Tag Archives: firearms

We’re finishing up “M” Week at the blog. Monday was Mosin. Wednesday we ran with Marlin. Today’s “M” is for Ruger’s MPR version of their AR-556.

I finally gave in to the AR-style rifle bug. But give in I did, after a lot of research. I had no desire to ever travel this road again, and I didn’t want to make a mistake, so I studied for months. Along the way I discovered a lot of information that directed me towards today’s subject — the Ruger AR-556 MPR (Multi-Purpose Rifle).

What were the other contenders, and how did I finally arrive at the AR-556 MPR? Let’s explore that for a moment, bearing in mind that my choices won’t necessarily align with your choices.

I’ll start with a brief look at the original AR-15 designed around the .223 Remington round. The .223 Remington was developed for the commercial varmint rifle market back in 1957, and by 1963 the first rifles chambered for this round became available. Eugene Stoner got involved when Remington invited him to scale down his existing ArmaLite AR-10 to handle the .223. The result was the ArmaLite AR-15, which like the AR-10 uses a unique direct gas impingement design (okay, not technically correct, but “direct impingement” is the popular name for it) that directed gas directly into the bolt carrier to cycle the weapon. Mr. Stoner set the barrel length at 20 inches/50.8 cm to make full use of the propellant in the .223 Remington, as barrels shorter than that length resulted in incomplete ignition of the propellant before the bullet exited the muzzle. That 20 inches also allowed for an optimal “rifle length” gas system, which would reduce recoil, thus lessening the stress on the bolt and buffer, and introduce less gas-fouling into the bolt carrier. Keep that in mind, as shorter barrels result in a shorter gas system, more recoil, faster bolt speeds causing more stress, and hotter gases getting introduced into the bolt carrier.

About this time the U.S. Air Force were looking for an alternative to their M1 and M2 carbines, and the Army were considering something easier to handle in full-automatic than their M14. This led Colt to purchase the rights for Mr. Stoner’s AR-15 from ArmaLite (contrary to myth the “AR” in “AR-15” stands for ” ArmaLite Rifle, not “Assault Rifle”). Colt then further developed the now “Colt” AR-15 into the M-16 chambered for the M193 cartridge. The M193 (not to be confused with the later similar NATO 5.56 mm round developed by FN in the 1970s) is basically a 55-grain/3.56 gram version of the .223 Remington. After some trial and error, Colt settled on 6-groove rifling with a 1:12/ 1:30.48 cm right-hand twist optimized for the lightweight 55-grain round.

Yeah . . . just  try to find a rifle-length gas system on an AR-style rifle today. There are some out there, but you’ll pay for it. The rage today is to go tacti-cool and get the barrel length down to the legal non-NFA minimum of 16 inches/40.6 cm barrel. That’s because the military’s current M4 version has a ridiculously short 14.5-inch/36.8 cm barrel and, hey, everybody wants that military look regardless of how the rifle performs in most civilian applications. (Again, don’t take offense; I’m describing my preferences here, not necessarily your preferences.)

But remember what you give up for the modern Battle-of-Fallujah look — that rifle-length gas system goes by the wayside. That gets you incomplete burning of propellant; which in turn results in a reduction in muzzle velocity and energy; increased muzzle flash from the still-burning propellant blasting out the muzzle; increased bolt speed with the additional wear-and-tear that entails; and more fouling in the receiver from hotter, unburnt gases. Sorry, but I’m just not seeing any real advantages here for civilian applications. It’s not as if I’ll be using a shortened AR-style rifle with a carbine-length gas system in an urban warfare environment, or even to protect the homestead. In an AR-style rifle I’d rather have the longer range, lower recoil, and all the other advantages that a full-length gas system affords.

Again, that’s my choice meeting my needs. When you go shopping for an AR-style rifle, you need to evaluate what works best for you. And if you like what I’m about to describe on the MPR version of Ruger’s AR-556 but want a shorter barrel, you’re in luck. Ruger also makes the MPR in a 16.1-inch version (Model 8542). You can also get the MPR chambered for .350 Legend (Model 8532) and .450 Bushmaster (Model 8522). Unfortunately, if you want .300 AAC Blackout, you must go with Ruger’s standard AR-556 (Model 8530) or get the “pistol” version (Model 8572) with an even sillier 10.5-inch/26.7 cm barrel.

Here is the list of contenders that in the end were vying for my dollars:

• SIG Sauer M400 Tread: SIG has discontinued anything longer than a 16-inch barrel; you pay for the SIG name.
• FN 15 Military Collector M16: 20-inch barrel available; but lacked a lot of features for an MSRP of $1,749.
• Colt: The original; you can’t go wrong with the Prancing Pony, but only the expensive M16A1 Retro Reissue offered a rifle-length gas system . . . at $2,499 MSRP!
• Springfield Saint: Barrel maxes out at 16 inches.
• Smith & Wesson M&P 15 Competition: This one comes closest yet to the MPR:
  • Pros: 18-inch barrel; rifle-length gas system; two-stage match trigger; 15-inch free-float M-LOK compatible handguard; full-length rail; adjustable buttstock.
  • Cons: Heavier than the MPR; MSRP is $700 higher than the MPR with nothing to show for the additional cost.

First, the relevant technical statistics for the Ruger® AR-556® MPR (Model 8514):

• Caliber: 5.56 NATO/.223 Remington (other calibers available; see text)
• Length: 35 to 38.25 inches/88.9 to 97.2 cm
• Length of pull: 11.1 to 14.4 inches/28.2 to 36.6 cm
• Weight: 6.8 pounds/3.1 kg
• Gas system: Rifle length
• Buffer: Mil-Spec (Military Specification) buffer tube
• Barrel: 18 inches/45.7 cm
• Barrel twist: 1:8, 5-groove, right hand
• Barrel forging and metallurgy: Cold hammer-forged; 4041 chromium-molybdenum alloy steel; nitride lining
• Barrel attachment thread pattern: ½”x28
• Lower specifications: CNC-machined 7075-T6 aluminum forgings; Type III (Mil-Spec) hard coat anodization
• Sights: None included in keeping with the free-floating barrel design

Other included goodies:

• Trigger: Ruger’s Elite 452® two-stage trigger (a huge plus for this rifle) with a claimed 4.5-pound/2-kilogram pull
• Accessory Rail: Full length Picatinny M1913 rail
• Handguard: 15-inch/38.1 cm free-floating Magpul® handguard with:
  • M-LOK® Slots at 3, 6, and 9 O’clock (eight slots per O’clock position)
  • Additional single M-LOK slots at 1:30, 4:30, 7:30, and 10:30 positions

• Buttstock: Magpul MOE® (Magpul Original Equipment) SL® (Slim Line) collapsible buttstock
• Pistol grip: Magpul MOE grip
• Capacity: The MPR comes with one 30-round Magpul PMAG® Gen-2 MOE magazine (a pet peeve of mine; come on, Ruger, you can do better than just one magazine)
• Owner’s Manual: Of course
• Safety lock: Cable type key lock
• Box: Cheap cardboard, of course

Now let’s take a look at the rifle.  First off, that scope you see mounted does not come with the AR-556 MPR. Indeed, since this rifle has a free-float barrel, it does not come with a sight of any type — not even the usual combination gas block/front sight most associated with this type of rifle. As such, you’ll have to cough up some money upfront to fix that. The scope you see mounted here is a Vortex Crossfire II 1-4×24 with Vortex’s V-Brite red dot.

Also not included was the two-point sling you see pictured, nor the M-LOK Quick Dismount (QD) rail attachment. The MOE SL buttstock does however have a QD attachment point, in addition to a slot for your sling if you prefer.

But no matter what sight you choose to mount, there’s nearly 20 inches/51 cm of slot “rail” estate along the rail atop the MPR’s flat upper receiver. Go with iron sights, red dot, red dot with magnifier, low-power scope, high-power scope, night scope, or even optics co-witnessed with iron sights if you wish. The options are limited only by your imagination and your wallet.

Now, what about Ruger’s claimed 4.5-pound/2.04 kg Elite 452 trigger? Turns out they fudged on that one. The pull worked out closer to 4.17 pounds, but I’m not going to quibble when it’s to my advantage. The actual five-pull average came in at a mere 4 pounds 2.7 ounces/1.89 kg. Trigger reset is so miniscule I had trouble measuring it, but my best eyeball guesstimate puts it at around an eighth of an inch, or about 3 mm.

I’ve yet to fire the AR-556 MPR, so I haven’t even had the opportunity to sight in the Crossfire II. But I can tell you how I perceive the handling characteristics thus far. The MPR is well balanced and easy to handle. It’s both light and comfortable to carry, and quick to get on target when the sling is properly adjusted. All controls are just where one would expect on any AR-style rifle, so there are no surprises here and they are all easy to manipulate . . . if you’re righthanded; none of the controls are ambidextrous.

Fit and finish I would rate as good. The MPR certainly looks good. There was one minor flaw in the hard coat anodization on the edge of the magazine well (see below). But that’s a quibble. It’s not worth the time and effort for a trip back to the mothership for a rifle that is meant to be used.

A word of caution: make sure you disassemble your MPR and check for copious amounts of lubrication. One of the things I really appreciate about Ruger is that they way overengineer nearly everything they make, but they also love to overlubricate. In the case of this MPR, there was far too much lubricant inside the bolt carrier and on the tail of the bolt. I hate to think how much carbon would have cooked onto those surfaces if I hadn’t wiped them down. Other areas were positively dripping with lubrication as well, but that’s been remedied.

Overall, I’m impressed. But then I’m also a novice in the AR market, so there’s that. Perhaps I’m just easily impressed. But I don’t believe that’s the case here. For all the features Ruger threw into this AR-556 variant, the MPR is an impressive rifle at a price point hundreds less than anything comparable in a nationally known and respected brand.

That concludes this week’s firearms series. If you’re not a fan, do not despair.

Next week this blog returns to travel the photography. That series will start in Ireland, head transatlantic with a stop in Ponta Delgada in the Azores, continue into Key West for some sunset photos, then head over to the Mayan ruins of Chichen Itza on the Yucatán Peninsula.