A local gun shop has a new MPX with the 4.5" barrel and the SB retractable brace on it from the factory.  I would have bought it, but the price seemed way high at $1899.

I haven't seen any on Gunbroker yet.   Has anyone seen any in person?

MAP on the standard SBR is $1849 so the price you saw for the k version really isn't bad for how limited the k numbers were.

The shop wound up cutting me a deal in the MPX K, Aimpoint T2, and sights.  So I brought it home.

Just waiting on a Larue mount for the Aimpoint and then it will be complete.

I haven't seen any other K MPX models on Gunbroker other than the SBRs, so they have to be scarce.

Here is a picture of my MPX Pistol with SB Brace and the new MPX K with the Sig retractable brace that is similar but different than the SB brace.  

The Sig retractable brace has a round button to press to extend and retract the brace, whereas the SB retractable brace has a longer thin cylinder shape.   The mount is different as well, and has a very solid lockup.  

Since the newer Sig rifles don't come with sights, I added a set of Magpul Pro steel sights to the K model and they are very low profile.  

Once I get my Larue mount in tomorrow, it should be range ready.  

^^^Very nice.

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Bought mine 2 weeks ago. The day I brought it home I put on a 3 lug adaptor. Mbus pro's, Trijicon mro, and a larue trigger. I put on a moe k2 grip yesterday but didn't take a picture of it. Overall I like it. Grabbed mine off gun broker the weekend after they announced its release in psb form. Prior only the sbr's were 4.5 inch

Overall I'm happy. At 50 ft after a super quick sight in of just rough estimates. I was able to get decent 5 round groups on the first time shooting it.
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