Our readers, and most US gun owners in general, love their ARs. I also think that we would all agree that the .223 cartridge is insufficient for medium sized game such as deer and hogs. While scaling up to a .308 sized AR in .243, 7mm-08 or .308, certainly solves the cartridge issue; it is also associated with a much bulkier rifle. The Remington R15 in 30-AR does give shooters the ability to have a gun that carries like a .223 and hits with a .30 caliber cartridge, but does this at the expense of a proprietary bolt, magazine and cartridge.
Enter the 7.62x40WT. Based off the 7.62x40mm wildcat, the 7.62x40WT is based off 5.56x45mm parent case trimmed to 1.560″ and then re-sized to accept 30-caliber bullets. With factory offering from 110-125 grains, this cartridge seems to be the perfect hunting upgrade for the AR enthusiast. The only part of a 7.62x40WT rifle that is different from a standard .223 AR is the barrel. That’s it.
Since all of the other parts are common, we ordered an 18″ stainless steel non-threaded crowned barrel from Wilson Combat configured for a mid length gas system. In addition to the barrel, we also ordered a low profile gas block and mid length gas tube. 7.62x40WT barrels are available in 11.3, 14.7, 16, 18 and 20″ lengths with both carbine and mid length gas systems. This allows the end user to order a barrel to suit his needs and use parts he has on hand, rather then buying a complete upper. For the price of the barrel and a couple boxes of ammunition, you can convert your favorite AR into a hunting rifle during the season and convert it back when you are done. Genius.
With a 1:12″ twist, our 18″ barrel was a work of art. The barrel itself was bead blasted stainless, with “Wilson Combat 7.62x40WT 1-12″ engraved on the bottom. 180-degrees beneath the gas port, a recess was drilled to provide a secure hold and proper index for the gas block. The barrel extensions was beautifully polished stainless steel, with proper M4 ramps.
We enthusiastically grabbed an extra A4 upper and traditional 12″ aluminum free float tube and began building a truly modern hunting rifle. This “franken rifle”, assembled from a menagerie of parts, was equipped with an A2 stock and Leupold Mark 4 3.5-10x40mm M1 TMR scope in GG&G mount. We were a little skeptical about how accurate our rig would be, so we headed to the range to find out. The aluminum tube free float forearm and A2 stock were also found on the R15 30AR we reviewed, however, this rifle’s 18″ barrel was a full 4″ shorter, making it easier to handle.
All rounds were fired from a concrete bench with an adjustable front rest and rear bag. Using a laser boresighter at fifty yards we managed to have our first round hit our 1 1/4″ boresight dot. A good start.
Making an elevation adjustment, and moving the target to 100 yards we fired a series of groups with the 125 BT and 110 TTSX loads provided by Wilson Combat. Range conditions were 91F with 84% humidity and gusty 15-20 mph no value winds. The 125 BT had an average group size of .815″ and the 110 TTSX .859″. Impressive performance for a franken rifle, demonstrating the value of a quality barrel and ammunition.
While the rifle recoils slightly more then a 223 variant, recoil was negligible. Most interesting, was how cool the barrel remained. We fired nearly four boxes of ammunition in short order on a hot day and accuracy did NOT degrade and did not feel particularly hot to the touch. We used a vintage aluminum follower, surplus Colt magazine that fed the 7.62×40 well.
Velocity data was obtained using a MagnetoSpeed VI Barrel Mounted Ballistic Chronograph. Using magnetic sensors to pick up the fired round, instead of light like traditional chronographs; the MagnetoSpeed doesn’t require an elaborate set up. The user simply attaches a bayonet style sensor to his barrel and attaches the cable from it to the display unit.
Five rounds were fired of each cartridge type to determine average muzzle velocity. The 125 grain Nosler Ballistic Tip load clocked in at 2325 FPS with a standard deviation of 5, and the 110 Barnes TTSX 2447 FPS with a standard deviation of 10. Complete external ballistics for the 125 grain load from our test rifle can be found here WT7.62X40.