in response to 1771 I have uploaded this cad picture. (this is like 5% of the assembly) but it looks very similar to 1771s. its use is classified for now.
Might I venture a guess as to how this works 
It looks like a very interesting design! I love it. I don’t think I’ve ever seen that style of loading before…
Unless I’m completely wrong
you may venture a guess, but I am betting its not what you think;)
Archimedes screw hopper that delivers balls through that hole?
I was going to say there are two options.
I agree with Hachiban in that the balls will be delivered from the hole. In proportion, it looks like you have a two inch roller or maybe a little more depending on desired compression.
As for mounting, I would say you’re more likely to mount it on the bottom since that angel creates too much of an arc (imo) but you could also be mounting on the top.
As for a gathering system, that I don’t know 
I see a thrower! (maybe!) Probly rotating and the balls are delivered through that hole. I’d venture to guess its mounted vertically. I think the ball storage is probly linear, maybe a spiral.
Whatever it is, it looks REALLY impressive, and I hope everything comes together as nice as this piece looks! good luck!
Loader side side plate for a catapult system?
LaFluer is the closest but the actual shooter motion has not been touched on yet. you guys are right that it is a side loader that is low in the chassis.
ITS A MODERNIZED PROTRACTOR lol