[hihoslva]

Or so I hope, anyway.

Since I cannot find any S40 mags anywhere (so I can modify them for 12 rounds of 9mm), I have switched gears.

I just placed an order with CDNN for some mags, including an M9 hi-cap (will be "sacrificed") and an M40 10 rounder.

I'm 99% sure that if I take the butt plate off the M9 hi-cap and put it on the M40 mag, it's the same frigging thing as a regular S40 magazine.

Which I can then, of course, mod to hold 12 rounds of 9mm.......

The M9 hi-cap will not go to waste; the M40 butt plate will fit it (but will stick out of the gun just a tad), and it will be a fine hi-cap for the range. At least I'll still get some use out of it....

I did also order a second M9 hi-cap to keep as-is, as well as a second standard S9 mag.

Lots of work for 2 extra rounds in the S9, but I think it's a worthwhile experiment.

Will post results after I get my CDNN order.....

 

[Matches]

I concur with your hypothisis and am curious to hear (and see) your results.

Matches

 

[madecov]

Good luck

 

[Guest]

be sure to let us know. I too have a feeling it'd work but do'nt have anything in hand to actually compare. maybe others can chime in.

there's no reason for Steyr not to simple make S9 mags at 12rd, all they have to do is change geometry of feedlips and witness holes from S40.

 

[Guest]

actually the reason is that pistol was discontinued before the ban sunsetted.
economics is usually a good reason for a company

 

[hihoslva]

Aight, y'all. Got my mags today, and just as I suspected, this works perfectly!

I have NOT modified the feed lips of the 40 cal mag yet. All I did was switch baseplates.

Took the baseplate from an M9 hi-cap, slapped it on an M40 standard mag, and viola - I've got an S40 magazine.

Now I just have to tap the lips closed for 9mm, and I'll get 12 rounds in my S9.

The hi-cap M9 won't go to waste either; I put the M40 baseplate on it, and it is still a perfectly fine 14 rounder that sticks about 1/2" out of the bottom of the M9. Fine for the range.

I did also get one extra S9 mag, and one M9 hi-cap to leave as-is.

And CDNN sent me a cool fold-away knife for free! Nice little surprise to find in the box!

So yes fellas, this DOES work out if you feel like spending the bucks and winding up with one "extra long" M9 14 rounder.

 

[Guest]

Very Cool!

Did you figure out how to reliably close the feed lips yet? Dimensions and detailed techniques would be very helpful.

Thanks

Jeff

 

[TheNatureBoy]

Did you figure out how to reliably close the feed lips yet? Dimensions and detailed techniques would be very helpful.

It may not be the most accurate way of doing it, but I just wrapped mine in an old t-shirt and hit it hard with a hammer several times on each side. Worked great!

 

[Guest]

It may not be the most accurate way of doing it, but I just wrapped mine in an old t-shirt and hit it hard with a hammer several times on each side. Worked great!

Very wrestler-esque indeed! How did you know enough was enough? Did you mic it with Vernier calipers?

How many rounds so far and have you had any problems? The reason I would be attempting this would be to get 12-round carry mags for my S9, and they would need to be absolutely reliable.

Thanks!

Jeff

 

[TheNatureBoy]

How did you know enough was enough? Did you mic it with Vernier calipers? How many rounds so far and have you had any problems?

I just went slow -- a couple of hammer shots, then test and compare to my S9 mags. After that, I put it in the gun and ran 2-3 full magazines. Since then, I have probably ran 500 rounds through the magazine without a problem.

 

[hihoslva]

I just now finished closing the feed lips of the 40 cal mag.

I used the "caveman" method also. Wrapped the mag in a sock, and tapped with a hammer. Not the most preceise method, but it seems to have worked great!

I have not fired the gun yet, but I have hand-cycled 4 or 5 magfulls (12 rounds - woohoo) without a problem. Seems to feed perfectly.

I will update when I get a chance to shoot it up. But so far, I see no reason to doubt this mod's effectiveness & reliability.

As a side note - I started by barely tapping the mag, and the lips wouldn't budge. I had to smack it quite a bit harder than I expected. But I slowly ramped up the force so as not to overdo it.

 

[Wings]

Can someone measure the opening and post it? I hammered down one where it will hold my 2 dummy rounds (need to go buy real ammo tomorrow) but it seems like the back part is still fairly wide and the top round pops out pretty easily. That said I can put it in the gun and release the slide without any problem but I doubt thats much of an indicator.

 

[bigtaco]

width of .40 feedlips... .380"

width of 9mm feedlips... .340"

i crushed the feedlips on some sigma mags that wulf did up. they feed 9mm pretty reliably. 2fte in 100 or so. i think it's a spring/follower problem, not a feedlip thing.

good luck!!