Thanks one and all for your input one would imagine with SMG's like the Owen, Thompson and the Grease gun that having more in the mag is better insurance that say 25+- rounds.

No better place to test it than in the field but one would want 100% reliability before going out.
One thing with the Owen it could fire even after being immersed in mud literally there was some footage of it being tested and I think it may have been the great man himself dunk the thing in a mud pool pull it out and then rip off a full mag.