4.3 and 5.1 magazine part compatibility?
 

So I stripped my inlet valve threads testing some of my HPA taps on my 4.3 TM mag, so I'm wondering if I get a replacement base for it, will the 5.1 fit or does it have to be a 4.3 base?

Either will fit, just have to have the right length screw. The only difference is longer baseplates add BB capacity.