9mm & 40 S&W STI mags

[Teamsterjohn]

Has anyone ever used a 40 S&W 2011 STI mag with 9mm rounds. I looking to install 9mm barrel in my older STI/SV gun and remove the 40 that’s in there. 

[davsco]

well apparently i picked up a 40 round that i thought was the 38 super round i ejected after one stage and that didn't go so well for me on the next stage...

 

anyways, i'd guess that your 40 mags won't work with 9mm (otherwise they'd make 9/40 mags), but as it sounds like you have a few, no harm in testing them.

 

also, consider just moving to .40 minor.  i've shot atlanta arms 40 minor out of my sti edge and it is a soft shooter.  obviously you'll give up a little mag capacity vs 9mm.

[belus]

I just tried it in a Gen 1 STI .40 mag. The first few rounds look good and it didn't immediately go to a salt shaker after filling it up, even with a Gram's follower.

 

However feeding the rounds back out again I got regular nose dives and wouldn't trust them to run.

[caspian guy]

On 4/28/2022 at 8:52 AM, Teamsterjohn said:

Has anyone ever used a 40 S&W 2011 STI mag with 9mm rounds. I looking to install 9mm barrel in my older STI/SV gun and remove the 40 that’s in there. 

You could maybe try squeezing the sides of the mag in to reduce the the distance between ribs that control the stacking of rounds in the mag, tune the feed lips, and probably install mag spacers while you are at it. But I wouldn't recommend it if you have any choice.

[sharko]

I've mistakenly taken 40 mags to the range with 9 guns and they worked ok but I wouldn't take them to a match. Looking at them the crease in the top sides just goes up further on the 9's. 

[waktasz]

The feed lips are too far apart. You could modify the lips but I'm not sure what other dimensions are different.