Good for lefties - SIG SAUER Ambi Mag Catch Assy, M400, 516

This is the same part that comes on the MPX (and other SIG weapons). I'm retired military and a leftie. Wish this part had been on every rifle I'd ever been issued. Works great. You need to be somewhat more intentional about manually locking the bolt back (because of the proximity to the bolt catch lower tab) but that is an easy thing to do and is rarely (if ever) time critical like a mag change. I have a Troy mag-release also (solid piece of gear and works great, but I have to be more intentional with it to get a mag dropped in a hurry). I'll be purchasing a few more of these for some of my other rifles. -Hope this helps in decisions.