[lutach]

The Neu 1521 is 3.3" long (84mm) and the Mega 22/50 is 3.2" long (82mm) and if the 1521 doesn't fit, I think the 22/50 won't fit as well. I think the 22/45 will do the job well, the same length as the Neu 1515, but the 22/45 is cheaper.