Hey. The problem in muscle ups for me is that i have an instinct that when i finish the explosive pull up i immediately releasing my arms and im falling with my elbows on the bar and from ther i can do the muscle ups(the straight bar dip) and i can do 9 like this but i cant to the muscle up like it should be done and even a one hand over muscle up i cant do and i can do 20+ pull ups and 25+straight bar dips so if someone was in my situation or even not i would be very happy to know i can change my form(i think its a problam with my hand rotationn but im not sure.
Try putting your thumb over and not under the bar. Also try to put your full hand over the bar instead of beside the bar( beside the bar is for pull-ups). If you put your hand over the bar, you won't have to rotate it later. This would work for starting to do muscle ups. Hope it helped, remember to be explosive and don't let go of the bar! Let's go!! BarBrothers ALL DAY EVERYDAY!!! Salute!!!