I have reservations about this one.
In the 5th photo, the mark below the hypothetical M-mark might, with some good will, be interpreted as a very worn example of the Liege "perron" mark.
In the next photo, the marks look as if they were formed from individual chisel strokes, not a single blow with a proper stamp. And the numbers appear to have a hand-scratched oriental look about them. The trigger is also very crude.
But the makers name on the barrel looks good.
Thought: maybe an original Belgian-made barrel that was "recycled "long before the word was invented.
Patrick