Once a year or so I spend a Sunday afternoon doing stuff for a guy who has a bit of a collection. Not the kind of work I normally would do but once in a while it's fun to step outside the box. A box having four sides to step out of, this is the side labeled "saw, hammer, torch, file to fit" and it's a fun side sometimes as a relief from the struggle for perfection never attained.
Left, a Sterling SMG magazine-- you can see how the mag catch notch is not terribly deep to start with. The next one was worse and had worn to the point where it would not stay in the gun. A little chunk of steel brazed in at about the right place and filed-in from there and the mag is good again. I guess these are a little hard to find and run at least $40 at the minimum and usually well over $50. This magazine, among all SMG mags, is said to be the very best, having a follower with rollers, like crude roller bearings. Other than the notch, they do seem very well made.
Third mag is from a PPSh41. If you don't know what that is, look it up, super iconic. Fourth is a PPSh41 mag doctored up to work in the Sterling. PPSh41 mags are like $13 because the Russians made enough of them that they could pile them 6' deep in Stalingrad.
Of course none of this work saved anyone a dime, he'd have been much better off to buy the most pristine, new-in-wrapper Sterling mags at the highest possible price. But we enjoy each others' company and I think for both of us it's not about the money, it's about playing with what could be done if there was no alternative. Whether or not microbrews are involved, I will neither confirm nor deny.
On top, an aftermarket Luger mag that was a total failure-- too narrow by quite a bit, the mag catch would not engage. Mag needed a little bumper-over-er and now it works! In 1911 mags I think the Mec-Gar are pretty OK, maybe not so much for the old P08.