Sanchez machine -->http://www.paintballgateway.com/smloaders.html
There a couple diff types of feed tubes like that, where you have a stick feed with a 90* adapter that fits into a normal vert feedtube (such as found on your blackmagic up there)
if I were you, I'd go to the hardware store and make me a homemade stock class feed with pvc.
what kind of threads (if any) are there on your feedtube? you could always have them trimmed down and add a clamping stye stock class feed (like pps makes). or tapped for ccm threads.
not to many stock class options for wgp threads (any?)