My friends are tired of hearing me say this: The Sig 320 is not just another handgun. It is changing gun world in ways we are just beginning to understand and will fundamentally change My friends are tired of hearing me say this: The Sig 320 is not just another handgun. It is changing gun world in ways we are just beginning to understand and will fundamentally change the way we buy and modify guns forever.

The Army bought the Sig P320 as the Modular Handgun System. What provides the “Modular” feature of the the P320 is the Fire Control Group (FCG). According to ATF, which is the only opinion that matters, the serial numbered FCG is the gun. All the other pieces are just parts, transferable without regulation.

The open design architecture along with increasingly available home manufacturing capability will let hobbyists take control of their guns in ways not possible before. Not only changing size and caliber on a whim, but making functional and truly custom guns tailored to the individual shooter.

Photo courtesy of SigSauer.com

Sig sells caliber X-change kits with all the parts you see above in various calibers and frame sizes for about $400 mailed directly to your house, no FFL needed. I counted 11 models on the web site, there will be more. I expect X model performance up grades packages with red dot optics and competition trigger parts coming directly from Sig soon.