and case dims before and after firings), this would go a long way in understanding what the problem is.
Next, if you scratched your chamber, maybe a problem, may not be.. if it is a good gouge it could be a problem for your brass, otherwise it maybe possible to sand it out .
What loads are you using? Are you trimming cases every 2/3 reloads? When you say 5th, 6th rounds cracked, etc. , are you talking about “5th reload” or just 5th round fired that day?