This was a Winchester development contract for a design study of a multiple flechette rifle system from Frankford Arsenal during 1968. Winchester had already done in-house ballistic studies during 1962 with a 10mm case version based on modified 30-06 cases and used these results to propose a 9,53mm multiple flechette cartridge that could fire four flechettes of 9,4gr each at a velocity of over 4,000 fps. To reduce cartridge weight, Winchester used an aluminium alloy case.
The brass cased versions were made at the East Alton Plant for internal ballistic tests. These two cases were loaded with the 0.12inch Bloem primer, that used a separate anvil which was inserted in the vent hole prior to seating the charged cup. Note also the difference in the width of the extractor groove on the WCC 69 version.
These aluminium cases were loaded with the Winchester No. 120 brass primer and the different lots were identified by letters added on the headstamp. Cases were loaded with different coloured sabots.
The WRA 70 case is also loaded with the Bloem primer.