My first try would be a Wolff hammer spring.
Yeah, the 26# versions are GREAT! I'm sure you were thinking 20#, but, NO WAY I'll put a "light" mainspring on a big bore.
These guns rarely shoot "one ragged hole" groups out of the box. It sometimes takes a while to find the load your gun likes.
Definitely learn to shoot the gun off of a sandbag or two. Practice your trigger pull with soft recoiling .44 specials so you won't
develop a flinch from the anticipation of that .44 magnum Ka-Boom!
JMHO,
flatgate