I'd bet they did wait...those guys like a prank as much as anyone else does. I've been looking at a lot of WWII footage lately, just studying some history of human craziness. When someone fires one of the big pieces (not even that big) you see the dust jump into the air for quite a distance from it - you know it's brutal to be there. That's some shock wave!
The lies now are so blatant you don't even need much in the way of information to rebut them. If this guy was freaked by an AR - which is the very most gentle rifle I have that's bigger than .22LR...it's obvious he doesn't know diddly about cannons, and IIRC there haven't been bazookas around to know how they feel for a really long time - they're really obsolete. And even then, it's a rocket, unwieldy and almost no recoil - not even that loud til they hit. So, often enough internal inconsistencies require only a bit of critical thought to debunk. Too bad no one teaches that anymore, and even regards it as non-PC and all.
At any rate, I had made up a few tests of binding agents, just sticking together some standard flash to see the effects on how it burned. I tried red gum/ethanol, which is used in one method for corning black powder without a hydraulic press (and the dangers involved) as well as some nitrocellulose dissolved in acetone (Varget). The flash (7:5 KClo4:Al) wasn't hammer sensitive before. After, the red gum, despite being a pretty concentrated solution, just really didn't hold the stuff together well at all. And it was still not drop test sensitive. However the Varget solution, also concentrated, got the result rock hard and it became percussion sensitive - still really numb, though.
As to plain burning when bound, the red gum made a chunk hard to ignite with a torch(!). Burned slower than usual after that.
The Varget version was easy to ignite, and while somewhat slower than without (everything is!) - had more energy and the little chunk flew off like a rocket.
I chose varget as it is closer to pure nitrocellulose than most of the other stuff on my shelf. Bullseye might have been interesting, but it gets gooey when warm - all that nitroglycerin. Useful to have around if you have the odd chest pain, though.
That looks like the binder to use with the "real" stuff. I do want to find one that doesn't need chlorate (perchlorate is a lot safer...), and I'll perhaps try a mix with sulfur sensitizer and perchlorate to see if I can get it sensitive enough.
Phosphorus sesquisulfide would be cool, but I bet hard to get - it's what made strike anywhere matches work.
I also need to test with the abrasives - they added quite a lot of sensitivity to the chlorate mix. But this is not my main track, it's just something I do when there are a few minutes to spare.