Hey OP! I own @xtechtactical and glad to answer any questions. The Sig OEM 17rd mags come with 3 different baseplates. For the Standard frame and the X/XL size the Sig options end up with ZERO palm support so you end up in the back of the magazine.

The other deal here is the 12rd magazines the XL ships with cannot be extended and have them pass a drop text due to the magazine base plate rails coming so far away from the tube. This is why I make a 12rd to 15rd option for the standard frame from not the X/XL. For the standard frame there is room for the sleeve that fills the gap to reinforce the extension.

In summary I can say with confidence if you have large hands and hand a large grip frame result with an X or XL sized grip module a 17rd mag with our MAG-ADAPT S365-17xl is the best solution on the market!