On materials of FPs: I'm fine with restricting materials, but does this mean that all FPs will always work? I'm just thinking that it took centuries for us to figure out how thick a cannon should be to prevent explosions. Also, some people have deliberately used what appear to be failures to gain certain advantages. The chinese stuffed bamboo shoots with gunpowder and shrapnel, setting them off as large, one-use hand-cannon/shotguns. The romans designed their spears (Pila, right?) to crumple after being thrown, so they could not be thrown back and any sheild hit would be impossible to fix and thus rendered useless.

Single use things are way easier to (mass) produce, and are quite practical in military. If you have masses of conscripts but can't afford standard weapons for them, or just a heavy weapon for ambushes, this is the way to go.
Most militaries do it even today, in the form of recoilless rifles, wich are really just tubes with rockets stuffed inside.

As for implementation, in the TE certain tags (such as handheld) might allow for a special "one use" option, wich would really be just a checkbox. It would make the TO cheaper, simulating simplier designs.

But we still don't know how to handle "May or may not" work. Again, medieval cannons weren't popular for so long because there was always a chance they would explode, but people still used them as it wasn't a certainty.

There's a whole thread for leveling? Belgium my memory, reviving now.

Edit: Either the thread does not exist, or the search function really fails. Creating new topic.

I tried too. I think maybe this was a thread that was either a) part of the early tech tree discussion or b) on a previous forum.
I shudder to think how hard anyone would have to search to find one of my threads...

Anyone who can access it, post the link.