Modern Intermediate Calibers 009: The 6x35mm KAC/TSWG

The 6x35mm TSWG, also commonly called the 6x35mm KAC, is a round shrouded in mystery. Apparently designed by Knight’s Armament Company for the interagency counterterrorist program cryptically named the “Technical Support Working Group” alongside the PDW with which it is popularly associated, the round was apparently never adopted. However, it is interesting primarily as an example of a round with shorter overall length than the standard 2.2-2.3″ (56-58mm) OAL that has become ubiquitous for modern intermediate rounds. The 6x35mm TSWG was designed solely for the unique KAC PDW, but a more traditional AR-15 type rifle called the SR-635 was also chambered for it. Like the .300 Blackout, the 6x35mm was also designed explicitly for 10″ or shorter barrel lengths; KAC has advertised their PDW as being available with 8″ or 10″ barrels. To properly compare the round with both the .300 Blackout and 5.56mm, we will be looking at estimated velocity figures from both 9″ and 14.5″ barrels, although it should be noted that so far as I know, no weapons chambered for the 6x35mm cartridge actually exist with barrels of either of these lengths:

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