Thread: Home Brew Black Powder........Craft Powder?

I once had the idea to build a 2 Pounder Whitworth Breech loading cannon with a 40mm Bofors barrel.
I found a number of barrels but their owners were reluctant to sell knowing they were going to be cut in half.

But I did play around enough to have a play at making double and triple helix threads in the workshop like the Whitworth Breech threads.
It's great to hand to an engineer and see their face when they realise why the thread looks a bit strange.
The multi helix threads are very cool, so that one turn of the breech block engaged enough thread surface area to contain lobbing a 4 pound projectile some distance

But not as big as an anvil