Guys just to give a few more details. I live in the southern part of Australia in the Victoria area known as Gippsland Not an area renowned for excessive hot days. On the day we were shooting the weather was overcast with a max temp for the day not much more than 75 degrees farenheit. As I mentioned earlier all these rounds were brand new in the box factory rounds not hand loads. I do not have any unfired cases here to measure the fired cases against otherwise I would do so.

I only have full length resized cases which have and are working fine in the rifle with my handloads pushing 340gr woodleighs at a chronagraphed average for 5 shots of 2550 fps and 400 gr frontier bullets at a chronagraphed average for 5 shots of 2385 fps.

Whilst I did fire a lot of rounds in a resonably short time - but not any shorter than what may be expected if I were doing a controlled animal cull- I only had the primers drop out of 3 cases from the one box of ammo.

I understand the theory behind how pressures can increase in hotter weather climate and ammo can be heated if left in the sun etc, but in this instance I was using a standard of the shelf rifle with standard of the shelf ammo on a day of mild but overcast weather aformulae which any normal person would expect to work. I concede that there may have been some barrel fouling at play here and that is my fault but would have thought in a big bore hunting rifle it wouldnt be a problem.

The fact that The ammo company is willing to replace the ammo leads me to beiieve this was a problem with quality control of the factory Ammo and not a problem from handloading, overheating barrels or excess sun.

Daryl you make some interesting points and it would be interesting to put a few different calibres through the strain gauge test.