The P250 2Sum kit provides complete out-of-the-box versatility by offering all parts necessary to have either a full-sized P250, shown outfitted here with Sig Sauer’s STL-900L laser/light, or a sub-compact P250.

For the LE officer on a budget, cost is always a concern. For uniformed duty, a full-size gun is ideal. However, for undercover or off-duty use, a more concealable firearm is desirable. For those who purchase their own gear, this necessitates the purchase of two different firearms — or does it? Enter Sig Sauer’s P250-based 2Sum kit, which makes ingenious use of a single serialized chassis.

All polymer-framed pistols have an internal steel rail set up to mate with the slide. Sig Sauer decided to make that component the “firearm.” The serial number is machined onto the steel frame and a viewing window is placed in a corresponding area on the polymer frame of the P250. The genius behind the P250 design is that the entire action, trigger mechanism, slide rails/frame, and so on can be removed from one polymer frame and installed in another. No tools are necessary to make this change over.

To swap the action from one frame to another the shooter simply removes the slide just as they would for cleaning. The slide lock is then pushed from right to left and out of the frame. Lift up on the front of the internal steel frame and remove the action.

Installing the action in a new grip frame is a simple process. The rear of the steel action is placed into a notch inside the frame and the unit is rotated down. Take care to align the trigger into the triggerguard. Re-install the slide lock and replace the slide/barrel group for that particular frame size. After you have done this the first time it will take all of two minutes if you move slowly and meticulously.

Sig Sauer P250 pistols are available in 9mm, .357 SIG, .40 S&W, and .45 ACP.  Frame sizes are full, compact, and 
sub-compact. Different sight configurations and accessories are available.

Gun Details

The Sig Sauer P250 2Sum is a complete pistol kit, but they call it the “Modular Pistol System.” Contained in one box you have a full sized frame with matching slide/barrel group and a sub-compact frame with slide/barrel group. One serialized action is packaged with each kit. That’s the beauty of the system. The action is the firearm, all the rest are just parts. The frames are black polymer. Each steel slide is finished in Sig Sauer’s Nitron coating.

The 2Sum kit I had on hand to work with was chambered for 9mm. One magazine is included for each frame size. The full-sized 9mm magazine holds 17 rounds and the sub-compact holds 12. Barrel length for the full-sized model is 4.7 inches and the sub-compact is 3.6 inches.

The signature blue Sig Sauer plastic hardcase has velvet-padded cutouts for each of the two frame sizes. The obligatory cable-style gunlock is included as is a pistol manual. Inside the box you’ll find a flyer advertizing a 2Sum Accessory Kit. For a discount price you can purchase an additional magazine for each frame and an add-on Light/Laser combination.

When I first sat down at my desk with the 2Sum kit I spent a half an hour disassembling, swapping the action, and reassembling the pistols. I kept doing it until I could complete the swap from one to another in less than 60 seconds.

I did find that it took greater dexterity to swap from the full sized from to the sub-compact rather than the other way around.  If you rush, the recoil spring/guide on the sub-compact can shift out of place. Suffice it to say that swapping from one frame to another is quick and painless.

After I had mastered the frame swap I decided to try my hand at switching the magazine release from left to right. Following the instructions provided in the pistol manual I was able to switch the magazine release button from right hand set up to left hand in less than 5 minutes.

Both of the polymer frames have texturing on the grips, backstrap and frontstrap. Aside from the overall size, the main difference between the two frames is the fact that the full-sized model has an accessory rail while the sub-compact does not. Also, the triggerguard on the full-size model has an squared/hook design. The sub-compact is rounded or sloped.

Sights on both the large and sub-compact slides were SigLite night sights with Tritium inserts. The rear sights are drift adjustable for windage. At press time Sig Sauer has 2Sum kits listed in 9mm and .40 S&W.