Receiver won’t fit together

[RonLancs]

Hi all, 

 

So first things first. We’re talking Nuprol delta enforcer... Yea I know.. I get it now.. 

 

So anyway, I managed to break the part of the lower receiver that holds the retaining pin to connect it to the upper. So, I bought a new lower (Nuprol Delta Recon Bravo) From A2 supplies. I did order the Delta Enforcer Alpha as it’s all they had in but yea, they sent me the wrong lower but after inspecting and measuring the two lowers I had they appear to be identical. 
 

I refitted all the parts to the new receiver and threw the gear box in after wiring it to deans. The receivers won’t close. I’ve tried removing hop up and fake bolt/charging handle and the thing still won’t fit. Guys, so I can repair this pile of excrement and get it flogged off to my friend who is just starting out, any suggestions on how to remedy this as I can’t wait to move onto pastures new. 
 

Thanks in advance, 

 

Captain First Buyers Regret. 

[Steveocee]

Probably a few more better images needed dude.

[RonLancs]

Hey man, managed to sort it! The screw on top of gearbox was  loose and sticking out. Sorted, thank you. Whilst I’ve got you there. I’m having trouble with prowin and prommy purple. I’ve flat hopped with namazu firefly but having feeding issues due to prommy purple lips being inside the chamber thus failing the drop test. Which bucking would be better?