1. The original magazines for the old Colt 1911's [WWI era] both commercial and military had lanyard loops. They were later discontinued in favour of the lanyard loop on the mainspring housing only. On my old 1911's I like to display them with the correct magazines. Those old lanyard mags are very collectible now, too.
2. That refinished 1944 USGI just has a standard 5" barrel. It's an optical illusion with the angle at which that second pic was taken that makes the slide look 'longer'. I have a Colt Series 70 National Match barrel in that pistol [and a full length guide rod]. Other than the action being very smooth it's pretty much still stock. It's really a "shooter" made to look like a cherry WWII vintage USGI 1911A-1. Anybody notice one more thing about it, that I have not mentioned, that is "not stock" on it? [check the pics....

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3. On the general question... I wouldn't hesitate to put rounds thru a WWII vintage GI pistol... like your Colt. I think it's the real old ones like the WWI era commercials and military's where I'd spare the shooting. Sure probably okay to put a mag down range occasionally but I wouldn't start banging hundreds of rounds thru 'em. The modern stuff, yeah I say pound away!