You can take a fresh bullet and stick it in the end of the barrell. This is worn out!
If that's the case, no amount of careful handloading is going to help. It might be counterbored where the first inch or so of the muzzle is drilled out to get to fresh rifling.
If anything, I'd try a bullet with a lot of bearing surface like a 200 gr sierra or a 170 gr hornady RN.