The .22-250 is an extremely fine "dog gun".

I'd bite the bullet and buy an entire new gun. Savage is relatively inexpensive and they have a sound reputation for accuracy.

A varipower scope to 12X will work nicely and the Hornady V-Max 50 grain bullets are superb for dogs.

Ask the guys you're going with how many rounds of ammo you should take with you. At times I've taken over 2500 rounds of .223, .22-250, .220S, and .25-06.....It's a ball if you get the right town.