The M102 was introduced in 1964 as a replacement for the WW2 M101 105mm Howitzer. It was used extensively in Vietnam as an airmobile gun, being carried by CH47 Chinook helicopters to the tops of mountain firebases and also on river patrol boats (The larger Monitors) It used welded aluminum carriage and trail so that it was able to be towed by a 3/4 ton truck, whereas the older gun needed a 2 1/2 ton truck to haul it. The firing position is also lower.
The M102 has also seen action by the US Armed Forces in the Gulf War and Afghanistan, but has recently been replaced by the M119, an airmobile gun designed by the Brits. The National Guard still use this gun, and was last used by them in Iraq in 2004. It is still used in AC130 gunships.
Being hauled by a CH47
Mounted on a river monitor in Vietnam
In a convoy in Kuwait
This M102 guards the old I.O.O.F. Cemetery in Amelia, Ohio
I came across some small cannons a while back built by Blackpowder-Cannons.com. They were small affairs, but sturdy, and could throw a cement filled soda can quite a ways. Then I ran across the proprietor's other projects and it all got interesting. The following picture is one of his soda can cannons... and only 300 bucks.
Then I ran across an old forum post of his showing off his replica miniature Hotchkiss revolving cannon, muzzleloader of course!
And here is a video of the Hotchkiss off his old youtube channel, cannonfab's channel
And he must get into restoring old cannons, here is one of his videos from his newest channel after restoring an old Maxim Nordenfelt gun from the Spanish American War. Looks like quite a handy guy.