I’ve had the UK/London Metropolitan Sig MCX for a couple of weeks now, and have shot it on the flat range, in shoot houses, day and night.



These are my thoughts, as a law-enforcement shooting instructor, on the pros and cons of this platform. This will contain both opinion and fact, surrounded by educated guesses, so this is intended to be my feedback, not an absolute.

The Sig MCX is a nice platform. It shares pretty much the same manual of arms with an AR-15 so anyone familiar with the AR will be able to transition with minimal fuss over to the MCX. The main differences are in immediate action/malfunction drills because working parts are not the same.

The MCX includes a lot of upgrades, most of which address wear items; I would expect to see a reduction in maintenance costs over time.

The primary upgrades are:

User replaceable barrel.
This allows caliber exchange and also very quick replacement of worn items.

Steel insert on the cam path.
This is a piston operated gun, so the cam pin would usually create wear over time on the upper receiver due to early and fast unlocking. This is cleverly designed so that the upper will survive whilst the wear area can be replaced.

Ambi Safety
This is interesting as the internal core is compatible with full auto even on the semi guns so there must be some supply chain savings for Sig there. The right hand side lever, as usual, will rub on everyone’s trigger finger.

MCX specific BCG and dual recoil rod
I have a later version of this in my guns (the early ones had NP3 coated carriers). It does use a standard firing pin, retainer and a somewhat normal bolt. Standard bolts can be interchanged.

Charging handle latch inserts
Steel roll pins are installed to stop wear of the charging handle on the upper receiver

Replaceable Forward Assist
This whole unit is replaceable, I’m not entirely sure why, I’ve never seen a worn out one.

The UK Police were, as far as I know, the first Law Enforcement agency to move over to the MCX platform for their rifles. As of this moment they seem to be limited to only the more specialized units, specifically the CT (Counter Terrorism) Unit.

The specific setup of the rifles is unique. It would be interesting to find out how/why certain decisions were made.

Here are some pictures of the UK Met with the MCX Rifles



One of my  actual guns is pictured below. It was built by Sig specifically for the UK Police contract, and at this time, there is no US availability. It is however, listed in the US LEO catalog, so I suspect it will be available in due course.



Upon initial viewings of the gun, and then when using it exactly as configured, several things about the UK police gun stand out as not ideal.

The biggest single ‘issue’ I have with the current configuration is the Phase 5 bolt release lever. This replaces the standard bolt catch and puts the lever inside the trigger guard. I don’t like things in trigger guards that are not triggers. Your finger should be used for one thing, which is pulling that trigger.
Just as the US police have seen many NDs pulling Glock triggers when making safe, the comparatively far less trained UK teams should not be using their trigger fingers for anything except making bad people stop.

Other issues for actual deployment are the single point sling. If they need to help a colleague out, or drag a hostage, what is happening with their gun? Single point slings should have been left behind when they changed from the MP5.



The placement of the front sight is odd; they have placed the sight on the last part of the fixed fore-end. This covers up the gas selection port (suppressed vs unsuppressed setting) making it harder to change, but more importantly, it seems like this was done because they didn’t trust the removeable handguard. The fore-end aligns using a woodruff key, I have personally removed and replaced it multiple times checking zero at various distances and found a complete return to zero.

None of the above issues are actually an issue with the Sig MCX platform itself.
Its certainly very possible and likely that the reason for some of the choices of config and the use/deployment of the guns are based on older knowledge as the Europeans do not have the training and experience available in the US.



Onto the actual gun itself. The only major change I needed to make comparatively to the AR15 is the position of the light. On a standard AR-15 it is very easy to locate the light on the side of the fore-end and the switch on the top picatinny.
Unfortunately, the Sig fore-end is huge and very tall, so the pressure switch for the light needs to go on the side, and the light needs to go on the bottom.


The gun has an 11.5” barrel, and with the self adjusting gas runs fine with 556 ammo. In fact, it even has now done just over 1000rds with low powered imported 55gr ammunition and in all of the rounds I have run through the gun, have not had one single malfunction. Reliability seems excellent, on par with a quality AR15 thus far.

The trigger is heavy, my gauge measures it as 8.5lbs, it is breaking in/getting smoother with use. I dislike heavy triggers as I can watch officers when dry firing pull the gun to the left as they struggle to overcome the pull weight.



The UK gun has the new telescoping stock, the one that is slightly shorter for use with the MCX (I think it works on the MPX too).  This is certainly better than the ‘kate moss’ folding stock as seen on most current MCXs as it allows for adjusting the length of pull. Thus users with body armor or smaller people can adjust it to their liking. The disadvantage is that it is shorter fully extended than a normal 6 position M4 stock so taller people may have issues. It is very comfortable to use, unlike an MP5 collapsible.

The recoil, I am guessing due to the dual spring design, is very slight. 556 recoil is comparable to a mid-length direct impingement system. It is certainly softer than a carbine gas system. It is not a smooth or soft as a mid-length system adjusted down to the minimum required to cycle the action, but that is an extreme comparison. Overall it allows for very quick follow up shots and it is nice to shoot.

With the Kate Moss stock, the gun is front heavy, noticeably so. With the telescoping stock it is still front heavy but it better balanced and easier to get used to.

The extra weight slows down movement of the gun a little but its still very manageable.

Performing the CSAT Standards I was faster with an AR SBR but still well under standards time with the MCX.

With all of my time using it, I identified several areas I wanted to improve for my own use.

An upgraded version was then developed.




I changed out the pistol grip for a BCM, this angle I find, is much more natural.

I also changed from the Streamlight TLR1 to a Surefire X300U, the remote pressure pad is better on the Surefire, as well as the lockout button being better designed. The light throw is also wider.

I replaced the takedown/pivot pins with Ti pins, the original ones lose their finish incredibly quickly when you are constantly removing the fore-end (as I did to test re-zero_. The Ti ones will not wear or deform easily.



I also replaced the large, average quality Sig BUIS with Magpul Pro units. Located in the correct places :-)

The factory trigger was also changed out for a Geissele SSA.

One of the biggest changes I made to operation is I replaced the standard bolt with an S7 tool steel relia-bolt. These have chamfered, stress relieved edges and upgraded the extractor too.  Considering the rest of the gun has so many upgrades I found it strange the bolt was not addressed.



To get away from single point sling issues the Sig sling mount was fitted. This comes with the MCX and is a lot profile, top rail mounted QD point.
With Night Vision the Aimpoint sight creates a bit of a tunnel, Aimpoints are amazing sights but when using NV regularly, the Trijicon MRO is a little better. The Phase 5 bolt catch was also swapped back to the original.

The BCM was removed and replaced with a ZeroBravo RHS.

Overall, the new MCX is a fine platform and with some minor configuration changes I think could be a very good rifle for the UK Police forces.

Thanks for the through report


Many have had problems with those, so I would definitely keep an eye on it. There are other options I would have chosen in replacement bolts.

Beautiful piece of kit you got issued. Thanks for sharing. Have you or any of your team mates run into any serviceability issues, FTF based off certain ammo types?  What mags you running? What distances have you shot out to on the flat range and how was the accuracy?  I love my MCX and have only done 50-200 yards but accuracy has been great.

Since the early ones that weren't heat treated correctly I have not seen any issues. Have you any links to recent issues with these?
 

Good stuff.   Too bad the rest of the citizens cannot own that. .

I know, you didn't ask for comments. ..

BTW.  Nice photos.

Cheers

Excellent review. Thanks for posting it.

Excellent!  Thank you for posting this!

Awesome!  How is your Sig support over there?  Do they reps or are you relying on folks in the states?

Great writeup, Thank you!

Support in the UK is good, it is an Austrian company after alll!!

Austrian? I believe it's a Swiss and German company.

SIG SAUER is an ISO 9001 certified company with over 800 employees. It is the largest member of a worldwide business group of firearms manufacturers that includes J.P. Sauer & Sohn and Blaser, Gmbh. in Germany and Swiss Arms AG in Switzerland.

Sorry, you are absolutely right, in my own dream world here.

As far as I know, all the support comes from the one importer (Edgar Brothers) but the SIG LEO sales people do a lot of support.

I mean it's close enough I guess

Agreed about the handguard. The round suppressor compatible hand guard looks to be more ergonomic.

I don't know about the product lot, but EAG posted an AAR of their 18-20-december-2015 class where a Sharps Relia-Bolt failed with two broken lugs around 2000 rounds. Could be an older bolt, impossible to say without asking the guy.

One thing occurred to me though. There has been much talk about the lack of reciprocating mass compared to an AR15. Even if it is just a little more, using an AR15 bolt with a full tail would be ever so slightly heavier than the MCX bolt.

S7 steel used in the Sharps is ever so slightly lighter than carpenter 158, but that difference should be negligible in something as small as a bolt.

To the OP: Thank you for sharing your experiences and observations with us. It is much appreciated.

Aren't the MCX's in use there US made?

   Great writeup and I have to say that is better than many magazine articles I have read over the years.  It is interesting that your rifle is front heavy as my Sig 556 is the same way.  Perhaps you could change out the forend for something lighter?

    Thanks again for taking the time to put that all together.

Thanks you very much for the write-up. Very informative and those are some great pictures you have there.