I been fire forming K Hornet brass using new Winchester brass, 45grain Winchester bullets and 296 powder. My problem is I been blowing out case on the side, near the base of the case.I was using 10 grains of powder and seating the bullet to touch the lands. I talked to the owner of a reloading store that I shop, and he's a small caliber wildcat guy, and he recommended PPU brass. We weighed a Winchester case and a PPU case and the PPU was about 10% heavier. He also recommended using Lil Gun instead of 296. I used 13 grains of Lil Gun and a 45 grain Sierra Hornet bullet today and loaded 5 Winchester and 10 PPU. This time I seated a little deeper hoping to lessen pressure. The Winchester made pretty little K-Hornet case with no signs of breakage or pressure but the PPU split the necks on 6 of the 10 cases. Do I need to anneal the PPU cases before fire forming? Or do I maybe need to back off the powder due to the thicker case? Kinda stumped here. What do you guys think?