Glad to know I'm not the only one out there. I am relatively new to air gunning, but have been pretty busy. I have only been in a few years. I have three Drozd Blackbirds. Two of them are fully modded with Sergey's Board's in them. One has a Jim C. 23' tactical barrel, AR stock, and external battery pack. The other one has Jim C's 15" SMG barrel with his wire folding stock, and external battery pack. The other Blackbird is completely stock. I also have a Bumblebee I am quite proud of. It has a Jim C. wire stock, and HPA adapter. It can fire 4000 RPM. It has a prototype board in it Sergey made for me. I had to make a magazine spring for it because the stock spring could not keep up with the extreme ROF. In doing so I lost the capacity of eight bb's so you get a full third of a second of trigger time with each mag. I have two 90cu paintball tanks, and a scuba tank. My regulated pressures are 1000 psi, and 1600 psi. I have shot bb's over 1000 fps using helium. At first I thought I was breaking the sound barrier because shooting helium at 1000 psi is loud enough to hurt your ears. It also shot through about 400 pages of a phone book. I shot it outside, and could hear the distinct crack you hear when something breaks the sound barrier, I bought a Chrony to find out. I was actually shooting around 1000 fps. I concluded the crack was caused by the helium breaking the sound barrier as it followed the bb out of the barrel.
I like to tinker so those guns are a good fit for me. I have an unlimited supply of HPA so I do lots of shooting, and testing. I have a range where I work so when things are slow at my real job I like to punch paper, and tweak my guns. I seem to remember shooting a gun at a fair just like your description of the Feltman. That was loads of fun. I also have a Lark my uncle gave me. I rigged it up to accept shop air, but I never could get it to work. I went completely through it, and couldn't find anything obviously wrong with it. I think the tube that feeds the bb's to the barrel shrunk over time.
Thanks for taking the time to reply, and letting me brag a little bit.:^)
Best regards,
e