just got a 4 inch Tactical Solutions threaded upper.

when i try to install it the mainspring housing moves into position correctly, but when i try to close it 
you can tell that its hitting something.  turns out the top latch part of the mainspring is hitting the base of the 
receiver frame.

i have been doing some searches on this and one persons said he had to bang on it.  i assume what he did was form
the aluminum on the receiver a bit.  the manual said this would void the warranty so im not hitting it with a hammer today

and its sunday so what say the hive 

edit: well i remembered i have a mark 1 from 1973 sure enough it fits on that frame...wtf

Did you get this worked out?

If not, pm me. I went through this too, but with a threaded ruger upper that the PO swapped with a TacSol.