I successfully pumped my AR2078 with the Benji pump and did some tests in my garage 10 yd range, it's cold and rainy here today. I emptied the CO2 from the AR2078, and pumped it up to 1000psi. It takes 22 strokes to fill it from empty to 1000 psi (recommended safe limit), then I got 5 shots in the same hole at 10 yards (power is initially high and then falls about 25fps/shot), 5 more shots within 1/4" drop giving a 10 shot group in a 1/2" square. Then the next 2 shots are noticeably low by 1/4" each and it dies after that. There were only 16 pump strokes to fill it to 1000 psi after 12 shots taken. And the effort is about the same as a bicycle pump, so you can say 3 pumps = 2 shots, nearly the same as a SSP rifle like the Daisy 853.

Next step is to run it off a tethered regulated HPA paintball tank. How should I detune this to make sure it runs at non-PAL speeds? I have a icemaker TP seal in it and it runs hot. I experimented with different TP seals and I can get it down to 380 fps on CO2 ... but is it way inefficient to slow it down with restricting the TP? Is adjusting the hammer spring the way to go instead? Advice appreciated.

This is so much fun... I forgot for a while I still have to do work and taxes....Doh.