10mm AR cartridge

[Texas by God]

It seems to me that the 6.8 SPC brass could be blown out straight to 10mm for another thumper AR15 cartridge.
Has anyone done this?

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[Moleman-]

Here's one https://mdws.forumchitchat.com/post/...6954?&trail=25

[DougGuy]

It seems to me that the 6.8 SPC brass could be blown out straight to 10mm for another thumper AR15 cartridge.
Has anyone done this?

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I too was thinking about a straight walled AR case, whatever caliber it came out to be, 40 or so?

But, like I mentioned in the other AR thread, now we are down to pistol bullet ballistics and trajectory but with rifle type velocities and pressures.

[RU shooter]

I remember hearing about some being built to fire 10mm mag might have been one of the AR wildcat sites case length is 1.255

[Texas by God]

Thanks for the replies. What would the 7.62 x39 yield as a straight case caliber wise?

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[RU shooter]

Thanks for the replies. What would the 7.62 x39 yield as a straight case caliber wise?

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Base dia is .443 depends how much case taper you want ? Figure .400 plus neck thickness would be .420-.424 ish

[Loudenboomer]

A straight walled 6.8 spc - 10mm may work well in the 336 Marlin also!

[357Mag]

Texas -

Howdy !

FWIW -

Remington brand .35 Remington brass has an inside diam of .40 cal from the shoulder juncture, all the way down to .125" above the case' web.

.35 Rem base diam is perhaps too large for sensible use in an AR ?


With regards,
357Mag

[Texas by God]

I guess the rim could be turned down if need be to work. Something like the .450 BM, but using easier to get 6.8 parent brass. Just like the link shows. All it takes is money we live in the best country!

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[Baltimoreed]

Get a pistol caliber ar upper chambered in 40S&W, have the chamber deepened to what your wildcat would need. You might be able to use .450 mags. You would probably have to tinker with buffer weights and springs. I’ve built 4 .45 acp ARs but they are all blowback, I don’t know about the .40 so I don’t know about the gas system you would need. Good luck.

[Moleman-]

You're going to have to run locked breech in order to get the most of of the cartridge. I've seen some custom DI 40 uppers out there over the years, but if you're going to pay the initial money for a custom barrel have one made as a 40x?" from the get-go. A cu$tom 40S&W DI upper is going to have a very short gas system for the lower pressure and short pressure curve and would need to be chambered again and a new longer gas system installed. If you've got access to a lathe, have Manson reamers make you a reamer, get a blank and a tromix big bore extension. I'd bet though that if there were enough of a demand that either BIGGDAWG or MDWS that will make a run of those barrels.

[beechbum444]

Not trying to rain on anyone's ideas....been tinkering with this one for a while....then I ran across the 400 AR cartridge .......following thread closely

[Baltimoreed]

You are right there moleman, the .40 will be a blow back too which won’t work on a rifle cal. You could contact Rudy Koester at Macon Armoury and see what he’s building nowadays. He makes a very nice DI .45, last shot bolt hold open too. He’s been trying to talk me into one for years. A very talented guy. Don’t know if he’s doing a .40 ar now. But if you’ve got the disposable income he would help you dispose of it.

[Moleman-]

You are right there moleman, the .40 will be a blow back too which won’t work on a rifle cal. You could contact Rudy Koester at Macon Armoury and see what he’s building nowadays. He makes a very nice DI .45, last shot bolt hold open too. He’s been trying to talk me into one for years. A very talented guy. Don’t know if he’s doing a .40 ar now. But if you’ve got the disposable income he would help you dispose of it.

Known Rudy (MadMachinist) for years, he sent me a message over the summer asking about my 357AR.

Talked with a different guy down in TX (Don Halter) with blowing out a carcano case and adding a 40 bullet 4-5 years ago or so that was similar to the 400AR. I had some 6.5 carcano brass at the time and blew out a few and gave him the measurements. He ended up going with a belted bottleneck case called the 400 KragAxe if I remember correctly. At the time 6.8 basic brass wasn't available and carcano seemed like a good choice except for the cost. First heard about the 400AR about 2 years ago and at the time was supposedly made from carcano brass. It was interesting as it was basically the same thing as what Don was trying to do. Haven't heard anything about in since then, but I also haven't looked for it. The availability of better priced 6.8 basic brass should make either a bit easier to make.

[Baltimoreed]

Attachment 233003Attachment 233002Rudy did bbl work on my first AR build, a .45acp sbr with a forward charging handle of my design and construction. Hopefully I will get by his shop this coming year on a Florida vacation and get to meet him.

[missionary5155]

Good morning
401 Winchester Brass is easily made using 7.62x39 for the Winchester model 1910. Brass ends up similar to 414 Supermag (1.6" brass) which will propel 280 grain cast to 1900 fps from a 20" Marlin 336 barrel. More if you so desire.
So figure your 1.7" blown out case will do the same plus a bit depending on barrel length.
Mike in Peru

[beechbum444]

the 401 wsl with 762 x 39 brass was the same route that I went down. It would be amazing in a lever gun