Picture below shows how high my ears are after grinding.
Modify mag catch for unmodified Colt mags. I initially started at about .040″ which cleared but was having malfunctions when firing as I think the mags were moving and rubbing on the carrier. You can see i’m close to .100″ now. I think if I were to do it over, I would start testing around .060 – .080 now….but what I have now is working so I’ll leave it alone.
Removing more material from the mag catch required the feed ramps to be deepened on my Hahn mag block. I happen to be using an MGI lower and a 556 mag well with Hahn block that has always been a little small for this magwell which I remedied years ago by bolting the mag block in place.
Youtube video of this configuration running in full auto: https://www.youtube.com/watch?v=cmAdCXDTUgc