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Ballard rifling on Marlin336A date?

Ischia
What was the last year of the deep cut "Ballard" rifling on the Marlin 336's When did the new style "Micro-groove" come into production on th Marlin rifles.

Thanks,

Ischia
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  • 11b6r
    Cut & Paste- refers to Mdl 39As, but the 336 should have been same time frame.

    In 1953 Marlin Firearms was issued US Patent #3,100,358 for what was named MicroGroove Rifling which was a departure from the standard "Ballard" or cut rifling. The purpose of Microgroove Rifling was to increase the speed of producing rifle barrels.

    Microgroove rifling is described in the patent as having 5 grooves for every 1/10th of an inch bore diameter, and that the driving side of each land would be "tangentially disposed" to prevent accumulating fouling in use.

    Marlin introduced Microgroove rifling in their .22 rimfire barrels in July 1953, with 16 grooves that were .014" wide, and nominally .0015" deep. Ballard Rifled barrels have grooves generally in the range of .069-.090" wide, and .0015-.003" deep. This change was marketed in the 1954 Marlin catalog, as having numerous advantages that this new form of rifling had, including better accuracy, ease of cleaning, elimination of gas leakage, higher velocities and lower chamber pressures. The catalog also claimed that Microgroove Rifling did not distort the bullet jacket as deeply as Ballard Rifling hence improving accuracy.

    Microgroove Rifles barrels have a reputation for accuracy problems with cast bullets due to the increased bore diameter generated by the shallow grooves. Use of oversized bullets has great effect on solving this problem, restoring accuracy to level seen from Ballard Rifled barrels. These grooves are inside the barrel and create more bullet spin. there is usually 16 groves in a standard 22 barrel.
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  • RounderRick
    Hello Ischia - Early 1956 was the first advertising annoucement for all high power cartridge rifle production. As 11b6r posted, the use in rimfire rifles came first, then Model 322's (bolt action .222), and finally everything else. Keep in mind that, like other large facilities, old inventory might get laid aside and filtered back into the production stream some time later. There are a lot of ways a Ballard barrel might turn up on a somewhat newer rifle. GoodLuck - RounderRick
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