My typical exposure is 1/250sec or faster so what i write is from memory so stand corrected.
I though M9-M9M and M240-M246 behave the same when trying to make long exposure, i.e. ISO limited with maximum exposure capped to 1 or 2 minutes (60 or 120 seconds) at minimum ISO, dropping to mere seconds as ISO is increased.
Only digital Leica that allows long exposure, up to 30 minutes plus B (bulb) is SL601. All Leica's share common drawback, in camera noise reduction for exposure over 1 second, this takes as long as original exposure.
Edit: Included B(bulb) for SL601.
Edited by mmradman, 14 February 2018 - 14:56.