Hello all. I'm Norm, and I'm going to be looking for information from more experienced hands with Sakos. At this point I have a Coltsman .308 and an L461 .222 Remington that I've had for some years, and have performed well. I recently bought a pre-owned (reportedly not used) A5xx single shot 6mm PPC that is apparently going to take some sorting out. I'll also post in the 6PPC forum. The factory heavy barrel is marked 6mm PPC USA, the action Sako 6PPC A5xx, which as I understand it should be a non-neck-turn chamber. Factory 6mm PPC cases are currently made of unbotanium, apparently, so I have Lapua 220 Russian cases hydraulically formed. Necks measure .269 OD as formed in RCBS full-length sizing die and neck expanded, .270 OD with a Barnes 68 gr. Match Burner bullet seated. Neither will fully chamber. Cases sized but NOT neck expanded with a neck OD of .260 will chamber easily. The indicator "ring" in the tapered portion of a partially neck sized case (using die-makers blue) appears to be .262. A case neck-turned to .265 will also not chamber. I thought I understood that the Sako chamber neck was a larger diameter than the "benchrest" .262-neck specification. Any enlightenment would be appreciated!