Getting older and less happy with recoil, I would like to convert a CZ 527 left hand .223 rifle to a 17 or 20 caliber (17 Hornet, 17 Fireball, 20 Vartarg, etc.). The gun would be used mostly to punch paper, but varmints could be in it's future. Some questions I would like to ask are: can one use same magazines with the smaller calibers, will ejection be a problem with conversions to small calibers, what barrel and twist should I consider, any other considerations one might need to make in making a conversion like this?