Correct. The gastraphetes, or belly shooter. The verticle rest makes no sense. No recoil with one of these kinds of machines, after all. Someone misinterpreted that, and hence we have that bogus shoulder rest.
Only the Xantan machine, no one knows what the stock looked like, but I am going that route, spanning by leaning into the machine and pushing the slider, dovetailed into the stock, up until I lock it with a small bronze trigger. With sinew ropes, it should have very decent performance, with bolts a bit over 12 inches (based, like the rest of the machine, on the diameter of the springs. That is the formula the Greeks and then Romans developed over many years). I'm looking forward to doing some penetration testing with authentic riveted maile with subarmalis, shields, etc. when it is done next year.
One day, it would be fun to make a real Greek machine with composite bow instead of the steel one Schramm built. Siege engines are addictive, just like bows.
Take a look at the photos of our legio's ballista - just the spring engines alone weigh over 300 lbs. It is all ash, Fred, the builder, did a fantastic job with this. Assembling it was a bit harrowing, as you can see in the second shot. And the third shot is of Davenport the pug, in her tunic and gladius I made for her.
[attachment deleted by admin]