300 PSI Pistol (FPS and damage pic)
Posted: Fri Dec 27, 2013 9:42 pm
Hey this is my first post here but I've been looking around for a few months and figured I'd make an account when I had something to upload, sooooo......
Here's my first upload, not the first "spudgun" I've made, but I chose to upload this one because no one wants to see my completely n00b cannons, right? Ball valves...heh...
The pistol:
http://i1375.photobucket.com/albums/ag4 ... fbf454.jpg
This is my 300 psi pistol, with a blowgun as a trigger. It's not exactly the most hi-tech trigger, but the objective was to be simple, yet effective. It's full metal construction, using sch 40 galvanized pipe and fittings. Epoxy is used for attaching barrels to a piece of 1/8" pipe, so they can be interchanged by screwing them on and off of the front of the blowgun. I take it to 300 psi with my shock pump and it works quite well.
C:B ratio varies with barrels, but i like to stay within 2:1 to 4:1. The only barrel I've made so far is a piece of 12" 7/32 (about 0.20 in ID) brass tubing. That barrel would theoretically only give a C:B of 0.78:1, but it's much higher due to the fact that galvanized pipes are larger than the size they are listed as, making the tank volume larger than the calculated 0.29 cubic inches.
Damage pic (part of a screw through 5 cans): http://i1375.photobucket.com/albums/ag4 ... 6a6307.jpg
I did some chrony tests on two kinds of ammo:
4 grain .177 lead free pellet (widened skirt for 20 cal barrel) - 549 ft/sec @ 300 psi
~7 grain 5mm ball bearing - 480 ft/sec @ 300 psi
Here's my first upload, not the first "spudgun" I've made, but I chose to upload this one because no one wants to see my completely n00b cannons, right? Ball valves...heh...
The pistol:
http://i1375.photobucket.com/albums/ag4 ... fbf454.jpg
This is my 300 psi pistol, with a blowgun as a trigger. It's not exactly the most hi-tech trigger, but the objective was to be simple, yet effective. It's full metal construction, using sch 40 galvanized pipe and fittings. Epoxy is used for attaching barrels to a piece of 1/8" pipe, so they can be interchanged by screwing them on and off of the front of the blowgun. I take it to 300 psi with my shock pump and it works quite well.
C:B ratio varies with barrels, but i like to stay within 2:1 to 4:1. The only barrel I've made so far is a piece of 12" 7/32 (about 0.20 in ID) brass tubing. That barrel would theoretically only give a C:B of 0.78:1, but it's much higher due to the fact that galvanized pipes are larger than the size they are listed as, making the tank volume larger than the calculated 0.29 cubic inches.
Damage pic (part of a screw through 5 cans): http://i1375.photobucket.com/albums/ag4 ... 6a6307.jpg
I did some chrony tests on two kinds of ammo:
4 grain .177 lead free pellet (widened skirt for 20 cal barrel) - 549 ft/sec @ 300 psi
~7 grain 5mm ball bearing - 480 ft/sec @ 300 psi