There are two different 4013s, the single stack version that is based on the 4513, and the double stack version simular to the 6906. The double stack version will take 4006 mags. When using the extented mags, you can also use a mag sleeve to get a longer grip.
Hi Smith10,
I believe I bought a 4013 with a dbl stack
mag but now I'm not sure.
I'll have to call my local dealer to confirm.
Last weekend when I was picking up my SIG P220
Stainless .45acp, my local dealer pulled-out the
S&W 4013 which looked mint and said, 'Would you
like me to hold this for you?', and I replied
sure!
But due to the excitement of picking-up my P220 Stainless with a
tactical rail and Drosing a P220 Combat in November....
I don't recall now if the S&W 4013 was a single or dbl stack.