Definitely give stick a try. It sounds antiquated and imprecise, but I default to stick and TIG over MIG. Before I got my TIG, I used to weld motorcycle exhausts with 1/16" rods. Stick will teach you to weld, if your welds look solid, they will be solid (in most cases). MIG/FCAW can trick you somewh...

The failure pressure of PVC is irrelevant, the failure mode is the critical part. The physical forces on a handheld pressure vessel while pressurised can cause more than enough stress in stress risors to promote failure, which is generally fracturing versus tearing. No other commonly used material f...

Larger pilot valve, equal fittings from both pilots to the pilot valve, inspect both for any significant defects on the casement/diaphragm and she'll be right mate.

Dear god he's alive. Seemingly brought me back too...

This. Diesel compressors are a dime a dozen here, usually 250-300psi. Got to use one to blow out sand from a water bore. 8" 300psi water gun with a 100' barrel is awesome.

3 bar with oxygen, or air

Rag, that entirely depends on whether you want true recoil, or the appearance of recoil to the less educated viewer. You aren't gonna achieve true recoil without a heavy projectile, but for the rule of cool, I daresay a cylinder would be satisfactory. The alternate option is making your projectile h...

Short of personal experience, not really. Foil thickness varies from manufacturer to manufacturer. However, you're gonna be looking at a lot. Another option is aluminium barbecue trays, or soft drink/beer cans. Can you correctly define what you mean by a 3x mix? Will it be pressurised to 3 bar, or a...

I don't think you'd need to bother with a custom cylinder. You could consider tapping air from the barrel, or just using a second solenoid attached to the chamber. Fire both in unison. However, make sure you have a satisfactory buffer.

Excellent work Rag. Honestly don't have more to add than props

Question though, have you come across the Craft books by Max Gladstone? I reckon you'll enjoy them if you haven't yet.

I just used a series of 3/4" (20mm) PVC fittings, but to work in my device, I had to make them smaller. Unfortunately the fuel mix was a bit too powerful

Yeah, I tried PVC and an atmospheric pressure propane/O2 mix, but between turning the fittings narrower and you know, PVC, I had splitting problems and it wouldn't move my bolt simulator far enough. Stress testing on the fill valve/spark gap tomorrow (I hope). Built it in a threaded fitting so I can...

ITWOST, V1 didn't have the giddyup I needed, time to go over to a conventional(ish) hybrid cartridge. Hopefully my welding skills are sufficient. I expect 12ml at 28x should give me the required gas volume. If not, I'll be tapping gas from before the projectile for extraction.

Stealing my contest idea boy! Better not be touching oxygen....

Quite curious about your results with it though

Better call DYI!