I recently had the opportunity to dive a bit deeper into one of the 308 battle rifles being compared for the InRangeTV/P&S collaboration video shoot. Since Karl will be releasing plenty of high quality video content comparing the various guns, I will not get into that. I wanted to specifically look at the SOLGW MK10 in the role of a heavier calibered carbine compared to a 5.56 gun. I will go into some velocity/accuracy testing. POI shift with suppressors, reliability, and finally thinking about using the MK10 as a replacement for the 5.56 rifle.
The MK10 comes with several upgraded controls as options. First, there were a few options on this particular gun that I would have preferred something different. SOLGW offers a “build your own” MK10 where you can select your preferred parts from muzzle device to stock, and most options in-between. I would have gone with an ambi mag release to compliment the ambi safety for example. I would have also had them install my preferred BCM grip instead of the rubber coated MOE+ grip. The forward controls design bolt release was excellent, and the Radian charging handle was, as expected, just right. I also appreciated the ambi bolt release on the right side of all MK10 rifles, and sending the bolt forward after a reload was easy. Some other 308 AR-pattern guns have ambi bolt releases, but none have been so easy to use. Many required a significantly harder push with the thumb to get them to work, but not on the MK10. It was unobtrusive while also having plenty of leverage to close the bolt. Trigger was the basic Sons of Liberty ‘liberty fighting trigger’ that appears to be a slicked up mil spec trigger a’la the ALG ACT or BCM PNT trigger. True it isn’t a two stage match trigger, but it falls right in line with the SOLGW mentality of reliability over all, and was perfectly usable and problem-free. Once again you can have just about any quality trigger installed in your own MK10 from the factory, or replace it later on.
Most of the ‘carbine’ type shooting was done with Magtech M80. Magtech makes a variety of smart ammunition options, and everything I have shot from them has been reliable. I also used Hornady American Gunner 155 grain BTHP, HSM reman loaded with a 168 grain Sierra MatchKing HPBT, Hornady TAP with a 168 A-Max, and Federal 168 grain Tactical Bonded. In my opinion, this MK10 is intended to be used as a carbine, not a DMR. I was very happy to see the Federal bonded ammo shoot under 2” 10 shot groups, as a bonded bullet of some sort would be what I would likely use in this gun, and save the HPBT match ammo for something set-up for a precision role.
For more of the test, I shot the MK10 with a Sandman-K attached to the NOX muzzle device (more on that later), but I also tested POI shift and velocity differences with a bare muzzle, the Sandman K, and Sandman S. The POI shifting was not extensive, but 5 round groups shot back-to-back in each configuration revealed less than 1 MOA shift combined. I also tracked velocity on these groups and averages were as follows:
NOX only: 2383
In this instance adding a suppressor, and then a longer suppressor, increased velocity just slightly. As always, test your own equipment for POI shift and velocity changes when adding a can.
When it comes to suppressing the MK10, I had both the Sandman S and K on the range, which both work very well on the SOLGW NOX muzzle device, a sort of surefire warcomp-style hybrid muzzle device compatible with the Dead Air keymount system. Starting with the S, I immediately noticed significant gas to the face, especially when shooting left-handed (as I, being left-handed, often do). I shot groups with both cans for velocity and POI shift purposes, but for the remainder of the shooting, I installed the K can and felt no adverse gas to the face.
Suppressors obviously change the pressures and cycling characteristics of almost any semi-auto firearm, and the MK10 is no different. It was specifically designed for reliability, so having extra gas, especially when suppressed with a full sized can, should not be a surprise, but something of note for potential buyers. I found using the Sandman-K to be much more pleasant, and fit the idea of a heavier carbine better, especially on a 16” barrel.
As far as the NOX muzzle device specifically, it was an interesting muzzle device to work with, especially on a 7.62 gun. I also have a 1/2X28 for a 5.56 gun I am interested in testing in the near future, but as of this writing I have only used it on the MK10. The NOX is intended to be timed with the middle opening between the flash hiding tines at 12 o’clock, and the sets of three compensating holes at 12 and 3. This is great for shooting right handed, and especially on the 308 it helped with both muzzle rise as well as the tendency of the gun to lift off to the right side. However, the small amount of shooting I did without the Sandman exacerbated the gun’s tendency to move off target to the left when shooting left handed. Obviously this is to be expected, and the tuning of the gun for right handed shooting decreases performance when shooting lefty. There simply is no free lunch. I would be interested in a NOX with compensating ports at both 3 and 9, similar to a neutrally-timed warcomp, as an ambi solution that still maintains some amount of control over muzzle rise. For someone shooting mostly left-handed, the NOX can be timed to advantage shooting off the left shoulder. To conclude, the NOX performs as advertised, and works very well keeping the gun on target when shooting right handed. For someone shooting off of both shoulders regularly, a standard Dead Air flash hider might serve your purposes better.
As previously mentioned, the MK10 was built to be, above anything else, reliable. In the over 500 rounds I shot through the gun (most of which were suppressed), it was exactly that.
With the exception of a single failure on the two occasions I ran a Magpul D50 as fast as I could pull the trigger, the gun just kept working. That was shooting in the heat, from various prone positions on a dusty range, and at times shooting a significant amount of ammo in a short time. After the first malfunction, I took the bolt out of the gun and seeing it was both filthy dirty and bone dry, I reapplied lube (but did not clean it). I feel confident in saying that I could not physically carry enough ammo to shoot that would get a properly maintained MK10 to a point of malfunctioning. While the 5.56 AR15 seems to have been essentially decoded to the point where any company with the integrity to build with quality parts and decent QC can make a reliable gun. The 7.62 rifles are a whole different animal, and having a AR-style rifle in 308 that keeps up with its smaller counterpart in reliability is not common.
Running both the Sandman-K and S, unsuppressed, and with six different types of ammo is impressive. As adjustable gas block, according to Sons of Liberty, is an unacceptable potential failure point, so seeing the gun run in all those configurations with such a range of ammo was a pleasant surprise. No doubt hot ammo and a suppressor leads to a bit more recoil, but once again, reliability and durability were the key goals with this rifle.
INSTEAD OF 5.56?
I’m confident in the accuracy, reliability, and durability of the MK10. The question to ask at the end is, how does it perform compared to a 5.56 gun? Also, when would you want to use a MK10 instead of the 5.56 AR that most of us already own and use? To set a baseline answer to this question, I took my own trusty 5.56 rifle, and ran all of the same tests that were done with the MK10, just to see the difference. The following illustrations show what happened.
As a summary of the data collected, as well as my personal experience shooting the two calibers head-to-head, a few notable results stick out:
1-In every metric, the 7.62 was slower than the 5.56; splits and reloads at all distances, and transitions between steel targets.
2-As distance or target difficulty increases, the MK10 begins to catch the lower recoiling, lighter 5.56. You give up more time in transitions or multiple shots up close using the MK10.
3-You also give up capacity, with 20-25 round magazines as standard versus 30. I will not even approach the subject of ballistics comparisons between 7.62 and 5.56, but when deciding the equipment you want to use, it is very important to consider.
Is it worth it stepping up to the bigger caliber at the expense of some shooting performance? Only you can make that decision for yourself. Are you encountering larger animals more than people? Are intermediate barriers a consideration? What are the distances you are most likely to use your rifle at? Is added weight/length a factor? Hopefully the data here can help you determine the ideal equipment for your individual situation.
The MK10 is an impressive gun. It is adaptable to suppressors and wide varieties of ammunition with no adjustment needed for reliable function, eliminating adjustable mechanisms that might compromise reliability or durability. While heavier than a 5.56 gun, it is a very acceptable weight for a 7.62 semi auto. It is readily customizable to the individual user in ways that other 308 battle rifles are not. It retains the familiar manual of arms as the AR15. Reliability-wise it seems to just run and run. If I determined a semi auto 7.62 was needed for my work or other situations, I would give the MK10 a serious consideration. Similar to the Chamber’s Custom 2011 I shot, this gun is currently out of my price range, and I do not currently have a need that it could fill. However, I can appreciate it as a viable option for many others who use long guns in a professional or competitive arena where you need a rifle you can count on, and require different capabilities than a 5.56 rifle. For you, consider the Sons of Liberty MK10.