Leadeye you have some of the coolest toys. I was impressed with what you brought to the shoot south of Martinsville back in May. In reality I've only had that M10 for a short time. It was NIB but came with the wrong mag.
What caliber? The 45s take grease gun mags with a slight mod. The 9mm works with a Walther MPL mag, which were easier to find back in the 70s , but I would bet they are still around.