i don't know about the new ones, but the old ones didn't have a detachable mag- it had a mag that attaches to the floorplate, and then you swing the thing closed and latch it- so, right off, you NEED to design a different floorplate/magazine-there's also not too much call for 5 shot 338 mags- that belt takes up as much room as a couple of rounds
besides, i don't think it would fit in with browning's "hunting only" profile- i have yet to see anything "tactical" bearing the browning name or logo