SpudFiles

BIg= very hard to pump,
small= easy to pump.

well if you weight like 300lbs all you would have to do is sit on it and let gravity do the work and then it could be like 4"pipe easily,so all you need to do is gain a few pounds and off you go!the the lil chubsters like me just put it to use.

Hose_spud your to agressive for these forums.... you make me sad

It could be 3" pipe with like 5" length... or it could be 1" with 45" in length... they both have the same volume so there going to be difficulty to pump....

Like Demon said... size matters and If your Piston seals and you make it with the check valves the right way it will work fine.... just make sure that you drill holes in the Non-check valve sides end cap too, so it will allow air above the piston....

hey I made one and i thought it could help you making your own. It is very simple, i use a 16grams co2 bike pump with manual regulator, a blow gun rated to 12 bars, and the barrel is made from a 14/16 aluminim arrow and is attached to the blowgun via a homemade adaptor, using a pen and bondo paste.
I attached the 1/4" union, with superglue and bondo, it doesn't leak and resists to pressure. that way, i just have to connect the blowgun to the pump and open a few seconds a very small flow from the cartrige and when i get the desired pressure, i just turn it off, and shoot., shoots pretty quick (350-450 fps depending on pressure) it's a .177 and i shoot pellets. perfect fit for the pellets. (sometimes, i need to blow some air to make it go down.

what is that, like $.70 a shot?

Beebs I think that since he has a manual regular mounted, not a lot of CO2 is used for every shot.

What I have to ask is if its semi-auto, do BBs fall in from the top part and you fire full or semi-auto, or do you have to load a shot each time?

You can make your own check valves for not that much if you're worried about the price for your own pump.

Here is it, i don't know what's the cost per shot, but it uses a small part of the capacity of the cartridge.
It isn't semi auto, i have to load each lead after the previous shot. Sometimes they fall right the the end of the barrel, but when they're to wide, i need to blow some air to make them go down.

You can calculate how hard it will be to pump.

pi x radius^2 x the psi you want to achieve = the force it will take.

A 1" pump would be 3.14 x .5 = 1.57^2 x 100psi = 157Lbs.

That means it would take 157 pounds of force to make 100psi with a 1" pump.

12v compressor rigged to a car batter sounds the easiest to me.

i'm gonna do that when the fellas and myself go TP'n.

If anyone wants a 12v car compressor here is one for only $8.95

http://www.surpluscenter.com/item.asp?U ... atname=air

i think that a regular old pump for like basketballs and stuff would work fine but after like 100psi its probabely insanely hard to pump