Hey agd68~
Moose sinew would be super-kill! Since a moose is so big and has such long legs, I don't think there'd be any better in North America! It would have to be at least 3 times the size of my whitetail sinew
, of which my biggest piece is 3/8" thick, by 17" long, and sinew is always the bigger/longer the better. If you got some moose sinew you'll be the envy of a lot of primitive archers, including me!
Get it if you can and also realize the value! You would have a lot of leverage on a trade, or could probably sell it for a way better price than whitetail.
~~Papa Matt