Good to hear about the 21 round mags. I never thought to try it.
Here is a link to a thread I started about these: http://sigtalk.com/p250-p320-modular-pistols/153842-new-x-grip-adapter.html
Here is a link to a thread I started about these: http://sigtalk.com/p250-p320-modular-pistols/153842-new-x-grip-adapter.html