The Sig Sauer P320-M18 caliber exchange kit in Coyote tan (brand part no. CALXM18CSSMS) converts an existing manual-safety 9mm P320 into the civilian version of the U.S. Marine Corps’ M18, the official sidearm of all branches of the U.S. military. Sig Sauer includes a carry-size 3.9-inch Coyote-tan PVD-coated stainless steel slide and barrel with recoil spring assembly, plus a Coyote-tan carry-length grip module. The SIG-LOC MHS footprint accepts a ROMEO-M17 red dot (sold separately), and SIGLITE front and removable rear night sights ship installed. The kit includes one 17-round magazine and two 21-round magazines. Among conversion kits for semi-auto handguns, this P320-M18 kit favors existing P320 owners who want the military-inspired M18 configuration.

Key Specifications

• The chambering is 9mm Luger, and the kit includes one 17-round and two 21-round magazines.
• The barrel measures 3.9 inches, in a carry-size configuration.
• The slide is Coyote-tan PVD-coated stainless steel.
• The footprint accepts a ROMEO-M17 red dot optic (not included).
• The sights are SIGLITE night sights, front and rear.

Frequently Asked Questions

What does this kit convert? An existing manual-safety 9mm Sig P320 into the civilian M18 configuration.

Is the ROMEO-M17 optic included? No, the slide accepts that optic, but it’s sold separately.

Buy the Sig Sauer P320-M18 Caliber Exchange Kit

A complete conversion to the military-inspired M18 configuration is exactly what this exchange kit delivers for existing P320 owners. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.