well heck, the biggest thing I ever fired was a Marine Corps M198 155mm towed Howitzer. That was... geeze over 10 years ago now. Those weren't no new fangled electroloading elevating autofiring gizmos. Those babies were 100% all manual. From unhitching from the 5-ton, to diggin the spades in, to elevating the gun, loading the round, and charge, to re-hitching to the truck, 100% manual... that ain't no light gun to be hitching and un-hitching from a 5-ton either. 6 men to lift that beast up to the hitch.
Have faith WhatsThatNoise, the era isn't over yet. The US Marines still use Artillery with soul (even more soul than tracked arty, if you ask me)... /ubbthreads/images/graemlins/patriot.gif