Mike;
I don't believe there is any more fire hazard with a ML'r than a BL'r unless one tries to improvise the wadding with something such as newspaper or the like. Do a goggle search on V Starr & I believe you can find his little book in downloadable PDF format. It is noted he wadded with two of the overpowder card wads (.125"-.135" thk) only with no fiber or felt & then used the same heavy card as an overshot wad.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra