Hand made belt fed .22.
https://www.youtube.com/watch?v=sAfPc6RPe-w&feature=youtu.be
google for "Lakeside" machine guns.
they made Browning 1919 in 22LR, 22Mag and also M2s in the same caliber. Most of the M2 were in 22Mag.
they also made a 1917 water cooled version
then you can also look at the "razorback" it stared off as a standalone belt fed 22 and then they made an AR upper .
you can find them from time to time if you really want one.
I got the 1919 and a complete version came in a wood chest with manual and 2 mini 22LR ammo cans.
the gun itself is permanently mounted to the tripod base.
if you want to see the cats meow,
https://www.montysminiguns.com/brian.htmhe made one in 22LR but there isnt much on the web unless he reposts what he had before. But it was a really cool toy. spent alot of time & money to get it working.