Thread: Case head separation imminent

Originally Posted by Padox

This is in a 270 running 52gr of win 760 so 1.5gr below max book load and it only seems to happen in the 1s I used magnum primers in the rest are fine so far I've had 2 sleeve in the chamber and prob 10 actually split the casing around that Grove line I was contemplating weather it was my load or my rifle I have been using the same load for prob the best part of 10yrs and the 1st time iv ever had an issue with it and the only dif was I had to use cci mag primers cos I couldn't get any Winchester large rifle

Greetings again,
From your description I assume that you are using 130 grain cup and core projectiles. Looking at the data your pressure is around 48,000 CUP. This is well above the 40,000 CUP or PSI (the two are very similar at this level) by which the case stretching and head separation occurs. Ball powders like 760 are harder to light than the extruded stick powders and the WLR primer is formulated for it. Consequently the WLR primer is often considered to be hotter than other non magnum primers. My old Speer No 9 manual from the 1970's lists the CCI 250 Magnum for use with their 130 grain projectile and 760 in the .270. I don't doubt the experience you have had but find it hard to blame the primer for case separations. That said if you can get the Winchester WLR primers they are likely to be the best match for 760 in your loads.
Regards Grandpamac.