My 27” 280AI is doing 2950fps with 180VLDs and N560. Anymore than that is hard on the brass. I got lesser results with RL-23 which I had hoped to use. I think N550 might actually be better. Normal free bore I assume. Borrowed the reamer from a friend, but as far as I know he just ordered the standard 280AI reamer that PT&G stocks.
Why does everyone think they need a twist tighter than 8” in a 7mm? Berger recommends a 9” for the 180 and 195. Since Lapua took them over, Berger has reduced their twist recommendations, and in my opinion they went too far on a few bullets, BUT, they recommend a 9”. An 8” is just fine. Run it through a calculator and you’ll see.