So I got my Form 1 back a few weeks ago and have been putting some finishing touches on my Gen 1 MPX. I have a complete list of accessories and services that I used below for anyone who would like to replicate any part of what I did.

Stock extended:


Stock collapsed:


The main two things I'd like to review here are the Safety Harbor Firearms (SHF) KES telescoping stock and the Geissele G2S-E trigger, which I installed yesterday. I have also reviewed a few other items.

Regarding a comparison between the SHF KES stock and the factory Sig telescoping stock, I have played with the Sig stock at a local gun shop on a carbine and thought it sucked. The button and rods were stiff and there was nothing smooth about any of it. The SHF KES stock is the polar opposite. Everything about it is smooth with a satisfyingly positive lockup at each locked position. It is simple to disassemble if you need to dismount the stock piece from the rail mount. Mounting it took some figuring out, but the included hex wrench made it simple once I understood the instruction sheet. I emailed the manufacturer, suggesting they come up with an illustrated version. They are working on it. The mount is very solid once installed. I did a comparison of the collapsed length in Microsoft Word:


You can see that the collapsed length is shorter. When fully extended, the dimension from the front surface of the handguard to the rear of the buttpad is 25 inches.

I looked at all available stock options and decided on this one, which has not really been mentioned or reviewed anywhere. I cannot say enough good things about the SHF KES stock from functional, aesthetic and ergonomic standpoints. The hard-coat anodized finish is also very nice. I give it five out of five stars without any reservations at all.

Regarding the trigger, I have had a Geissele Adjustable Hi-Speed in my LWRC AR since 2008. It has been totally worth the money and feels great. The quality is phenomenal. So, when I first pulled the factory trigger on my MPX, I knew I was going to have to do something different. I saw forum posts about Geissele recommending the SSA or SSA-E for certain mechanical purposes that escape me at the moment, but I also saw that the G2S was a lower cost alternative due to the reduced amount of surface area that magnaflux particle (MP) inspection is performed. As long as the critical areas are done, I'm happy. However, I was interested in getting something like the enhanced version of the SSA, the SSA-E, except at a lower cost. Brownells is the exclusive distributor for such a trigger, the G2S-E, which has an identical description to that of the SSA-E, including the "candy cane-like second stage." It was $180 plus shipping, which compares favorably to the $240 price of the SSA-E. Installation wasn't bad, but wrestling the hammer to the point that the pin would insert was a trick or two. I omitted the Sig factory trigger bridge, as it interfered with the disconnector. Since Bill Geissele stands behind his warranty, including use in the MPX, I'm not concerned about the Sig warranty reportedly being voided by using parts other than theirs. If theirs didn't suck compared to the alternatives, people wouldn't be compelled to.
After installation and a functional check per the instructions, it was time to try it.

All I can say is WOW. Look up any Youtube review of the SSA-E and you will see what this thing is about. There is a 2.3 lb first stage and then a very light 1.2 lb 2nd stage. The term "candy cane-like" is very accurate. It just breaks. I wanted something that I could feel some travel and then be able to control when it fires. This thing totally delivers. If I want to do fast follow-ups, it does that too. The lock time is shorter too. It was totally worth the time, consideration and money. I don't regret not getting the G2S-E at all. Five stars.

I received my LaRue Covert Case last week. This is the best layout I could come up with so far:




Once I get my Silencerco Omega 9K suppressor (my dealer is currently waiting on the Form 3, so I have no idea what effect 41P will have on my Form 4 wait time), I think I will be able to set it up better. The suppressor that is mounted now is my old YHM Cobra 40. I have the older version of the LaRue Covert Case for my AR and have always loved it. The smaller size is worth having to break down the AR. It is the perfect case for an SBR project. Five stars.

Also, I have to mention the laser engraving I had done by Tar Heel State Firearms. They did the work the same day they got my lower receiver, put it exactly where I wanted it and shipped it out that same day. The price was right at $30 and the resultant finish is perfect. Five stars.

Laser engraving:


I also bought a wire charging handle stabilizer on Gunbroker. I did not feel like figuring out the dimensions and such and this thing looks like it was made on a CNC wire bending machine. It was $21 shipped, which seems steep for a piece of wire but the time savings made it worth it. It installs easy (instructions are included) and works as advertised. 5 stars. Link is below.

I have no ties to any of these companies. I am just a satisfied customer. I hope this review helps someone with their MPX project.

Links to reviewed items and services:

Stock (Multi-Position):
KES MPX - Safety Harbor Firearms

Geissele 2 Stage Enhanced (G2S-E) Trigger:
http://www.brownells.com/rifle-parts/triggers-parts/triggers/b-g2s-e-geissele-2-stage-enhanced-trigger-sku100014358-67223-138461.aspx

LaRue Covert Case (Charcoal):
LaRue Covert Rifle Case, MkII | LaRue Tactical

SBR Laser Engraving:
Tar Heel State Firearms - SBR Laser Engraving

Charging Handle Stabilizer:
Sig MPX Charging Handle Stabilizer -Free Shipping- : Other Gun Accessories & Parts at GunBroker.com

All other items and services:

Magazines:
SIG SAUER MPX Accessory Essentials Kit, 9mm, 30 rounds, Black

Aimpoint T-1 Micro With Absolute Co-Witness Throw-Lever Mount:
Aimpoint Micro T-1 2MOA/M4 QD Mount Combo | LaRue Tactical

Tango Down T-1 IO Cover (Black):
https://tangodown.com/shop/io-cover/

SureFire Mini Scout Light M300C (no Tapeswitch) w/LT752:
SureFire Mini Scout Light M300C (no Tapeswitch) w/LT752 | LaRue Tactical

Magpul MIAD Grip (Black):
https://www.magpul.com/products/miad-gen-1-1-grip-kit-type-1

Magpul MIAD Battery Compartment (Black):
https://www.magpul.com/products/miad-moe-cr123a-battery-storage-core

Blue Force Gear Padded Vickers Sling:
https://www.blueforcegear.com/padded-vickers-sling

Blue Force Gear Burnsed Socket:
https://www.blueforcegear.com/burnsed-socket.html

Blue Force Gear Rapid Emergency Detachment (RED) Sling Swivel:
https://www.blueforcegear.com/rapid-emergency-detachment-swivel-red-swivel.html

GGG Enhanced Sling Swivel:
Sling Swivels | Sling Mounts | QD Sling Swivel and Mount

Magpul RSA QD Rail Sling Attachment
https://www.magpul.com/products/rsa-qd

Silencerco Omega 9k Suppressor (Local gun shop - awaiting Form 3):
https://silencerco.com/silencers/omega-9k/

Barrel cut to 4.5” and rethreaded to 14.5mm X 1 LH to fit old YHM Cobra 40 suppressor:
Fort Daniel Inc.

MPX Gen1 Handguard Picatinny Rail Adapter 2 Inch:
SIG SAUER 556XI, MCX Handguard Rail Adapter 2 Inch

Not yet purchased:

Troy Tritium Folding Sights:
https://troyind.com/products/hk-folding-sight-tritium-blk

https://troyind.com/products/rear-folding-sight-tritium-blk

Very nice write up and pics!

The charging handle wire looks interesting. Any idea what material it's made of and can you check the wear of the wire and charging handle after a while?

I am the spring's manufacturer.

As a business at the launching point, even specific details as basic as a darn spring need to be protected until I am solvent.

That said, I will guarantee that I am using high quality, spring tempered steel wire, made in America, by Americans.

I have over 2500 rounds through my MPX with my stabilizer installed, with little to no significant wear to the Charging Handle (C/H) and zero wear to the lower. All though I lock before I load a fresh weapon and use the bolt release; reducing the potential for C/H gouging -even with Sig's "improved' Gen 2 handles- I cycle my weapon more than most and my lower still looks great! Only the one small mark I got when I first recognized the issue the day I got it.
In addition to making the spring, I also took the ledge off of the bottom of my Gen 1 C/H with a Dremel. Which is all Sig Sauer has chosen to do about the issue in Gen 2 versions. Something I would also recommend to Chase now that I think about it...

Just for laughs I sent one to Sig a couple weeks ago. No response.... But I did offer a permanent and 'factory quality' solution to the issue that wouldn't create a Gen 3. I really wish they would call me but they probably won't. O well.

Although an outstanding concept, Sig really phoned it in on a few key components. Good for me I guess! I've sold 60 springs so far...

Its a paper clip.   A bent paper clip.

Not exactly a paper clip but there is a guy that did make a paperclip work in a blog somewhere. Have at it friend.

What I'm offering is a high quality solution to a problem with a weapon system, offering an immediate fix as I work to develop my permanent solution..

Profits from the sale of this spring are going right back to that further development. That's how business works. Now you know I guess.

As a matter of fact, thanks to Chase, the spring he linked sold already. Here's a new listing if you want to have a part thats actually built from suitable material, has a coating that won't flake like the plating on paperclips, doesn't bend near as easily, and is actually designed to do the job it's being asked to do.....

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=550378059

I love that KES stock though! And I understand the issues Chase had with Sig Sauer's. In their defense, the telescoping lock mechanism is actually adjustable. Mine works great. It's just ugly. Looks like SHE got it right.

I love that KES stock though! And I understand the issues Chase had with Sig Sauer's. In their defense, the telescoping lock mechanism is actually adjustable. Mine works great. It's just ugly. Looks like SHE got it right.

Thanks, Lighter. I emailed you yesterday about these, and mailed payment today for one!

Sig Sauer called me today... I asked for them to consider adopting my other permanent design... Waiting for another call back now.

Thanks for the purchase nine.

I have an advanced installation procedure for the spring I will be posting shortly. It involves burning a small grove into the rubber bumper. More later.

Damn nice OP. How much you got into it?

No idea. I just keep buying whatever is next on the list.

Sig Sauer called me back today. This time I spoke to product manager John Brassier. Long story short, Sig Sauer couldn't care less about stabilizing their proprietary charging handle, the 67+ customers benefiting from my design or the countless MPX GEN 1 and 2 variants suffering receiver gouge ... Go figure.

Savages!
This is good news for your business model.

cool..Im in for one soon.  I tried making one out of a paper clip a couple of times and the end result left me feeling retarded.  well worth spending 21 bucks on for me...

I rearranged the LaRue Covert Case this evening:


And I picked up a few more magazines that were on sale, bringing the total to fifteen:


Here is a link to the sale-priced $44.99 MPX Gen 1 thirty round magazines:
https://www.preppergunshop.com/mpx-magazine-sig-mag-mpx-9mm-30rd.html

I have no business relationship with this vendor other than being a happy customer helping other people to get a great deal on these.