The SIG Sauer M17 is a full-size, striker-fired 9mm pistol built on the P320 platform with a Romeo-M17 red dot optic installed from the factory. It has a 4.7-inch barrel, SIGLITE night sights, and ships with 17-round steel magazines. The grip uses SIG's modular polymer X-Grip module. 
 

Key Specifications 

• Brand: SIG Sauer 
• Model: M17 
• Caliber: 9mm 
• Action: Semi Auto 
• Capacity: 17+1 
• Barrel Length: 4.7" 
• Sights: SIGLITE Night Sights 
• Optic: Romeo-M17 (pre-installed) 
• Grip: Modular Polymer X-Grip 
   

Detailed Features 

• The Romeo-M17 red dot comes mounted from the factory, so no separate optic purchase or mounting is needed. 
• SIGLITE night sights back up the dot for low-light target acquisition. 
• Two 17-round steel magazines are included for 17+1 capacity. 
• The X-Grip module is swappable for different hand sizes without touching the pistol's serialized frame. 
• The pistol is built on SIG's full-size striker-fired frame for a duty-style package.

Owners of the M17 generally rate reliability high, since it shares its internals with the P320 platform that has a long service record with military and law enforcement buyers. The factory Romeo-M17 optic gets mixed reviews: some like having a dot ready to go out of the box, while others plan to swap it for a different footprint once they have run it for a while.

Ergonomically, the modular X-Grip is well liked because it lets shooters resize the grip circumference without sending the pistol back for fitting. The SIGLITE night sights are a common praise point for anyone who carries or uses the pistol after dark, since they give a usable backup to the dot.

On value, buyers see the M17 package as a good deal because it bundles an optic, night sights, and extra magazines instead of charging separately for each. Aftermarket support for the P320 family is broad, so parts and holsters are easy to find once the pistol is in hand.