Bones,
The bore on my knight ultra lite is tight too. The 275 loaded tight but it shot great. It was not so tight I needed a hammer or anything. The ash from BH helps with that some after the first shot too. Sabotloader has a couple of the UL and he shoots a couple different 458s in the bloodline and Lehigh line up.
Bore diameters vary a lot from manufacture to manufacturer and even vary some within the same model. That's a Big reason a lot of us have 2or 3, or more, different sabot on hand to get the right fit.
I'm at work right now but let me look when I get home. I might have a couple of the 275s left in one box I could send you to see how they fit. I know I have a couple full boxes but I think I have a couple in an open box. I am sure you would need to use a short starter to get them past the crown, but that is a good thing in my book. Never know but they might fit great in yours. There was a couple reasons I changed over to the Lehigh, got was just one reason. But if Lehigh was not selling the CF, I would definitely stick with the blood line with no regrets. One thing I am sure of is that you will really like the bullet terminal performance. :yeah: