Jerry, they are detachable, however, unlike the G/K.43, they were meant to be left on all the time except for disassembly. You would load two k98 stripper clips through the top of the breach and carry on your merry way. Here is a crude reproduction of the magazine I am looking for:
http://www.berghof1944.com/ger_gal_other/g41_mag.jpg