WE SMG8 MP7 with one working mag and 4 additional faulty mags
The faulty mags have varying issues, one leaks gas from top, 1 will gas out upon firing a few shots (but works if it’s warmed up), other 2 leak from the bottom. So, you could get a couple more working by switching bits around. Or all 4 by buying the valves (which would be around £20 to fix them all) 
Has some of the usual smg8 quirks (can read about these online) but generally works without an issue. 
Any questions just ask 

07946086235