The C broad arrow was used until the early 1950’s, but not sure when the C should of service marking stoppped being used. Observationally, I would say the 1920’s some time, but that’s just based on the dates of observed rifles I have seen and when they were likely sold.
Many sniders would have been surplused before the C-arrow came into use. You sometimes see M&D marked sniders with British style opposing arrows, or no sale marks at all.