MK12 SPR – Special Purpose Rifle with Navy SEAL Monty Leclair

Monty Leclair – US Navy Seal and owner of Centurion Arms – Photo screenshot via Vickers Tactical

(Editor’s Note: This article was originally posted in November 2018) Monty Leclair is a US Navy SEAL and the owner of Centurion Arms.  Few know more about the MK12 SPR than Monty, who has spent a career with and behind the rifle.  In an industry where there’s always a “latest and greatest,” the MK12 SPR has remained a classic constant, and for good reason.

When I grab a scoped rifle, my ultra-reliable personal MK12 Mod 1 remains my go-to.   I know I’m not the only one I know who feels this way.  To talk more about the MK12 SPR, and why it’s one of the best platforms to build your SPR around, we reached out to Monty.

Q:  Monty, you’re a massive source of knowledge when it comes to firearms. Larry Vickers said you were the most “weapons-savvy SEAL he had ever met.”  I know that when it comes to the MK12 SPR, you are most certainly the man to call.  Can you give our readers just a bit of background?

A:  Before I joined the military, I always had a strong interest in firearms. I built my first AR when I was 18. Back then, I was always interested in doing some type of special operations stuff. I ended up joining the military to be a SEAL after I had heard what they were.  There, I got some more experience with shooting and firearms stuff.

When I was a little bit more senior, I worked at WARCOM (United States Naval Special Warfare Command) dealing with weapons development.  Being a “gun guy” is how I ended up in that seat.  I had a lot of weapons knowledge I’d gathered on my own…learning how to build 1911 handguns with Larry Vickers, learning how to build sniper rifles and bolt guns on my own…learning the machine work side of it.

Larry Vickers and Monty Leclair discuss the MK12, part 1…one of the best videos ever done on the MK12 SPR.

A Unique Learning Opportunity

Over at WARCOM, I was involved with a lot of the weapons programs that were coming around like the MK12, SCAR, the PSR.  That helped introduce me to a lot of people in the industry.  I learned a lot about technology and also got a lot of good inside information about military specs and why they were the way they were.  There, I was also able to visit weapons factories and really see what works and what doesn’t work.

With this information…later on in my career, I started Centurion Arms.  We began building uppers and MK12 stuff…things I had seen in the military that I just generally liked, but particularly the MK12.

Q:  You’ve seen things from development side, from the end-user perspective, but now also as a manufacturer.  What’s your perspective on the longevity of the MK12?  Especially when it seems there’s always something coming out that claims to be the next best thing…

A:  One of the big things I see in the marketplace to avoid is most of the “latest and greatest” stuff.  I don’t want to call out specific fads and bash a specific company.  But, I see fads take off in the industry today that were things the military and a lot of larger corporations had tried out five or sometimes ten years prior.

These things never went anywhere because they didn’t offer any real improvements. But, then I see them later being marketed very well on the civilian market.  And people take it hook, line and sinker.  What I would say is that people should wait to see on new technology.  Wait to see how it really pans out.

Marketing, Smoke & Mirrors

A lot of the information on the marketplace…if you could see behind the curtain I’ve seen behind…I’ll just say that a lot of stuff is marketing and smoke & mirrors.  People are getting marketing vs. what actually works.

Now, I do understand that everyone is always looking for the latest and greatest.  And of course, new technology does eventually come out…but it takes a while for it to pan out correctly.  You want to make sure it is actually beneficial.  I still see a lot of stuff out there today that is very popular in the marketplace that I don’t think, when you really get down to it, has the benefits that people claim.  People don’t realize the downside to it, or they simply don’t shoot enough to see the downsides in some of the fads.

 A U.S. Special Forces Soldier conducts rehearsal, training and pre-operation conformation on the MK 12 sniper rifle. U.S. Navy photo by Mass Communication Specialist 2nd Class Eli J. Medellin (RELEASED)

Q:  If there’s one thing the MK12 SPR has proven not to be…it’s a fad. 

A:  The beauty of the MK12 is that it came from a very specific need…military operators needing a good precision weapon for something that was 5-600 yards and in.  And yes, like you say…the gun is boiled down to everything that WORKS.   It has a quality stainless steel barrel with a good chamber that was meant to function with a specific type of ammo.  Now they did test the functionality of the weapons system with all of the military ammo so guys don’t have a problem with reliability, but it was really dedicated for running the 77-grain MK 262 projectiles.

Jack Carr recently wrote one of the best articles anywhere on the MK12.  Check out that article here.  You’ll notice Monty is mentioned at the end.

Near Universal Acceptance

One of the reasons this platform has been so long-lasting and has had such an impact is because I don’t know of a single operator out there that ever had one issued that ever had anything bad to say.

They always shot like a laser.  The suppressor always worked great.  The guns were long-lasting, reliable and hands-down, out of all my time in dealing with weapons programs in the military, the one program that had the least contention with it was the MK12.  Pretty much everybody liked it.  It had favorable reviews from everybody in what it offered.

We recently interviewed Ryan Cleckner for an article about long range precision shooting.  Ryan told us:  “My favorite gun, by far, was the MK12 SPR MOD 1 with the Knight’s Armament rail.”

It did exactly what it said it did, and did a good job at it.  It’s a perfect example of using technology that had been all fleshed out to make a great final product.

The MK12 is a shining example of the system working and the ability of government and industry being able to work together to get a product out in the field that can make a real difference.

C. Reed Knight, III – Knight’s Armament Co. – 11/2009
MK12 Mod 1

Q:  I had purchased my MK12 SPR from the guys over at High Caliber Sales.  Like Centurion Arms, they are a company that possesses a unique insight into the original request for the development of, and the refinement of the MK12 SPR.  With their work slowing down, Centurion Arms is the go-to company out there giving today’s shooters access to this incredible rifle.  Can you comment on that?

A:  At Centurion Arms, we have a lot of information and a lot of data here that other companies are just not exposed to.  I have all the experience and data about all the military testing the platform went through to be accepted.

I also have actual real-world operational experience with the gun overseas…in my hand, shooting at people with it.  Using it in combat myself, I have a unique understanding of issues that came up along the way, and how we went about fixing them.

Monty Leclair and Larry Vickers give an overview of the MK12…part 2.

Q:  There’s always more advanced weapons systems coming out.  Is there anything you’d recommend a shooter do to the MK12 SPR to perhaps modernize it a bit?

A:  The major components for the MK12 have not changed.  In the meantime, a good accessory might be a modern bipod, or perhaps put a good sling adapter on it.  As far as optics, put a good 2-10 power scope on it.  2-10 seems about right.  You could go to a 4-16 as well.  Good backup iron sights are a nice idea.  An offset red-dot is also not a bad choice as long as you’re training and working with it.

Removing the A2 Stock

Some people like to switch to a collapsible stock.  The reason the military didn’t is because the weapon still had full-auto capability, which did not prove to be reliable with the collapsible stock in full-auto.  But in semi-auto, they admit they didn’t have any issues with it…so you would see some operators switch to a collapsible stock and never use it in full auto.  In the field, they realized they were not going to be using the weapons system in full-auto anyway. So, a collapsible stock is not a bad modern upgrade, especially for a semi-auto platform.


Centurion MLOK CMR Rail – Photo by Zero7One

Nowadays, some people also might choose to put on one of our MLOK rails or even our C4 rail.  The C4 rail is still free-float, and still offers all the advantages of the Knight’s RAS system rail but is less expensive.  It’s also lighter, a little bit sleeker and lower profile.  It has built-in QD sling swivels so that could be an upgrade someone wants…as well as the possibility of using MLOK.  That way they can stay updated with all of the accessories that now are going with the MLOK platform.

Monty participates in the TacTV SPR Stress Test Challenge…

Q:  There’s a lot of builders out there who are cloners.  That can be a lot of fun and it’s always neat to own what feels like a part of history…but for those not opposed to an updated MK12 SPR, it just seems like such a great base to work from.  Can you talk a bit about that?

A: There is that crowd that wants wall-hangers and safe queens that are going to be into clones…and that’s acceptable. But there are still a lot of guys who are wanting to get the MK12 to run it and use it as a shooter.  They are ideal for use in competition, for entertainment, for varmint hunting. These shooters can stick with the proven MK12 platform in the sense that the barrel, bolt and ammunition all stay the same.   And, then they can go ahead and enhance it with some of the more modern updates. The major thing is the handguard as I mentioned.

SureFire SOCOM556 – A worthy replacement for the Allen Engineering  AEM5, should you want a QD option.  If not the Allen Engineering is still a great, affordable option.

The other thing is sometimes people prefer to change to SureFire suppressor. SureFire is a company that we deal with.   The original Allen Engineering is a great suppressor, but in today’s day and age, a lot of times people enjoy swapping suppressors onto different weapons systems with a quick detach mechanism.  For that, we have had good luck with the SureFire SOCOM.  They make a very solid product.

Q:  Being such an expert, can you give us any final advice with your builder’s hat on?

First off all, I’d say If someone is looking to build an SPR, the MK12 is still a reliable platform.  It’s valid and sound.  I think it’s important to understand what it is that makes these guns accurate, reliable and long-lasting.  Knowing quality parts is vital.

Centurion MLOK CMR Rail – Photo by Zero7One

Avoiding the Race to the Bottom

People need to stick with quality products.  This is because the one downturn the industry has taken is a race to the bottom on pricing.  I’d say if you are looking to buy or build a cheap rifle, you need to realize you get what you pay for.

The sad part is that behind the scenes…I’ve seen a lot of suppliers to higher-end companies have their quality go down, just trying to turn out numbers. They’re doing this to reduce price points so they can keep up with the lower end of the market. I almost feel like it has brought the entire industry down to a degree.  So again, I would caution builders to stay away from the budget stuff.  If you are serious about it and you need the performance, always stick with high-quality parts.


A tremendous thanks to Monty Leclair for taking the time to speak with us.  To learn more about Centurion Arms, be sure to check out their website.

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Bill Bronaugh
4 years ago

Hey folks, absolutely a great article on the Mk12. Mr. Leclair built my Mk12 upper for me and it IS my favorite and most cherished AR, and I have many. I just couldn’t think of anyone better to ask to put one together for me. I have the RECCE rifle from Kevin at HCS and it’s a fine rifle too but it’s not my Mk12 and unfortunately the barrel I got was way, way overgassed for non-suppressed use but I did get that straightened out and it is a fine shooting companion to the Mk12, it looks like a little… Read more »

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