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Maxim Defense PDX, M-RAX Rails, & Stock for the SIG SAUER MPX

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After we awarded Maxim Defense PDW Best of SHOT Show 2019, we had to take the time to visit with them at length during the Big 3 East Media Event to check out what they brought with them. Of course they had the outstanding Maxim Defense PDX with them as well as several of their accessories like the upcoming SIG MPX stock and their M-RAX rails.

The first gun that we spent a bit of quality time with was a full auto M4 lower sporting a Maxim Defense PDX upper. Maxim tells us that they will not only be offering the PDX as a complete rifle, but they also offer upgrade kits that departments can pin onto their existing M4s. The department has the choice of just ordering the complete upper or they can order a complete conversion kit that also includes the ultra-compact stock.

Maxim Defense did share that they would be debuting a .300 Blackout variant of the PDX at the 2019 NRA Annual Meetings, which has us pretty damned excited.

Pricing for the upper is $1,299 MSRP, the conversion kit is $1,799 MSRP, and the complete rifle will set you back $2,299 MSRP. Currently, pre-orders get a bit of a discount that brings the price of a complete PDX to $1,995. Pre-Orders will ship out sometime in April of 2019.


Maxim Defense also had a selection of their M-RAX rails on display that we are just flat out enamored by. The M-RAX makes the already simple MLOK attachment method crazy easy to use. No more chewed up T nuts or having to pull the rail section off to slightly tighten it and then try again. We spent some time playing with the M-RAX a bit and found it to not only be clever, but so easy to use. You drop the rail into the slots, push your wrench in to lift the T nut and rotate 90-degrees, drop the T nut back down and tighten. Cake.


The Maxim Defense M-RAX rail sections start at an MSRP of $39.95 for a seven slot, two screw model and goes up to $84.95 for the 23 slot, 6 screw version. Find them on the Maxim Defense website.

We checked out the final prototypes of the Maxim Defense SIG MPX arm brace and also the CQB stock, which is already available on their site. Maxim did show the MPX parts off at SHOT but only had a 3d printed prototype for the brace. We really dug the pistol brace variant, it should be pretty popular for those MPX pistol owners that want the most compact package possible.

The Maxim Defense CQB stock for the SIG MPX has an MSRP of $329.95 and can be found on their website now. The SIG MPX arm brace just came off the molds in time for Big 3 East, we will follow up with more information later.


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