I was told it was only an ‘M’, but I see it as a possible highly stylized ‘TVM’.
Reasoning - Thinking it might be ‘TVM' as the 1st vertical line for the 'T' is somewhat right in the middle of the 'T' top crossbar.
TVM Outfits - I am aware of the 'TVM' as in TN Valley Manufacturing that Jack Garner operated, but I always saw his full name in script on barrels.
Perhaps it might be an ‘early’ TVM mark from that TVM firm from Natchez, TN, (Matt Avance et al)? But back to ~12-years ago or so, from a friend’s rifle, I've seen Matt sign his as ‘M’ and his full last name on his builds.
Thoughts?