Forgot my reading glasses and so shaved with the razor a half twist open. The Osage Rub says it was a smidge too aggressive but I had an easy, comfortable BBS shave - dialed it back a gnat's crotchet for the ATG pass on my (facial) tender parts.
There is not a locking mechanism nor a ratchet setting - the aggressiveness is infinitely variable, held by friction against a spring. I noticed that the setting may be changed by rough handling - drying the handle with a towel whilst holding the head in my case. A stronger spring might be considered if one is available in this size. I did not attempt to tighten the compression nut.
Short, fat handle aside, this is one superb razor, brilliantly designed and executed. I recommend watching out for them to come to market.
I'll polish, pack and post this one to Nico asap.