• Myth Busted - Proof Testing an Eaton Carcano Rifle

    "Myth Busted" - Proof Testing an Eaton Carcano Rifle
    *** Testing and Analysis by Advisory Panel Member Andy ***


    I am a skeptic at heart. I do not believe everything I read, particularly when:

    a. it is based on hearsay (an old gunsmith told my friend, etc.); and
    b. it makes no sense.

    The Eaton Carcano was a Carcano sporterized between the wars by Cooey. THe action was untouched, but it was rechambered from 6.5x52 Carcano to 6.5x45 MS, had double set triggers added, and the stock was modified. Along the way, a new barrel was installed by screwing it into a stub made from the old barrel base.

    I have two complete and one Eaton Carcano parts gun, and when I bought my first, I was warned not to shoot it. Both points a. and b. applied, so I examined the gun, particularly the "dangerous" method by which the barrel was affixed, and was not convinced. Once I found a parts gun to test, I was on my way (at the other end of a long string) - doing some original research.



    Some Crude "Proof-Testing"

    The first load was a full strength load with H4895, followed by the same H4895 load plus 30%, then a case full of Unique, a fast pistol powder. 27.0 gr of Unique behind a 160gr bullet in the small 6.5mm Carcano runs pressure just a bit short of 100K psi. The barrel held, the receiver was undamaged, but the cartridge did not fare well. The pictures show the results:

    - casehead blown to bits;
    - extractor blown off the bolt; and
    - brass powder covers the bolthead.


    Pic 1 - The Barrel "Stub" into which the new barrel is affixed and widely believed to be pressed in and held by a set-screw. False, as stated above.


    (Click PIC to Enlarge)


    Pic 2 - Left to Right - barrel with tiny indent for set screw, barrel stub, set screw, receiver


    (Click PIC to Enlarge)


    Pic 3 - The Bolthead and remnants of the Casehead - note that the extractor is missing.


    (Click PIC to Enlarge)


    Pic 4 - a view into the chamber showing where the extractor (lower right) and brass bits went. You can clearly see the majority of the cartridge still in the chamber.


    (Click PIC to Enlarge)


    Pic 5 - Getting the remains of the cartridge out was not easy. As shown in picture three, the cartridge head was blown off and the "new" end was about 1/8" inside the chamber. After removal, it will now only go in about 3/4" with finger pressure, leaving over 1" outside the chamber.

    At "normal" pressures the brass expands easily to chamber size and springs back, the (steel) chamber expanding and springing back much less. At extreme pressures, both the brass and chamber expand quite a bit, and that expansion can exceed the amount that the brass can spring back causing the cartridge to lock in place to some extent and be difficult to extract.

    In this case, what's left of the cartridge is actually reverse-tapered, being at an even 0.446" for 3/4" below the shoulder, then going back down to 0.444" and then back up to about 0.450". Inside neck diameter is now 0.277" (should be about 0.266" after firing), so even the thick part of the barrel expanded over 10 thou! That explains the "difficult" extraction.


    (Click PIC to Enlarge)



    SUMMARY: I submit that my Eaton Carcano is not inherently dangerous so far as its design (action strength and receiver-barrel integrity) is concerned. I doubt that my example was "accidently" made exceedingly strong, so I say - "Myth Busted".

    Note: The opinions expressed herein or statements made in the article below are solely those of the author, and do not necessarily reflect the views of the Military Surplus Collectors Forums, or the ownership and moderation group of this site. MILSURPS.COM accepts no legal liability or responsibility for any claims made or opinions expressed herein. Also, please note that neither the author nor MILSURPS.COM recommends that any member of these forums, or a reader of this article, try this type of experimentation without the proper knowledge, equipment and training.
    This article was originally published in forum thread: "Myth Busted" - Proof Testing an Eaton Carcano Rifle started by Badger View original post