7.62 X 40 WT

[PA Patrick]

I just read an article about using the 5.56 AR platform ,change the barrel, and you can now shoot .30 cal from a 5.56 case. It is called Wilson Tactical 7.62x40. With all the polymer AR components out there, can they handle this? Curious to hear others thoughts on this.

 

[Unclenick]

The polymers do not contain the pressures; the barrel and bolt do. That is why there is an AR 10 design for .308, and why the AAC Blackout (7.62×35) (shortened and necked-up .223) for subsonic loads for suppressed AR's can exist, as well as AR's chambered in 7.62×39. I'm not familiar with the 7.62×40, but unless it is substantially different in performance from the 7.62×39, or uses standard AR magazines, or has some other advantage, I would go for the 7.62×39 because of ammunition availability.

 

[mapsjanhere]

Looks like it's a 300 Blk with 200 ft/s more velocity
http://wilsoncombat.com/new/762x40-project.asp
The difference to the 7.62x39 is marginal

 

[Unclenick]

Yes. Thanks for linking that in. Seems like the Blackout without shortening the case as much. The .223/5.56 neck is 5 mm long, so what the 7.62×40 does is include part of the expanded shoulder in the finished neck rather than remove it all, as the Blackout does. That's going to mean thinner brass near the mouth of the 7.62×40 neck than is in the Blackout, but they must must have found that acceptable, as it's only the last 0.127" of neck.

It appears from the article that it does, indeed, use the same magazines, as long as you don't fill them all the way and give the springs too much bullet weight to lift. Obviously uses the same bolt, so the barrel is all that has to be changed. It probably has a reduced gas port diameter to allow for the extra barrel time under pressure.

Patrick, you've got an interesting project there. Please let us know how it turns out.

 

[skizzums]

I like the idea of the x40. if I had known about it when I did my 300, I might have went that route, but I like the 300 since just about everyone makes barrels and dies. if I was wanting a 30cal AR for hunting in a short barrel, I think it's great, but your getting close to a .308 and kind of losing the whole idea of sub-sonics. AR308's are pretty cheap now-a-days, probably cheaper than an x40 barrel and an AR host, then comes the proprietary dies and so on.