On a recent trip to Jamestown, I saw a couple of things of interest. First were breech loading swivel guns. I thought I knew about swivel guns but sure didn't realize that some of them were breech loaders. The breech block is a "mug" shaped piece. One gun might have several of these. They would be loaded in advance and in use placed in the gun, the wedge driven in, and then fired.
It's unclear whether they are fired by pouring powder in the touch hole which is then lit or by some other means. Since the touch hole has no chamfer to hold loose powder they were probably fired with a hot wire.
This cannon was interesting in the way the mount was constructed. The top plate of the bearing is notched to fit down over slotted tongues and then wedges that look like Jo's cotters - or at least half a cotter - are driven in to hold the bearing on. I always expected heavy spikes or lag screws to do the hold down, but after seeing these I see lots of advantages to doing it this way.
Alan
