7.62×40 WT

posted on November 10, 2011

Some things in life are so obvious they get overlooked for a long time. That's the case—no pun intended—with the 7.62x40 WT cartridge, a .223 Rem. case necked up to .308 Win. Original work on this cartridge was done by Kurt Buchert, who called it the 7.62x40 USA. With Buchert's blessing, Bill Wilson of Wilson Combat took the concept and made it a functional reality.

Why? We'll get to that. Folks have been trying to put bigger bullets and more power into an AR-15 for a long time for both military and sporting purposes. Examples include the 6.5 Grendel, the 6.8 Rem. SPC and the big, shoulder-smacking .450 Bushmaster. None have seen big-time success, but all have cult-like followings among users who believe they're the answer to all things ballistic. Admittedly, I dote over the .30 Rem. AR, which I find to be the most powerful and ballistically balanced cartridge you can fire from an AR-platform rifle.

One problem is all these cartridges require not just a new barrel, but also a new bolt, possibly a new buffer and buffer spring, a new magazine and in some cases, even a new upper receiver. This makes conversions more costly and less appealing. With the 7.62x40 WT, all you need is a new barrel and a Wilson Combat-modified Lancer L5 AWM 5.56 magazine (though some unmodified AR-15 magazines will work). Ballistically, it converts your AR-15 into a flatter-shooting .30-30 Win., which sort of answers the "why" question.

Wilson began developing the 7.62x40 WT after studying the ballistics offered by the .300 AAC Blackout. He wanted a cartridge that would give optimum supersonic performance with lighter .30-caliber bullets, instead of the 220-grain projectiles for which the .300 AAC Blackout was designed.

"After experimenting with the .300 Blackout, I concluded the cartridge case really needed to be 39 to 40 mm long to work properly with common 110- to 125-grain, .30-caliber bullets," said Wilson. (The .300 AAC Blackout case is about 35 mm long.) "Don't take me wrong, I'm not anti-.300 Blackout. I just firmly believe it's a subsonic-only cartridge."

Wilson established his reputation by building superb custom 1911 pistols, but Wilson Combat also makes wonderful ARs. He is not just a competitive shooter with a tactical mindset; he is also an avid hunter. At present, Wilson may be doing more to help solve the feral hog problem in Texas using an AR-15 than anyone.

He discovered 125-grain Sierra Pro-Hunter and 125-grain Nosler Ballistic Tip bullets actually performed more like controlled-expansion bullets at 7.62x40 WT impact velocities. After guiding hunters to more than 60 hog kills, Wilson believes, "With the same shot placement, the 7.62x40 WT works about like a 6.8 SPC and runs cleaner than it or the .30 Rem. AR when suppressed."

Based on 7.62x40 WT testing I conducted using Wilson Combat ammunition, 125-grain bullets leave a 16-inch barrel at around 2,400 fps and a 20-inch barrel at 2,500 fps. This equates to velocities high enough to generate bullet expansion at 250 yards. If zeroed 1.5 inches high at 100 yards, drop at 250 yards is less than 10 inches. These are great short-range ballistics—perfect for hunting or a utility/survival rifle. With the wide variety of available .30-caliber bullet options, moderate-range tactical applications are virtually endless.

Granted, the ballistics are similar to the Soviet 7.62x39 mm cartridge used in AK-platform rifles. However, converting an AR to the Russian cartridge requires a new barrel, bolt and magazine. What's more, that particular cartridge has a dismal history of poor reliability in AR-platform rifles. Additionally, since factory 7.62x39 mm ammunition is loaded with bullets having diameters between 0.308 inch and the original spec of 0.311 inch, accuracy can be less than inspiring.

Wilson Combat offers complete rifles, upper receivers, barrels and five different factory loads for the 7.62x40 WT, but it's unclear whether others will follow suit. Given the usefulness of this cartridge, it wouldn't surprise me if more AR manufacturers got on board, and Wilson expects no royalties to follow his lead.

Ammunition availability is the risk with any new cartridge—demand drives the train. The good news is, unlike some other new cartridges, 7.62x40 WT brass is easily made from .223 Rem. cases.

The 7.62x40 WT has become Wilson's go-to cartridge at the ranch, but of course some folks will never get the concept. Despite what one unenthusiastic blogger has said about the round, an AR chambered for the 7.62x40 WT is lighter, more powerful, flatter shooting, harder hitting and infinitely more versatile than a .30-30 Win. lever action, whether you are hunting or fighting. It's also a great youth deer rifle or police patrol rifle.

There's no doubt the AR is America's favorite rifle. Wilson Combat just made it more useful and, dare I say, better.


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