T15 DS11, 12.5" Dual-feed, Smoothbore, BigShot AssaultBR-1-12.5-BA-AT-T15-684-MT
Bore Length: 11.5 inch Control Bore / 12.5 inch with Tip
Bore Options: .684, .687
Finish: Matte Finish
M16/M4 Muzzle tip included
The 684 slows down the FS round to better match the speed of the round ball. You chrono the FS then test the round ball, adjust to field regulation speed until you find the sweet spot for both. That way you can switch between the ball round and FS rounds on the fly.