For a 1'' PVC air cannon, this thing is tiny. the gun is about 1 foot long. The barrel is not necessary, as the ball valve breech acts as a short barrel, but i choose to use a barrel for improved range.
Yeah, this looks more like a compact rifle, this one of mine is probobly more compact:

And it is a 2 hand rifle and has more chamber space and a longer barrel. Now, granted, it's a .50 cal, but still.
BTW, my rifle is over 6 feet long. and will toss a bouncy ball a half mile easily.
I kinda find that a bit hard to believe, you do realize 1/2 mile is 2640 feet, I highly doubt a pvc rifle could go that far. I'm not saying for sure, but I'm just saying that's hightly doubtfull. My large pneumatic .50 cal goes only 500' at 100 psi shooting wooden dowels.