There's not a thing wrong with putting an 18 or 20 twist barrel in T/C Hawken, Lyman, or any other spare stock with lock you have, adding a tang sight, and banging away at long range targets.
It's a gun, a stick with a barrel and mechanism to make it go boom. This might be a simple, quick, and relatively inexpensive route to get a silhouette gun running.
Go ahead and bed the barrel, then pillar bed and attach it with allen head screws if you want, or even glue the barrel in - do whatever is required to improve the breed.
More ideas-
- add a front sight extension to increase the sight radius,
- install a modern scope. External adjustable mounts are expensive, so install a 30mm scope to get enough come up to hit those far targets. Burris rings with elevation compensating inserts might work if you are stuck with a 1 inch scope.
- hotrod the lock; a coil spring with a higher spring rate along with a modified sear to reduce the hammer arc, ball bearings in the joints, and lighten the hammer.
- install a handstop and no pulse sling if not shooting off cross sticks. Heck, use the sling and sticks.
- modify the bottom of the forearm to sit more precisely in the notch of cross sticks.
- Have fun, and don't be afraid to try something different.