This question may have been asked before, so I apologize in advance, but I have searched and cannot find an answer. I recently purchased what I was told was a 12 round magazine for a 4013TSW. When I received it, it looked familiar to me. To me, it looks identical to my 12 round magazine for my 6906 9mm . It has a black magazine follower, and no caliber markings on the magazine. My current 9 round 4013TSW magazine has a blue follower and is marked 40 S&W. The new magazine accepts the 40 S&W rounds with no problems. I haven't tried it on the range yet. Short story, did I get taken, or are the magazines interchangeable between weapons and calibers? This has me puzzled.

Dave

S&W 3rd gen dedicated 40 S&W mags have a dimple at the front of the mag body that mates to a corresponding relief cut inside the front of the frame mag well. If your mag doesn't have the dimple, it's a 9mm mag. Also, when loaded, do the cartridges match the capacity holes in the sides of the mag? IIRC, black followers are 9mm. S&W 3rd gen 40S&W standard full size mag capacity was always 11 rounds. Did you pay a premium price for the mag?

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Quis custodiet ipsos custodiet

It does sound like a 6900 mag. It will probably work for a range mag with .40s' but I wouldn't trust it for self defense. The feed lips should be a bit tighter (.020"?) at the rear for a 9 mag. All the compact 40 double stacks are marked 9rds with loading holes and had either yellow(early) or blue followers. Earlier 69-6900 mags just had three loading holes on them.

All the standard size magazines I have for my 4013TSW's are nine round, with blue followers. It is considered a compact, not full size frame. You can use the eleven round magazines from the full size 4006, if you don't mind the magazine extending out of the well a little bit. If that bothers you, you can get a different base plate that will fill the gap & be a little more comfortable to shoot. The S&W part number is 24212. I think Brownell's has them also. Hope this helps!

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Lounge Lizard Extraordinaire

Thanks to all for the replies. The magazine does not have the dimple on the front like my other 40 caliber magazine, so I truly now believe that this is a 9mm magazine. I paid $35 for it. It will not go to waste. Again, thanks everybody! Dave