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6mm x 223 AI

Hawkshaw
Yesterday, while fiddling around on the computer, I came across a cartridge for the AR-15 which was the .223 necked up to 6mm, and shoulder blown out to 40 degrees. Looked like an ACK. IMP. Apparently all that was needed was a rebarrel to 6mm, along with the new chamber. However, now I can't find it. Is it a JDJ/SSK ?
Help please. Where can I find info, and who would do the rebarrel.
THX HAWKSHAW
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Comments

7 comments

Date Votes
  • 1KYDSTR
    Don't have info on that one for you, but have you looked at the 6.5 Creedmore? Seems to be pretty popular and there are a lot of people out there doing work on them?
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  • dfletcher
    I have the 6.5 Creedmoor, albeit in a Ruger 77V - excellent cartridge in an under rated target rifle. The 6.5 Creedmoor won't fit in an AR15 platform of course but in AR10 type would do fine. The 6.5 Grendel is all the rage in the AR15 - maybe that's what was seen - or maybe the 6X45/223 - that's supposedly getting popular.

    I have a 6X47/222 Rem Mag barrel for my T/C Encore and it's an accurate, polite cartridge.
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  • nononsense
    Hawkshaw,

    "The 6T/CU is practically identical to the older 6mm-223 Remington, also called 6X45mm that was developed in 1965. Initially the 6T/CU had been intended primarily as a metallic silhouette pistol cartridge, whereas the 6mm-223 Remington was developed as a rifle cartridge for benchrest and varmint shooting. The T/CU also differs because the cases have to fireformed to fit the chamber before load development can begin. This will create the sharp 40-degree shoulder with nearly straight case walls. The formed round will look very much like those created by Parker O. Ackley back in the 1950's when he would take a case and increase the shoulder angle then virtually eliminate all body taper. This allowed an increase in case capacity as well as velocity. These cases have simply been termed "Ackley Improved." The 6X45 only requires the handloader to run cases through the sizing die to expand the neck; shoulder angle and body taper remain the same."

    6tcu.jpg


    Best.
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  • Mobuck
    If I were looking at one of these for the AR, I'd stick with the old 6x45(6mm/223). My reasoning is feeding and extraction might be problematic with the straight bodied,sharp shouldered case. My understanding of the design was that the straight body gripped the chamber tightly lessening the thrust on the breachface of the TC. If this grip effect is still present at the time of initial extraction, something will break. Not an issue with single shot or bolt action but definitely possible with the AR.
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  • tsr1965
    Hawkshaw,

    Perhaps you need to take a peek at this link. Is this the 6mm cartridge you were drooling about?

    http://www.dtechsuperstore.com/new_altcal.htm

    Best
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  • armilite
    I had a 6X45 years ago it was an upgrade of the .223 but when the 6.8 Remington SPC was introduced some 4 years ago the 6x45 in my eyes was no longer needed in my battery at least.
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  • bentley47
    I have two varmint ARs in 223 Ackley, used for high volume prairie dog shooting. The Ackley case feeds, fires, extracts, cycles perfectly in the AR. True, the straight sidewall design grabs the chamber better, puts less recoil on the bolt, etc., but the AR bolt is activated by gas, so it cycles fine. I do add a carrier weight and extra power recoil spring to slow down unlocking, but it cycles fine with standard carrier and recoil spring.
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