EmptorMaven

I spent some time at the range with a chronograph, my short-barreled XCR, and my newest 5.56mm suppressor: HTG’s Eureka-4. The Eureka is 4.6″ long and weighs only 15 ounces. It extends the gun’s overall length only 2.8″ more than the standard flash suppressor it replaces, making it ideal for a compact, CQB-style carbine like this.

George Vais, who patented and developed the HTG suppressors, assured me that the Eureka is designed to absorb the higher muzzle pressures of shortened 5.56mm barrels, which some people fear will erode the blast baffles of cans not designed for that abuse. Granted, my 11″ barrel isn’t remarkably short given that some people run these rounds through 7.5″ barrels. At 11″ even the standard flash suppressor does a decent job moderating the muzzle blast, so shooting this XCR is no harsher than any other carbine I have shot in this caliber.

With the silencer attached, the gas piston valve can be turned to its lowest setting (“S”) and the gun still cycles reliably. This is thanks to the longer backpressure curve that a silencer maintains. However, a consequence of putting rounds designed for 20″ barrels through a system this short is that a significant amount of propellant gas blows back through the ejection port, which is not the most pleasant thing to have venting in front of your face. If I had to do this all day I’d probably wear goggles to keep it from irritating my eyes.

Without the suppressor mounted I turn the gas valve to its highest setting (“4″), as is suggested during the first few-hundred round “break-in” period. Factory 55gr .223 loads that chronograph 3150fps out of my 24″ bolt gun leave the unsuppressed 11″ barrel at just over 2600fps. I was surprised to discover that the gun’s action can tap a lot of power out of the shots, even though with this barrel the propellant doesn’t reach the gas hole until 1.5″ from the muzzle: Turning the gas system from “4″ to off — essentially making this a bolt-action gun — the bullets gain an extra 250fps! (Of course, this extra velocity is accompanied by a more violent muzzle blast.)

Screwing the silencer on increases muzzle velocity even further (thanks to an effect known as “freebore boost“): With the gas system off and the silencer on this gun shoots factory 55gr bullets over 2930fps, which is not bad for a barrel assembly measuring just 14″ long overall. Turning the gas system back on to “S” drops velocity just below 2900fps. Out of curiosity I kept the silencer on and stepped the gas valve up a notch to “1,” which pounded the action harder, ejected the case further, and dropped muzzle velocity to 2830fps. Always one to test the limits, I then cranked the gas back up to “4″ and fired one round, at which point the action crushed the neck of the spent case and somehow produced a triple-feed malfunction!

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Via The Firearm Blog, spot prices for the metals used in ammunition (primarily copper, lead, and zinc) are approaching their 2008 records and the Economist reports that they are projected to stay high.

Granted, the price of ammunition over the last few years initially shot up not because of inflation in the cost of raw materials but rather because of a massive increase in demand: U.S. military operations were already straining production capacity when political panic following the 2008 election prompted civilian stockpiling. Manufacturers are only now beginning to catch up to the demand.

I had hoped that at this point prices would begin to fall back towards the levels we saw in the middle of the decade. But now it looks like raw material prices may keep the floor close to where we are right now.

The Robinson Armament XCR is a “modular weapon system” that was originally developed as a candidate for the USSOCOM SCAR program. Of course, FN Herstel won that government contract and just last year began marketing civilian variants of its SCAR rifle. Robinson, meanwhile, shifted its attention to the civilian market where it began selling the XCR in 2006. Even with the recent introduction of the Remington (formerly Bushmaster) ACR the XCR is still the most widely available and, at around $1600, reasonably priced SCAR-type civilian rifle. It sports the following features common to this type of firearm:

• Adjustable gas piston operating system
• Foldable stock
• Quick-change barrel
• Multiple-caliber conversion
• Monolithic upper receiver and rail system
• Ambidextrous, short-throw safety

An excellent comparison with other “third generation carbines” is maintained on this chart.

Features unique to the XCR include:

• Clever (and now patented) ambidextrous bolt catch, positioned just in front of the trigger guard.
• Excellent 3.5-pound trigger. This “enhanced trigger” was introduced in 2009, about the same time as their ambidextrous safety, and replaces the 6 pound trigger found in earlier versions.
• AR-15 compatible grip (the one shown here is the MagPul MIAD)
• Non-reciprocating charging handle
• 3-lug bolt (easier to clean)

Features currently lacking on the XCR include:

• Stock with adjustable length-of-pull and cheek height — although an “enhanced stock” is supposedly in development, and an optional adaptor allows any AR-15 stock to be installed.
• Ambidextrous magazine release (“in development”)
• Ambidextrous charging handle
• 1/9″ twist barrels are standard; 1/7″ to this point have been promised but hard to get.

A good critical review here summarizes common complaints about the XCR, most of which center on the fact that a lot of its hardware is screwed down instead of pinned. The XCR manual comes with a number of recommended points for applying red and blue loctite to keep screws in place.

In my opinion the XCR lower receiver is the ideal item to register as a Short-Barreled Rifle (SBR): The same XCR-L lower can then be fitted with uppers and barrels as short as 7.5″ as well as at least 3 caliber conversion kits (currently available: 5.56, 6.8SPC, and 7.62×39). The photos here show a standard 5.56mm upper with an 11″ barrel, which makes it 30.5″ long overall, and only 22.5″ with the stock folded.

A few other noteworthy details:

• The gas system has six positions: Off, suppressor, and standard settings numbered 1-4.
• The folding stock includes a quick-detach sling swivel slot for a single-point sling.
• Company representatives frequent the official online forum.
• The company has been responsive to my problems and requests via both phone and Email.