I did something similar on my Uber-Carbine.... Check out the blue lines on this chart.... 600 fps at 10 pumps, or two shots at 19 pumps....With a Disco hammer spring (red lines) I could get the same thing at higher velocity, but with a LOT more (and harder) pumps required.... Bob
Perfect concept, especially if you are trying to stay under 500 fps in Canada.... Beware of the velocity exceeding 500 before you get to the crossing point of the curves though (eg. 7-8 pumps).... I also built a 1377 designed to stay under 500 fps regardless of the number of pumps, and it's not easy to push really close to 500 where the curves cross because of that.... Here is the chart for that gun....It didn't matter how much you pumped that gun, no shot would ever exceed 500 fps.... .... Note that by the time you got 2 equal shots (at about 470 fps), however, there was a 3rd shot of 200 fps.... Bob
Nice work! With the longer barrel, you will retain a bit more air at the same setting. The longer barrel creates more "backpressure" on the valve like a longer exhaust pipe would on an engine...
Perfect concept, especially if you are trying to stay under 500 fps in Canada.... Beware of the velocity exceeding 500 before you get to the crossing point of the curves though (eg. 7-8 pumps).... I also built a 1377 designed to stay under 500 fps regardless of the number of pumps, and it's not easy to push really close to 500 where the curves cross because of that.... Here is the chart for that gun....Bob
OK gents, please help me understand this. I'm new to the air shooting hobby (blowing hot air not included) but are you guys saying that a 1322 (in my case) can be pumped more than 10 times and then shot twice without the need to pump?Thank you,Ted