I have just acquired an Interarms Mark X with a from my local gun shop and when I checked the head space it was off. My gunsmith told me it was an improved chamber. I have never fooled with improved chambers before so any advise would be great. I have ordered the correct dies so My main question is on fire forming the brass. The Win brass around here is $33 per 50 that I then have to load and fire form if im correct. Walmart has Winchester 30/06 for 20 a box. Am I able to just buy 5 boxes of that and shoot it for my brass or would the full power ammo be unsafe? I have a bunch of h4350 and Varget and about 500 rds of hdy 168 bthp. Do you have any good loads for these? Thank you for any advise.