Well - coincidentally, I just bought a couple of barrels from NSS. I spoke to James, the sales guy, who was very helpful and knowledgeable, and I asked him what the "Match" chamber was for the .243 AI in their Criterion Barrel, since that was one of the barrels on my shopping list. He told me that the only difference between the standard SAAMI chamber and the Match chamber is a longer throat for the longer, heavier bullets. It has nothing to do with turning necks. Just passing info on from what I heard from the horse's mouth.
As far as using once fired brass - I have used plenty, mostly 223/556 and 308 Win (I only use once fired, mixed head stamp brass for plinking, not for big game or the occasional friendly competition shoot) I clean it, inspect it, size it, trim it and shoot it without any trouble. Sizing the brass brings it back to a SAAMI spec, so it should fit in any SAAMI chamber. One of the many advantages of reloading for me is that once I fire brass in my rifles, I can then (usually) get by with just neck sizing the brass, and thus the now once fired brass out of my rifle, has a nice tight fit in my chamber. I assume, that no matter the source of brass, most of the reloaders start by full length sizing their brass, then trimming it to length. Therefor, in my mind - and in my experience, using quality once fired brass shouldn't be an issue. Just don't skip that inspection step and weed out any cases that are too beat up.