AR15.Com Archives
 Sigma, SD, and M&P mags, interchangeable?
CA_TX-Cop  [Life Member]
6/28/2011 2:28:39 PM
Hey,

just wondering, since S&W 1st, 2nd, and 3rd gen mags in the old autos were all interchangeable, are the 9 and 40 mags in the Sigma, SD, and M&P series interchangeable?

And if not, are they partially usable? Like the SD and Sigma work in each other, but not the M&P, or the SD and M&P work but not the Sigma?

Thanks in advance, couldn't find it anywhere.
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RabidMonkeyPox  [Member]
6/28/2011 2:40:55 PM
Nope, cannot do it
1IV  [Team Member]
6/28/2011 2:53:48 PM
No model cross over.
CA_TX-Cop  [Life Member]
6/28/2011 2:54:01 PM
So all three are completely individual?

Whose idea was THAT?

RedFalconBill  [Team Member]
6/28/2011 3:06:30 PM
Sigma - Yes
SD - Yes
M&P - Nope

The only thing different between the Sigma and the SD magazines is the floorplate and the shape of the followers.
CA_TX-Cop  [Life Member]
6/28/2011 4:54:00 PM
So the Sigma mags and the SD mags WILL interchange? They just look funky? Like using a S&W 59 mag in a Daewoo? Or a 17 mag in a 19?

RedFalconBill  [Team Member]
6/28/2011 5:30:39 PM

Originally Posted By CA_TX-Cop:
So the Sigma mags and the SD mags WILL interchange? They just look funky? Like using a S&W 59 mag in a Daewoo? Or a 17 mag in a 19?


The Sigma floorplate is thicker and will look a bit weird sticking out of the SD, but they work. You can order floorplates and swap out the Sigma for the SD.

The magazine body is the same length.
America-first  [Team Member]
6/28/2011 6:26:07 PM
There is not even one single part that can be shared between the M&P and Sigma.
sed6  [Team Member]
6/28/2011 11:48:31 PM
INTSB (in before the Sigma bashing)

Originally Posted By America-first:
There is not even one single part that can be shared between the M&P and Sigma.

And, I believe the fired brass envelope you get with the gun is the same for both.

Backon4  [Member]
6/29/2011 9:27:53 PM
Actually sigma and SD mags will work in a compact M&P. I have done this with my 40c for fun and it functions and fires fine. Just can't use the xgrip on them.
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