Modern Intermediate Calibers 006: The 7.62×40 Wilson Tactical

7.62x40 WT next to its parent, the 5.56mm.

7.62x40 WT next to its parent, the 5.56mm.

Like the .300 AAC Blackout that we discussed earlier, the 7.62×40 Wilson Tactical was intended to be a medium-performance .30 caliber cartridge that would function in standard AR-15 type rifles with minimal modifications, such as a barrel change. Also like the .300 AAC Blackout, the Wilson round was based on an earlier wildcat, which was designed by Ken Buchert and also called the 7.62×40. Unlike the .300 Blackout, however, the 7.62x40mm Wilson Tactical sacrificed some versatility for raw power in the form of a lengthened case based on the 5.56mm case, instead of the .221 Remington Fireball used by the Whisper/Blackout. This longer case gives the 7.62×40 WT a significant performance advantage over the .300 Blackout from comparable barrel lengths, but it limits how ballistically efficient the projectiles used by the round can be. In theory, the 7.62×40 WT can also be loaded with subsonics, like the .300 AAC Blackout, although the short ogive length limits which COTS bullets can be used for this, and no factory subsonic ammunition exists for the Wilson round. This makes the 7.62×40 WT virtually a dedicated supersonic hunting or 3-Gun round (in which it makes Major Power Factor), but it is still worth considering in our discussion. Now, on to the ballistics:

 

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In terms of weight, the 7.62×40 WT is slightly heavier than the .300 AAC Blackout with comparable bullet weights. My 110gr Sierra HP round weighs 14.5 grams (224 grains), while a 125gr load would weigh about a gram heavier than that.

Note: All ballistic calculations are done with JBM’s Trajectory calculator, using the ballistic coefficient appropriate to the projectile being modeled, and assuming an AR-15 as a firing platform. Also, keep in mind that there is no single true velocity for a given round; velocity can vary due to a large number of factors, including ambient temperature and chamber dimensions. Instead, I try to use nominal velocity figures that are representative of the capability of the round in question.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Wolfgar

    I like this round for close range deer hunting but it does have significant more recoil compared to my 6.5 Grendel. It is a hard hitting round which I would compare to the 7.62X45 Czechoslovakia round. Modified Lancer mags are also available from Wilson which feed very reliably.

  • penguin

    If you are including both 7.62x40WT and .300BO in this series, you might also include .277 WLV (6.8×39) alongside the 6.8 SPC. Ballistics are very close, but there’s a bigger difference in weight between the two rounds. And there’s a lot more “factory” loads, both super and subsonic, for 277 WLV than for the 7.62×40.

    • Anonymoose

      I don’t know why he included this. Is .450 Bushmaster (the redheaded stepchild of .458 SOCOM and .50 Beowulf) next?

      • No, I am not going to tackle big bore rounds. I wanted to represent the maximum possible performance of a .30 caliber round from a 5.56mm case head, which is something I plan to reincorporate later.

        Plus, I had one of the rounds available and the ballistics were very straightforward, so why not?

        • Robert w

          Personally, as a 3-gun shooter, I find the WT to be a an excellent example of min-maxing, just like how the 9×23 was for USPSA open. The question is will 3-gun go the same route and lower PF to allow 300blk, definitely a more popular round, to become the new major power factor. The other option is to raise the PF to something truly unobtainable with a small frame AR.

      • To be fair, the original .45 Professional wildcat is older than the .458 SOCOM or .50 Beowulf.

    • Sunshine_Shooter

      If there is a more obscure, non-wildcat cartridge for the AR platform, I haven’t seen it. Nathaniel might as well include .30 Remington AR and .17 Remington in this series.

      • All three rounds were already on my list of “possibles”.

        • ostiariusalpha

          The microcalibers loaded in 5.56mm case head cartridges have a fascinating history. As many people as have put forward 6.5 & 6.8 calibers as replacements for the 5.56 NATO, nearly as many have suggested sub-5mm bullets as viable candidates.

        • Sunshine_Shooter

          I think the next calibers you do should be .17 Rem, .277 Wolverine, and .204 Ruger. The .204 is commercially available, the .277 is a faster .300BLK, and the .17 Rem is just an awesome round.

          It’s your series, so you do you.

        • toms

          Do a 5.56x43mm review. Its a badass intermediate based on the 6.8 necked down to .224. 77gr tmk at 3050fps is an awsome do all 800 yard round.

          • Looked it up, it’s called the “.22 PDK” and it’s is pretty interesting.

        • Fox Hunter

          Do a review on the old intermediate cartridges too, like .25 remington, 6.5×50,

        • Adam D.

          Have you thought about the 6.5x40mm?
          For me as a ballistics layman, purely from a “guts-feeling” standpoint, it seems like the most interesting does-it-all wildcat for ARs.

      • penguin

        277 WLV is hardly more obscure than 7.62x40WT. Neither is SAAMI accepted, neither is as nearly known as 300BO or 5.56 or 6.8SPC, but both have their own small followings that you’d miss if you weren’t looking for them. For each caliber, you can really only buy barrels from one source (unless you custom order from one of at least three manufacturers in the 277 WLV’s case). Both calibers have only one or two places to buy loaded ammo from, with 5 or so different loadings available for each, for similar prices.

        If Nathaniel is including both 300BO (popular, esp. for subsonics) and 7.62x40WT (obscure, good for supers) as examples of remarkably-similar-but-differring-niche-roles on 30cal intermediate cartridges, then it makes sense to include the 6.8SPC (popular, hunting with supersonics) and the 277 WLV (obscure, better for subs and/or standard AR-15 parts) as examples of 6.8cal intermediate cartridges, with similar performance but different niches.

        Clearly there’s more going on in Nathaniel’s head than just a straight ballistic comparison, or such similar rounds as 300BO and x40WT wouldn’t both be on the list together, much less on the same list at 7.62×39.

    • JoelC

      Agreed, although I wish more manufacturers had heavy 6.8mm bullets for subsonic applications. That is the major advantage of the .308 cal.

    • Fox Hunter

      Dont forget the 7mm Raptor.

  • Sunshine_Shooter

    I think my reading comprehension is lacking this morning. I understand that it is not interchangeable with .300BLK, but did the article say why? It mentioned ogive lengths, but I thought those were projectile dimensions, not case dimensions.

    • penguin

      Since the case is longer (300BO is 35mm, x40 is 40mm), taking up more room in the magazine and forcing the use of shorter-ogive bullets, to keep from having to seat the ogive inside the case mouth in order to fit in the magazine.

      • penguin

        Bad grammar, sorry. I meant to say that the x40 takes up more room in the magazine, necessitating the use of shorter-ogive bullets so you’re not seating the ogive inside the case mouth. Most of the heavy-for-caliber bullets (subsonics) have long ogives, making them unusable in an AR-15 action for the 7.62×40.

        • Sunshine_Shooter

          Thanks for the explanation. Between you & @ostiariusalpha:disqus I feel like I’m damn near an expert by now.

        • 6.5x55Swedish

          Yeah, but 300BLK seem to go more for slow and heavy than 7.62×40 so you would need heavier bullets, right?

    • ostiariusalpha

      Okay, so the short answer is that the 7.62×40 WT has a shoulder that sits more forward, so it will not seat in a .300 BLK chamber. You might be able to accidentally slip a Blackout cartridge into the WT chamber though, which is something to think about if you have both rounds.

      • Sunshine_Shooter

        The pic helps a lot. It sounds like the .300BLK would be the more flexible of the two.

        • ostiariusalpha

          Oh, it definitely is.

  • JumpIf NotZero

    The three people (at Wilson) who use this round are really going to appreciate the article.

  • JoelC

    I had a lot of interest in this round until i looked at the loads. Granted I tend to load .300 BLK a little long, and therefore a little hotter, but the small performance difference didn’t seem worth the investment in a new upper. I would love to see a good 6.5mm based off the 5.56×45 case hit the market the market though.

    I’m sure a lot of people here would consider me weird though, since I prefer more options on the market than less… somehow a lever action .30-30 in 2016 just isn’t that appealing to me.

  • toms

    Wilson produced susbsonic load data for this round. All in all it does what the 300 queef out does but with a lot more on the supersonic side. It will shoot 220 SMKs subsonic easily. Its a better round but dead do to AAC’s superior marketing. It pretty easy to load for but you need to use lancer and metal mags to get the length.

  • Fox Hunter

    One advantage i see is you can load to 300 BLK velocities using similar bullet weights at lower chamber pressures, since you have more case capacity.

  • BigC

    Or you could just buy an AK!