SpudFiles

SaladTosser:
Yeah, you get "net recoil" (the gun has velocity after firing) from a dryfire because you launch the air, and air has mass. I guess that you typicaly don't call air "ammo", but anyway...

Yep, If by 'estimated projectile speed' you mean what, say, the GGDT (which assumes a unmoving gun) would tell you.

Aaron:
Your problem is that you are having trouble wrapping your mind around movment being relitive;
Measured by the ground:
The car is going 100 feet/sec.
The gun changes velocity by 3 feet/sec when it fires - when the spud leaves the gun, the gun is going 103 feet/sec.
The spud is launched at 3 feet/sec, because it changed velocity -100 feet/sec when you launched it. 103+(-100) is 3.

Now, if you fired the gun at a crono on the car, it would read -97. -100+3=-97.
If it was attatched to the gun, it would read -100.
If it was attaced to the ground, it would read 3. -97+100=3.

(note that cronos can't give negitive readouts, so the negitive signs are basicaly indicating direction)

oh ok i get it

now seems a great time to bring up my other question
i had to sand my 2" pipe so it would slide right thru the tee but it has to go into a 2" female adapter after that and its not a realy tight fit in the female adapter which is where most of the force from the piston will be pushing so could it fly back, off the pipe and hit me

P.S. by not realy a tight fit i mean i can push the 2" pipe all the way in to the female adapter with not much effort

i hope it dosent come off

you might want to get a new female adapter, it should be snug about 1/2 way into the fitting, something that slides in that easy might be a bit dangerous

Damn it!!!! ive already glued it

im having more trouble getting the piston to seal than anything maybe ill scrap the gun if it dosent work