If you are looking for a lightweight varmint rifle, any of the small rimmed .22 or .17 cartridges will be a fine choice. If you put a heavier barrel on it, consider installing a rimless extractor and chamber for one of the .22 or .20 caliber rimless cartridges with a .223 case head size. Chamber wall thickness at the barrel threads is the limiting strength factor, not the action itself. For larger game, any of the cartridges in the .30-30 case family work well. Bob Snapp, who specialized in building custom rifles on these actions, had one in 7x30 Waters that he used for years as a deer rifle.
