This is a debate I've stumbled across here a few times. From what I can gather, smoothbore seems to have won the argument insofar as Challengers (the only big name tanks which were still using rifled barrels?) are now being fitted with smoothbores, but a fair few people continue to defend the rifled barrel, citing HESH capability and a particularly long range kill achieved with a rifled barrel once during the Gulf War. I must confess my personal knowledge of the subject is very cursory, coming largely from forum searches and checking out "ra ra" videos such as the following: (Skip to 1:50) Could someone more in the know explain the debate? If rifled barrels really do have better range and accuracy, why the primacy of the smoothbore? Is losing HESH (high explosive squash head?) really that big of a deal, and was it primarily an anti-armour round (as described above) or a round for use against fixed positions (as I've read elsewhere)? Is it true that it's much hader to use autoloaders with a rifled system? Is it all just a question of cost and going with what's more mainstream and has the spares and upgrades which are easier to get hold of? Cheers.