It's a cartridge of phenomenal design by Elgin Gates back in the '70's.
Dan Wesson 360 DW can also be utilized in this chamber along with all those mentioned in the preceding video.
It's one of my favorite handgun cartridges, championed recently by Mike Bellm for the TC break-actions.
Official Mike Bellm's TC Performance Headquarters, Thompson Center Arms Co, Encore and G2 Trigger Job instructions, TC Encore and G2 Trigger Jobs, TC Contender Trigger Jobs, TC Encore and G2 TriggerSprings, TC Encore and Contender G2 Oversize Hinge Pins, TC Contender and Encore G2 Hammer...
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I think the original posting is the best!