There is only about 3mm of margin left on my 80mm lens after focusing at infinity. There must be something causing your lens to extend slightly more than "normal". My C330f has a slight interference problem with the cocking lever. When mounting a lens, except for the 180 and 250, the lever has to be depressed slightly to allow the lens body to seat properly. I have forgotten this on several occasions

I also found my previously owned (original owner) 180 to have apparently been reassembled incorrectly after a CLA. The last element in the taking lens was reversed. All is A-OK now.

I performed a focus test a long time ago on all my lenses and found them to be excellent. There have been discussions here indicating that, e.g., “The 180 is not sharp.” And the next, “My 180 is the sharpest”. Both APUGers were probably correct. I have found that the lenses for the C-series require good maintenance practice. I thought my 180 was un-good until I found oil (?) on an interior surface. Disassembly and cleaning corrected the problem. I also hear that the 55mm is not the sharpest. I won’t argue about it but only to state that mine is OK.

There are a lot of things affecting focus on the C-series. One major cause of problems is the ground glass mounting system. I have heard several complaints from clients after they replaced or modified their gg. As you have no apparent problems with your 180, I doubt that is a problem.

Good hunting and best wishes.