[CurlyDave]

Sorry Mikey. I think you've got the U.S. Army confused with Mikey Dukakis. I've never heard of or seen a "rifle" attached to the front of a tank. You're right. You don't know anything about firearms.

The terms "rifle" or "cannon" are used to describe arms with rifled barrels (helical groovers inside the barrel) vs. smoothbore barrels, which are cannon.

I have seen 20-inch naval rifles (20 inch diameter, rifled bore) which many would call "cannons" and be wrong.

It is not at all uncommon for rifles to have 4" or 5" bores, and be 10+ feet in length. Some tanks mount rifles, some mount cannon.

[ArrogantBustard]

Here's a nice 20mm Cannon:

It has a rifled barrel ...

I want one ... It would look good on my front porch.