First spudgun using lots of paintball parts

[ToyBox]

I've been lurking and reading through various builds to help me prepare for this build.

The goal: A spud gun that will fit inside a guitar case that meets the standards set out for local paintball scenario games (fires a specific Nerf projectile at a maximum velocity of 150fps). The guitar case is my idea because I've watched Desperado too many times.

The parts I had to start with: Air tank (48 cubic inches at 3000 psi with a regulated 800psi output), ASA connected to a low pressure regulator that can be adjusted from 75 to 450psi and finally a handful of remote lines designed for use with 800psi output.

The parts I purchased after reading through the forum: Various schedule 80 ABS elbows and nipples, Schedule 40 threaded 1/2" to 2" adapter for the barrel, 2" ABS barrel, schedule 80 1/2" to 2" adapter feeding to 2" to 3" adapter. The only suspect part is the 3" pipe because it doesn't list the schedule on it so I'm not 100% confident of its pressure rating. This worries me because it's going to be subject to more pressure than any other part.

This hasn't stopped me from hooking everything together for testing.
I didn't check the adjustable regulator pressure before hooking it up and the first shot measured 250fps . Then I checked it and discovered that it was over 300psi going into my tank, which exceeds the ratings of the parts so I dropped the pressure down to 90psi to see what I got.
At 90psi, the Nerf left the barrel at 100 fps.
at 140psi, the Nerf left the barrel at 120fps.

Now that I know it works, I'm going to build a sprinkler valve and fit it all into the guitar case. More pictures to come.

[ToyBox]

I noted the stress lines on the expansion chamber. Closer investigation revealed that tube is not pressure rated at all so I will not be using it moving forward.

This is a shame because it's lots of fun to play with.

[Doodmens]

How much did your paintball tank cost? I've been looking for a cheap one with a regulator but can't seem to find one below $60. Doesn't need to be big.

[Gun Freak]

Then I checked it and discovered that it was over 300psi going into my tank

You're very lucky sir!

About what you said about the pipe having to hold the most pressure... each part is exposed to equal pressure. Always remember your gun is only as strong as its weakest part. You have done the right thing by choosing to stop using it.

Thankfully they are cheap parts and you can rebuild a properly rated PVC chamber for very little money. Some simple 2" sch 40 PVC and the appropriate NSF-PW fittings will serve you just fine. Happy spudding