CMMG upper too tight?

[Scarecrow]

I used to have a RRA upper that used to fit my 2 lowers perfectly, but recently I upgraded to a CMMG 13.7" upper with Krink brake and the thing will only fit my Dlask lower, and even then I have to force like a madman to get the pin in. For the Stag its like the holes dont line up. Is this normal? Sure don't need an accuwedge!

 

[USP]

Nothing a bandsaw couldnt fix....

 

[Scarecrow]

I was thinking a drill bit but I dont want to screw up my upper.

 

[NaOH]

Measure the length of the lug for the rear take down pin. I've found different lengths on my Oly Arms, Colt and DPMS. Not one was the same. It's probably bottoming out.