I had one of those for a while. Grooves measured .433", and it had a really slow twist rate. It shot the Ranch Dog 265gr. bullets quite well, sized at .434", but only at full throttle. Never could get it to shoot normal sized 44 bullets, and it wouldn't work well with lighter loads. I sold it and bought a 357 version, and it's a whole different animal. Correctly sized bore, super accurate with just about anything, and way less recoil. I put a Smith ladder sight on it and it works great for the cowboy levergun silhouette matches out to 200M.