Canon LTM 50mm 1.2 - mounting query

[Jimbo035]

Specifically aimed at users of this lens . . .

I have a newly serviced one (serial number 546**) for my Canon 7, and when screwing it on to the camera it turns very smoothly and steadily until almost the very last turn, when a noticeable degree of resistance is suddenly felt and the final turns needs a little more effort. (No force necessary). There are no problems using it whatsoever...viz. smooth focussing over the full distance range, and it behaves exactly the same on a Leica lllf that I just bought.
Both cameras are in full working order, by the way.
The only other lens I have for both cameras is a 50mm Jupiter 8 which (to coin a phrase) screws all the way in unhesitatingly.

Are other users of this lens familiar with this characteristic? Is it in fact normal ?

 

[ruby.monkey]

Not with mine. It screws in smoothly all the way.

 

[Fixcinater]

I have had two of these and neither do as you describe. No answers but some questions that may help:

Do you see anything in the threads on the mount like corrosion or dinged threads?

Does it change if you focus away from infinity before screwing in the lens vs. keeping it locked at infinity?

(Maybe obvious...) Do you see any fresh scrub marks where it is rubbing?

Did it do this prior to the servicing or did you find it during inspection after receipt?