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My PCC Setup: The SIG MPX


I’ll be the first to admit that when I first saw folks competing in 3 GUN NATION (3GN) events in the new Pistol Caliber Carbine division (or PCC as it’s more commonly known) I wasn’t impressed.  In 3GN, there are actually several PCC divisions including Unlimited PCC, Optics PCC, and Irons PCC.  In USPSA (who also started up their own PCC competitive division this year) it’s a single PCC division.  In either case shooting in a PCC division is pretty much cheating.  Most shooters are going to be able to shoot much faster and more accurately with a PCC rifle than with any kind of a pistol.  And because you can shoot a PCC round on nearly any target found on a 3GN stage, you will have few transitions.  But wait!  There’s more!  Have a long range stage at your club match?  PCC usually gets to shoot no further from the target than 100 yards.  Have a stage with a description that calls for an up range pistol start?  PCC is mandated to start facing down range (it’s hard not to muzzle people with a rifle while facing up range).

All these inherent advantages made me pretty prejudiced against PCC and those darn cheaters that shoot in the division…that is until I got the opportunity to shoot PCC when SIG SAUER sent me their MPX to test and evaluate in the pages of 3 GUN NATION magazine.  It was practically love at first trigger pull.  I ended buying the MCX that SIG sent me and have since shot in both 3GN and USPSA matches with some measure of success.  After my very first USPSA PCC match (which had 5 qualifier stages) I placed 4th in the match:


I also made the list of “Top 20” list in the USPSA PCC Division, B Class (14th):


Not bad for my first time.  At my second USPSA match in the PCC division the following weekend I managed 2nd place in the match:


In terms of the set up of my SIG MPX for competitive shooting, I’ve done very little to the rifle – it really doesn’t need much to make it “race ready.”  The first order of business was replacing the stock SIG MPX trigger with a Hiperfire 24e:


It’s a very interesting trigger design that’s quite different from all the other triggers I’ve tried.  It’s quite good and I like it nearly as well as I like my Elf 3-Gun trigger I have in my standard 3 Gun rifle.

The piston-driven MPX has amazingly little recoil as compared to a blow-back designed rifle – I don’t even feel a need to put a compensator on the barrel.  I’m using a SIG Romeo 4a red dot optic which has been functioning quite well for me – it’s quite a value considering SIG is offering a lifetime warranty on their optics.  The only other competition addition I’ve made is adding some Springer 10 round magazine extensions to the factory 30 round magazines.


So far I’ve not had any issues with the extensions, but I have read about some users (as well as users of the more expensive Terran Tactical Innovations 10 round magazine extensions for the MPX)  experiencing problems with the bolt not locking back on the last round.  Of course, rarely will you shoot a stage in USPSA or in 3 GUN NATION which will require more than 40 rounds, so it’s not a huge issue.  My MPX locks back fine on the last round using both of the above magazines, but I suspect the issue is related to using the stock magazine spring with the extension.

Here’s a photo of the finished product:fy7a4101-edit-edit-edit-edit


You’ll note that I’ve opted to keep the original SIG collapsable stock on the rifle.  It’s light weight and fits me quite well so here again I’ve not seen a need to make a change.  I did add an Aimpoint T2 Micro red dot optic, mounted on a LaRue Tactical LT751 absolute co-witness quick detach mount.  The reason why I chose this particular red dot and mount is that I could use it in conjunction with the Aimpoint 3X Magnifier.   In the USPSA and 3 Gun Nation matches in which I compete, 95% of the time I won’t need a magnified optic.  When a longer distance shot is needed, 3 Gun Nation rules stipulate that PCC division competitors will shoot no further than 150 yards in distance.  So it didn’t make sense to me to put a magnified scope on the MPX which would add weight and not be as fast as a red dot optic like the Aimpoint.  Instead, I chose the Aimpoint T2 which can co-witness with the iron sights, and with the Aimpoint 3x Magnifier, which also has a LaRue Tactical quick detach mount – I can snap it on the rifle in about 5 seconds.  Here’s a photo with the Aimpoint 3x Magnifier attached:


The SIG MPX is an exceptionally nice rifle and particularly well-suited for competition use.  Many PCC rifles available on the market start with a traditional AR-15 product design, and convert it to a pistol caliber carbine (typically 9mm).  There is of course a cost savings by not starting with a blank sheet of paper and basing a PCC design off of an existing product.  In my experience however, reliability suffers as a result.  There aren’t many PCC’s out there that run reliably.  The SIG MPX was built from the ground up to be a piston driven pistol caliber carbine rifle – it is flawless in function, fit, and finish.  The MPX is considerably more expensive than other available options with it’s $1918.00 retail price.  The Lancer manufactured translucent smoke magazines for the MPX are equally well-executed and similarly pricey ($50-$70.00 retail).  SIG sells a three-pack of the magazines which include a free mag pouch which is the best deal going until another manufacturer (like Magpul) begins producing magazines for the MPX:



So far I’ve picked up 10 of the 30 round magazines, and one 20 round magazine (for shooting under barriers prone in competition).

So far, I’ve had an incredible amount of fun shooting PCC in both USPSA and 3 GUN NATION – I think the platform has a bright future in both organizations and I plan on shooting with my MPX quite a bit next year.

About John B. Holbrook, II
John B. Holbrook, II is a freelance writer, photographer, and author of, as well as and *All text and images contained in this web site are the original work of the author, John B. Holbrook, II and are copyright protected. Use of any of the information or images without the permission of the author is prohibited.

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