Mag fitting question..locks in..hard to get out

Well I helped a friend put together a Romy on a Nodak receiver today. After riveting the trigger guard and front trunion the mags were very tight front to rear and would not seat. I took a little off the front of the selector stop plate and the mags go in and lock up.

Problem is that it is all but impossible to push the mag release by hand. It is so tight a fit you have to hit it with something to release the mag. Where do I trim to correct this? It seems like shaving the top of the mag release might solve it but I don't want to mess anything up by grinding where I don't need to.

Where do I need to start ?

Look very carefully at the lock up and do this for a number of magazines from different countries. Make sure that the magazine is fully sitting front to back. If it isn't then you may need to dremel a bit more off the selector stop end of the magwell.

Make sure the receiver bottom didn't get bent in/out during your installation of the TG rivets. If it did, use a piece of wood and a mallet to apply an attitude adjustment to get the receiver bottom all flat and back in line. Test the mags again.

Now, if front to back is okay, and the bottom of the receiver is flat, look carefully at the mag catch. Do they all lock up hard? If so, maybe sand a bit off the mag release but go very, very slow. Don't take off any more than you absolutely need to.

That would be my three step plan. Again, test with multiple mags. For example, I have Hungarian, Romanian and Bulgarian mags to test with. Probably 4-6 different styles all in all.

If it's an NDS-3 receiver look at the rear edge of the magwell. If front of the mag catch / trigger guard / selector stop plate. If the receiver sheel extends forward towards the magazine it may need to be trimmed back a bit.

All the above is good advice.
I would add that IF your bolt rails have the magazine stabilizer bends on the bottom of them to make sure that it's not binding there. You may want to coat the mags with something that would give you some witness marks as to what area is binding. Red chalk dust from a chalk box comes to mind as a possibility.

i had a tight mag one all i did to cure it of the prob was to file a shallow "U"on the selector stop plate at the rear of the magwell... go slow and check fit till it locks in and pops off for you. don't overkill either! ur just filing to fit.

note:a dremel cone shaped grinding stone worked the best, but a round bastard file also worked.

Forgot to say why you must test with multiple mags - there is a lot of variation in the location of the magazine lockup tab, the thickness of the tab, the magazine's dimensions, etc. This can cause one magazine or even one type of magazine to fit very tight, or not at all, while others fit just fine. Thus, be sure to test and do your fitting use a number of different magazines if at all possible.