I have several 500rd cases of both BH 50gr TSX and BH 77gr TMK. Trying to decide which one goes in my 8-inch AR (car gun) and 10.5" BRN-180 (truck gun). The range from an 8-inch barrel for the 50gr is limited due to the 2300fps min. expansion velocity. Doc Roberts photo's showing the 50gr performance from short and standard barrels is impressive. But the 77gr wound channel is even more impressive, and it allows more range with shorter barrels, but lacks the barrier performance. IMO, wound channels from most barrier rounds aren't that spectacular anyway after passing through car glass or car doors. Decisions, decisions...
What would be great would be if the 77 and 50gr had similar POI's out of the same gun at 50 yards. Then I could just stagger them in the mag. Out of my Geissele URG-I upper (14.5"), the 77gr TMK is actually within 1-inch POI of Federal XM193 at combat zero, which is very convenient since I can leave it sighted in for the 77 TMK and practice with XM193.