August 28, 2019
Photos by Mark Fingar
The concept of having one rifle that does everything is not new, but it is a hard concept to realize. There’s a balancing act that occurs and it pits durability against weight against cartridge selection. Historically this means the larger the cartridge, the larger the rifle that shoots it, and the lighter the rifle, the less abuse it can take.
These old ideas are losing their relevance in the face of modern-design rifle manufacturing and materials selection. Patriot Ordnance Factory’s (POF) newest rifle, the Revolution DI (“DI” stands for “direct impingement”), is a prime example of what happens when a manufacturer takes the time and puts in the effort to create the smallest, lightest and most durable AR-pattern, large-frame carbine available.
AR-15 Parts in a .308?
The Revolution DI is a carbine offered in .308 Winchester and 6.5 Creedmoor chambers. Most notably, it is the same size and weight as an AR-15 in 5.56 NATO, a goal of multiple AR manufacturers for some time. No one has achieved it quite like POF-USA. The most impressive aspect of this fascinating design? The bolt carrier group.
On receiving the Revolution DI for testing, I separated the upper and lower receivers and removed the bolt carrier group for inspection. I knew what to expect, but was still surprised at its diminutive size. It looked suspiciously like the bolt-carrier assembly from an AR-15, so I tried to put it in one. It fit. Well, it fit right up until the Revolution DI’s bolt ran into the back of the AR-15 barrel extension. When POF says this rifle is a .308 that’s the size of an AR-15, it’s true!
Next, I threw the Revolution DI bolt carrier group on a scale and compared its weight to a regular AR-15 carrier assembly. The DI’s is 1 ounce lighter. While this is an exciting development, it could also be a cause for concern. Having an AR-15’s bolt carrier group with such light reciprocating mass in a .308-chambered rifle could easily cause it to cycle so fast that the bolt carrier group runs faster than the magazine can feed it. This situation could also cause more recoil. After a session at the range, my concerns about recoil and excessive bolt speed were put to rest.
I also noticed a unique feature about POF’s bolt carrier group that greatly slows the cycle time of the entire assembly. POF shortened the carrier’s gas key that sits on top of the carrier. Normally there are two bolts that hold a carrier key in place. On POF’s shortened design, there is only one. Shortening the gas key allows the carrier to cycle deeper into the buffer tube, giving it a longer distance to cover every time the rifle fires. It buys a lot of time for the magazine. The magazine then uses that time to push the stack of ammunition up into the magazine’s feed lips where the bolt coming forward strips a round and shoves it into the chamber.
Bolt & Extension
The bolt and barrel extension — where the bolt locks close behind the chamber — required serious design effort by POF. The one issue there is no getting around is the size difference between a .308 Win. cartridge and the 5.56 NATO/.223 Remington cartridge. Trying to stuff the .308 Win. cartridge into a .223-diameter barrel extension is much harder than it sounds. The two biggest hurdles are the additional width of the .308 Win. magazines and the larger bolt-face diameter required to fit around the case head.
Close examination of the Revolution DI’s bolt showed that the bolt lugs are shorter and the overall diameter is slightly larger than a regular AR-15 bolt. The slight increase in overall diameter is necessary to fit the .308’s case head. The bolt lugs, while shorter, are much stronger than what’s found on a bolt made from traditional military specification (mil-spec) materials.
The materials POF uses for its bolt and extractor are far more exotic than what’s normally used to manufacture these parts. Reducing size while increasing strength requires materials that are more expensive. They take a lot of time and money to test.
I spoke with Frank DeSomma, owner of POF-USA, about the Revolution DI and he was hesitant to share the materials he was using to create the bolt and extractor. I can’t say that I blame him. There are a handful of AR-pattern rifles that feature bolts fabricated from exotic alloys. These bolts usually cost around $300 (for just the bolt) and no one wants to reveal the exact alloy. While AR bolts have been made from Carpenter 158 and 9310 for years, there are much better materials available and that’s what’s found in the Revolution DI.
DeSomma did say that he conducted extensive destructive testing on the rifle and is extremely confident in its durability. Destructive tests at a metal lab took the bolt material to -110 degrees Fahrenheit, a temperature so cold many steel types become brittle and shatter under the stress. (Mil-spec-only tests between room temperture to -40 degrees, i.e., “the Sharpie Test.”)
POF also fired thousands of rounds of Wolf steel-cased ammo during their testing. It burns dirtier than most, and the steel cases, when used in large quantities, are hard on chambers.
The final bit of testing included full-auto fire. POF is one of the very few manufacturers that tests their .308 rifles in full-auto. This is some of the most abusive testing possible because heat builds up quickly; Every time a .308 Win. cartridge fires, it burns almost twice the powder of a .223 Rem. case. Burning that much powder that quickly rapidly heats up the rifle; Heat and pressure are what destroys any rifle, but these would have exposed any flaws in the Revolution DI design.
One Size Does Not Fit All
The Revolution DI has a much softer recoil than you’d expect thanks to the reduced reciprocating mass and longer cycle stroke. It’s still a .308 Win. rifle that weighs 6.8 pounds, and there is slightly more recoil than a .223 Rem. However, the longer and adjustable POF DIctator gas system provides additional insurance that the rifle will function reliably without the heavy internals. The adjustable gas system also reduces recoil.
The DI features POF’s nine-position adjustable DIctator gas block. When it comes to a .308 Win., an adjustable gas block is required whenever there is the potential for suppressor use. It is also very convenient to have considering bullet weights for the .308 Win. vary from 110 to 185 grains.
I spent some time adjusting the DIctator gas block and quickly grew to admire its design. The block is accessible just in front of the company’s 14½-inch Renegade handguard, and the provided wrench makes the dial even easier to tune. The way to adjust any gas block is by turning down the gas until the bolt fails to lock back onto the empty magazine. (Loading and firing only one round in a magazine is a great way to decrease ammo consumption during this process.) Next, open the gas block up one click at a time until the bolt locks back. Then add one click to be safe and you’re done. The whole Revolution DI gas block adjustment took me between two and three minutes.
POF installed a rifle-length gas system on our 16½-inch-barreled test rifle chambered in .308 Win. This is the longest possible gas system for that barrel length, and it gives residual chamber pressure the most time to drop, further decreasing the binding force on the bolt lugs. This is great for component life and reduces the violence with which the rifle extracts and cycles. Between the improved BCG and the long gas system, the Revolution DI only requires a standard carbine buffer to round out the system.
The Revolution DI also has all the features POF-USA has become famous for: the e2 chamber, enhanced extractor, roller cam pin, heat-sink barrel nut and a completely ambidextrous lower receiver. Each of these are unique to POF-USA and the result of extensive development and testing.
The roller cam pin features a rotating pin head that spins in the upper receiver instead of chewing a gouge in the side of the upper receiver. This innovation greatly reduces the stress imparted on the cam pin and extends its life.
The chamber throat is the area most vulnerable to heat, and POF’s barrel nut does a good job of pulling heat away from it. The large aluminum barrel nut is thick and finned to push as much heat away from the chamber as possible. The mass and fins on the nut absorb and dissipate heat rapidly.
POF’s ambidextrous lower receiver allows for complete functionality of the bolt catch, bolt release and magazine release for either left- or right-handed shooters. It’s not uncommon to find ambidextrous AR lower receivers, but models that allow a left-handed shooter to lock the bolt to the rear without taking his firing hand off the pistol grip are hard to find. POF’s receiver has this capability.
There is a lot of technology and sophisticated design in the Revolution DI from POF-USA. Engineering an AR-15 bolt carrier for a rifle chambered in .308 Win. or 6.5 Creedmoor is no easy task, but the size and weight reduction from doing so benefits all AR-pattern rifle shooters.
POF REVOLUTION DI SPECIFICATIONSType
: Direct impingement, semiautomaticCaliber
: 7.62 NATOCapacity
: 10, 20 rds.Barrel
: 16.5 in., POF e2
: 34 in. (collapsed), 38 in. (extended)Weight
: 6 lbs., 13 oz. (tested)Stock
: MFT, adjustableGrip
: MFTLength of Pull
: 11.5 in. (collapsed); 15.5 in. (extended)Finish
: Type III, hardcoat anodizedSights
: POF Drop-In Trigger System; 4 lbs., 8 oz. (tested)Safety
: Two-position selectorMSRP
: POF-USA, 623-561-9572, pof-usa.com
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