I've been told it will work but I have my doubts. Any experience with this?

I've only run a few magazines of 9mm through a couple of my guns using a Super magazine but they worked...

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Thanks. The mag is a Colt 38 super so that's good.

The feed lips may be slightly different depending on the brand but it is likely to work fine.

I’ve tried it and it mostly worked fine. Depends on the individual mag. Some work well all the time and some are a bit spotty. I’d confine the practice to the range and use proper mags only for daily carry.

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Everybody could shoot

I have 9s and Supers, but have not used the Super magazines to feed 9mm. Some shooters have reported it works just fine. Can't hurt to try it, but my concern is that inertia will allow the 9mm cartridge to move around a lot in the Super magazine. What position will the 9mm cartridge be in when it's time to feed into the barrel? I suspect feeding will be normal.......most of the time..

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NRA Life, COTEP 640

My experience is that feeding of 9mm from a .38 Super magazine is unreliable. That might not be true for for every .38 Super magazine and every 9mm cartridge. Something best determined by experimentation.

If you have 38 Super magazines that are reliable when feeding 9mm, that's great! There is a pretty good chance, though, that such a combination will not be reliable. Only one way to find out for certain and that is to try it.

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VCDL, GOA, NRA

My question to the original post is”why”? Factory Colt 38 super magazines are worth twice as much as Factory Colt 9mm magazines in the current market. Sell your 38super magazine and buy 9mm. The gun was designed to run reliably with a 9mm magazine why would you take the chance running something in it that it was not designed for?

Actually, it's the other way around. The Colt frame will accept any caliber magazine. It's the magazines that are designed for the frame. The only difference between the .38 Super and 9mm magazines is that the 9mm magazine has a standing rib on its rear wall. That rib affects how the shorter 9mm round feeds into the chamber. My experience is that using a .38 Super magazine for 9mm with FMJ bullets will result in at least one misfeed from a full magazine most times. Rounds with different bullets could be better or worse. But even some of my 9mm magazines will also produce misfeeds occasionally, one magazine in particular. I just don't use it. There are guys who can fiddle around with bending magazine lips to improve feeding reliability, but I am not one of them.