Here is an SRC MP40, it comes with X1 high cap and X4 mid caps.

I got this gun in a trade a long time ago and it's never been used by me as I already have one.

I'm not a tech, so I'd advise a service so you have piece of mind as it's been sat unused by me for two years now but it seems to cycle fine when a battery is installed. It has EBB function which works.

These SRC models are steel and are much nicer externally than the AGM model and doesn't have the semi automatic function, it's full auto just like the real world gun!

The only issue I can find is one of the mid caps is missing the base plate but this doesn't effect the magazine itself.