“Custer had three Gatling Guns at his disposal. But Custer thought they would slow him down, so he left them behind at the fort.
This guy at the link below says Custer was right in declining those guns. They were completely unsuited for the terrain. As for me, I’d have taken those guns,...” [Leaning Right, post 5]
“...The wheeled guns were not nearly as heavy to haul as the ammunition boxes.” [odawg, post 49]
A more careful look at the topography, along the Little Big Horn River in southeast Montana can help.
The ground that the 7th had to traverse that June day was not all gently rolling prairie. Patches of exposed clay, highly eroded and crisscrossed by deep gullies and steep hillocks, are easily seen from the battlefield. Wheeled vehicles could not have crossed it; lightly burdened men on foot would have had trouble. Laden horses and mules would have had a tough time. They’re called badlands.
I believe the calvary opposition during the battle was along the river and up a small hill. Maybe not suitable for positioning those guns.