Hi Randal_G, The mag catch notchs you have pictured are most likely not the problem, as the top edge of the relief cut is all we are concerned with. The long sharp cornered one on the Mec-Gar is again an oversize catchall opening to fit the most out of tolerance magazine catch buttons. Where'as the Swiss mag notch is precisely tuned to the Swiss mag catch button and any issue with the curve will soon work themselves out by deforming the notch radius until it, the mag catch, fits fully. Lots of Luger mags show this deforming as the mags settle in after a rew hundred rounds are sent down. On most Luger magazines, if you have a soft jawed pliers, you can squish them on way to make them longer, or squash them another to make them short? It is because all original mags are made of soft formable steel, and not heat treated like the Mec-Gar. So, you are limited to what you can do with a Mec-Gar mag, unless you shim it as previously or try to swap out some mag catches until you see some improvement. One thing one of the members tried, and it worked for him, was to bend the top of the notch out on a Mec-Gar with good results, just looks bad...
Best to you, til......lat'r....GT
BTW A 6" digital calipher might be your best new investment...