I've no experience with TSS shot, but from research conducted by my turkey hunting Friend, Buck Hamlin, pattern density is a more reliable killer of tom turkeys than shot size. Buck is a turkey fanatic and when I visited his shop some years ago he showed me his personal "research". On one wall of his shop were the neck vertebrae and skulls of all the gobblers he'd bagged to that point (he's added many more since); he'd cleaned all flesh from those bones and wired them together. As we visited he'd take down examples, pointing out and counting the shot holes in the bones; a couple of which showed two strikes, and his conclusion was that all that was required to kill a turkey was one pellet strike in the skull or neck vertebrae. So, and based on his personal research, he believed in pattern density and small shot; his favorite load at the time being hand a loaded 3" 12 gauge shell with 2 ounces of #8 shot. Buck is a tinkerer and for that season he was using an A-5 with a 3" chamber, and he'd modified the original barrel by installing one of his super tight choke tubes; he'd also installed a V-notch rear sight, which looked a bit odd as it was offset to the left side of the rib, but gave him the ability to consistently place the shot charge shot to shot. To prove the effectiveness of his modified Browning barrel, showed me a 40 yard pattern he'd fired with #8 shot; and 90% of the pattern could be covered with a ball cap! I don't think he uses the same gun year to year, but his weapon of choice is always something he's made or modified from muzzle loaders to vintage breech loaders; and they've all have been modified with super tight chokes designed to pattern effectively with #8 shot.