I've been working on loads for a new M70 375 HH and am experiencing some issues. All primers are flattening regardless of powder charge - sounds like the shoulders are pushed back a little far. Next, fired case length to the datum point is .012" longer than the new brass measurement - sounds like excessive case stretching. Thirdly, fired cases are showing the frosty ring above the web - sounds like excessive case stretching as well. My problem is all loads have been fired with new, never sized brass. Does this sound like a minimum size brass issue or a maximum size chamber issue or combination of both? What are them SAAMI specs on the 375 HH? I could always throw more money at the problem and just buy a different batch of brass but I'd like to understand what is going on first. Thanks
