GCBurner said:Almost all of my mags are GI surplus or Colt factory, and I haven't noticed any baseplate markings regarding length variations, though I'm not sure what to look for
I'm referring to Commercial Colts, which were beautiful in their fit and finish. There are no markings on the mags. Each 1911 produced went across a magazine fitting bench, where a lady sat all day fitting mags to them. She had bins of mags than varied in length by 8ths and 16ths of an inch. She would slide one into each gun in turn. If it fit, she would grab another out of the same bin and send the gun off with the two matched mags. If the mag did not fit, she would return it to the bin and reach for either a longer of shorter mag to match with the frame length.
If you look at the mags in your 1911, you'll see that there is usually a space between the bottom of the mag and the bottom of the frame. We've come to accept this as normal...it didn't use to be. Granted there needs to be enough play in the fit to ensure that the mag catch seats into it's notch, but it isn't anything close to what you'll see in current 1911s. 1911s built after the War, just use long enough mags to fit into any frame length and we just accept the gap.
The kind of fit I am talking about would be like when Rolls Royce used different directional threads on it's wheel lugs for each side of their cars, to optimize the torque applied to the lug nuts