I reload for half a dozen guns in .308 Winchester. Reloading is a lot easier if you only have to neck-size fired cases. Until recently I kept all brass segregated by rifle, and only “full-length” case-sized brass that came out of semi-autos (which are under enough pressure during extraction to bulge the case body). Then I thought I’d get clever and see if any chambers were cross-compatible, allowing me to use brass fired in one gun in others without full resizing. Sure enough, a handful of fired cases suggested that all my bolt-guns were interchangeable.

However, since this apparent epiphany I have broken a CTR stock, a Savage bolt handle, and five cleaning rods in the process of extracting rounds stuck in chambers. I have also resolved to small-base-size any case that isn’t being reloaded for the bolt gun in which it was last fired. Here are some nuances I’ve learned.

Evidently fired case size isn’t consistent. Even though I’ve been using a single lot of brass, not all loads fully form the case to the chamber. Presumably even if I stuck with the same load the brass would exhibit different springback on subsequent reloadings as it work hardens.

I eventually discovered that my DTA chamber has a relatively large base, which led to my other painful discovery: “full-length” rifle sizing dies do not necessarily size the whole case. For example, when properly set, my Lee full-length .308 die doesn’t even cover the bottom quarter inch of a case. Only a “small-base” sizing die will ensure the entire case is squeezed back into spec.

My other irritating discovery is that few “case gauges” check for full chamber fit. The Wilson case gauges I had been using all along are actually overbored to ensure they can measure fire-formed brass. They are only meant to check headspace and trim length. The fact that a case clears a Wilson gauge is insufficient to determine whether it will chamber in any gun. The only gauge I could find to guarantee chamber fit is the blue JP Enterprises one in the middle of this picture:

The JP gauge is cut to the minimum SAAMI chamber spec, which means that if a round clears it and fails to chamber you’ve got a chamber problem, not a case size problem. But we’re talking about very fine tolerances. The round in the JP gauge in the picture is actually oversize enough to jam in my Savage. You can barely tell that by looking, but you can feel the base protruding ever-so-slightly at the rear of the gauge.
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The Barrett MRAD is a $5800 precision multi-caliber bolt-action rifle, shown here with a 24″ barrel in .338 Lapua Magnum, and a $500 quick-detach LRA bipod. The MRAD sets new standards in modularity, simplicity, and compatibility by combining a number of clever design features:

• Like most modular rifles its folding buttstock locks into place over the bolt handle. It adjusts for length-of-pull with a button, cheek height with a thumbscrew, and features a bottom rail for mounting a monopod.
• The upper is a beautifully milled if oddly anodized piece of aluminum with 30MOA of cant in the top rail.
• It uses robust and reasonably priced double-stack injection-molded 10-round magazines. (However they can only hold rounds up to 3.8″ long, which may limit the reloading envelope of heavy VLD bullets.)
• Upper and lower receivers separate with one lever and one captive drift pin.
• It accepts standard AR-style grips. It is shown here with a Magpul MOE.
• It uses a traditional AR-style short-throw safety.
• The bolt has an automatic self-lubricating dust cover.
• Its barrel can be rapidly changed out the front after removing two bolts, and reinstalled without losing zero.

After pivoting the gun open the bolt comes straight out. The safety can be pushed out without tools at which point the trigger module can be lifted out. The trigger itself deserves special attention: It is as simple as can be and elegantly executed. Adjustable down to 1.5 pounds, it breaks shots consistently with no creep or overtravel — an ideal specimen for precision shooting.

And this rifle is precise! Following is the very first group shot at 300 yards after zeroing at 200 yards. Using my preferred handload with Lapua brass and 250gr Lapua Scenars this 5-shot group is right about 0.6MOA.

As shown the rifle weighs over 17 pounds, so it makes shooting the heavy .338LM quite tolerable. After several years of delays Barrett is just now bringing caliber conversion kits to market for $1500, allowing owners to switch bolt, barrel, and mags to shoot lighter, cheaper .308 or .300WM from the same gun.

The only shortcoming as delivered is that the bolt knob is a cheap piece of injection-molded plastic. Presumably it is meant, like that standard grip, to be replaced by the end user with his preferred bolt handle.

In 2008 the US Special Operations Command (SOCOM) began soliciting a new “Precision Sniper Rifle” (PSR) to fill the gap between the .308 M24 and .300WM M2010 (both manufactured by Remington) and the M82/M107 .50BMG rifles (by Barrett). The primary cartridge for the PSR is the .338 Lapua Magnum.

A unique objective of the PSR program was to procure a system that would allow for rapid barrel changes in the field, including conversion to fire the smaller .300WM and .308 calibers using the same chassis and optic. The precision specification was already quite demanding — a consistent vertical spread of no more than 1MOA over a statistically significant number of trials. Constructing a system in which a barrel could be removed from the action in the field and then returned to the same zero may have previously be unthinkable.

It turns out plenty of civilian shooters were just as interested in owning a multi-caliber precision rifle. Shown here are three that were designed for the PSR program and made available for sale to the civilian market.

On top is the Barrett MRAD. Initially offered only in .338LM for $6000, Barrett just brought its $1500 conversion kits (bolts, barrels, and magazines) to the market.

In the middle is Accuracy International’s PSR, currently sold only as a complete kit with all three calibers for $17000.

Bottom is the bullpup Desert Tactical Arms SRS, the bargain of the group at $3000 for the chassis and roughly $1500 per caliber kit. We previously reviewed the DTA SRS. Of the multi-caliber PSRs it currently seems to have the greatest market penetration. It is also available in the widest array of calibers, and even has third parties manufacturing conversion barrels.

The PSR contract was finally awarded this March to Remington’s “Modular Sniper Rifle,” which will probably not be available for civilian purchase until government demand has been satisfied.

The LaRue OBR represents the pinnacle of autoloading medium-caliber rifles. It’s not the only premium AR-10-pattern gun on the market, but it’s probably the best deal. The base rifle is just over $3000 … plus a wait currently running about eight months. Fit and finish on this hand-built gun is superlative. In fact, the tolerance between the upper and lower was so tight I had to use a rubber mallet to separate them at the rear takedown pin.

The 18″ .308 caliber model here has been kitted up with LaRue’s quick-detach scope mount ($264), a $2200 Nightforce F1 NXS scope, Atlas QD bipod ($280), and $1250 Thunder Beast 30BA suppressor. Suppressor compatibility is one of the great features of this gun: It has a port selector on the gas block that toggles to the right to reduce blowback when shooting with a suppressor. And, since even that won’t prevent carbon fouling of the action, most of the BCG has a polished chrome finish that wipes clean — shown here cleaned after its first extended range session:

The rifle comes with two of LaRue’s M110 20-round magazines, which are slicked-up boxes with a fully-welded seam in the rear to maximize loadable cartridge length. Additional LaRue mags run $75/apiece.

A couple of sons joined us for the rifle’s inauguration. After we sighted in at 200 yards a 90-pound 12-year-old with little experience was able to get behind it and ring two 10-inch swinging plates, alternating back and forth with no hesitation, for a full magazine. It was an impressive feat. Before moving to more distant steel I jumped on it and took the first four shots at 300 yards with my 150gr handload optimized for 18″ barrels:

With both 168gr FGMM and this handload the rifle is easily a 1/2 MOA gun. Update: Further testing at 100 yards using state-of-the-art statistics show its CEP is under 0.4MOA.

The trigger is a crisp Geissele SSA two-stage, with about two pounds on each stage. When given the choice I opt for single-stage triggers, but on a rifle designed for the most grueling field conditions I can agree that a two-stage offers an extra layer of control while still allowing for the precision of a light pull.

After I bought a Noveske upper I decided it deserved its own lower, and in order to get exactly what I wanted I chose to build this one myself. The finished lower shown above started out as this $700 collection of parts:

Going roughly clockwise from the bottom these are:

• $100 Double Star stripped lower + $25 dealer transfer fee
• $20 Magpul MOE+ grip
• $240 Magpul UBR stock
• $160 Timney 667S 3.5lb single-stage trigger
• $125 JPSCS-15 Silent Spring System
• $20 Brownells lower parts kit
• $16 Troy Enhanced Trigger Guard

The actual assembly took me perhaps two hours, and that’s without any special tools that can make inserting some of those springs and pins a lot easier. There are several decent online guides for the process.

The stripped lower is the only serialized part, and so the only thing that has to be purchased through a licensed gun dealer. (It’s kind of funny doing the paperwork to buy a “rifle” and walking out with nothing but a small block of metal.) I was lucky to have ordered this lower last November just before the double-bubble in demand that is only now subsiding. The brand doesn’t really matter: A standard AR-15 lower is machined from forged aluminum and is hard anodized black. There are only a few variations that one needs to be aware of to ensure parts compatibility: trigger pin and buffer tube size (military or commercial), and safety throw (standard or short).

The biggest splurge on this lower is the UBR stock: It’s Magpul’s top-of-the-line telescoping stock, and unlike any other it is rock solid with zero movement or rattle at any extension. I also paid up for the JP Enterprises Silent recoil spring system because I was building this lower for an often-suppressed upper, and even when I shoot unsuppressed I usually wear electronic ear muffs. I find the rasping, twanging noise that accompanies many AR-15 recoil springs’ cycles annoying. Not all of them make it — for some reason the spring on my SR-556 is silent — but I didn’t want to leave this one to luck. The other advantage of the self-contained JP system is that it doesn’t require a retainer detent: I omitted that from the receiver so the one-piece buffer/spring assembly can easily be installed and removed.

I’m a stickler for triggers — a light, crisp trigger is essential to wringing all of the accuracy potential out of a gun. I have and like a Chip McCormick drop-in, but I prefer the retention mechanism on this otherwise functionally indistinguishable Timney unit: The CMC trigger requires special pins that secure with external C-clips. The Timney uses the standard trigger-group pins and is retained by tightening screws that press the body up against the pins.

There is a diverse market in grips for AR-15s. Since I have large hands I go for larger grips. I also stick to grips with an integral backstrap to avoid any pinching in the otherwise exposed joint between the grip and the receiver’s back radius where the firing hand web anchors itself. I like the tacky rubber on my Hogue grip, but it doesn’t have a backstrap and, like comparable Ergo grips I have tried, its core has some flexibility that I don’t want when I have to move the rifle by the grip. The MOE+ delivers that soft rubber finish with the rigidity I was looking for. I would like it more if it had the stippled style of the Hogue instead of the front and rear grooves that work better on hard plastic.

Pictured here is an AR-15 with a $1150 Noveske Rogue Hunter Upper chambered in 300 BLK. I bought the upper from a friend the first time we took it to the range. He didn’t think it justified adding another caliber to his collection; I fell in love with it. It has a pistol-length (very short) gas tube so it reliably cycles any load, even without a suppressor. It has a stunning stainless steel barrel with 1:7 polygonal rifling, sheathed in Noveske’s NSR KeyMod handguard. After years of work with piston rifles I guess I had forgotten the virtues of DI guns: This is so light, so accurate and, with a suppressor shooting subsonic rounds, so quiet!

My first review of an AR-15 criticized its direct gas impingement (DI) action for causing unnecessary fouling and heating in the receiver. Since I like to keep guns in mint condition, scrubbing and scraping baked-on carbon fouling from the action after every range trip became a dealbreaker: That AR-15 is one of the few guns I have ever sold as I moved my collection of autoloading rifles to what I considered to be superior piston-based actions. I have since realized the situation isn’t so simple.

One technical clarification is in order: The standard AR-15 action is not really “direct impingement.” Eugene Stoner took pains to clarify that in his patent on it, characterizing it instead as a gas piston system with the operating rod cleverly replaced by an expansion chamber on the bolt carrier itself. Nevertheless, to aid discussion and follow tradition I will continue to refer to the Stoner action as “direct impingement” (DI) and reserve “piston” for actions with op rods.

After years of testing piston rifles with suppressors I have learned that no matter how you restrict the gas flow on a conventional autoloader you can’t keep fouling out of the receiver. Suppressors hold more backpressure over a much longer period than an open muzzle, which results in a lot more blowback through the chamber when the action unlocks and ejects the fired case. You can actually see the blowback out of the ejection port in this remarkable photo by Oleg Volk:

You can also see evidence of the difference on these .308 cases:

The ones on the left were shot without a suppressor, and the ones on the right with a suppressor. The same carbon you can see covering those cases fills the receiver, fouling it as badly as a DI action.

Piston guns still retain their other fundamental advantage over DI guns, which is that the action stays cool (though the forward piston blocks get scaldingly hot). But as I noted in my last post, advanced coatings can also help to make either easier to clean.