Thanks for the boot towards modern drafting, Double D. However, I will have to join a Yoga group to get my exercise if I just sit in a chair and stare at a monitor for more hours. The way I get these quick sketches or in-process partial drawings requires some real contortions. Just to draw these quick sketches for this thread I had to thread my feet into ankle-breaker territory, ( Mike had a row of 100 pound Brooke tubes in wooden cradles) exactly where I had to stand, then to get the photo I had to lean way back over our little shaper and yet put one arm up over the engine hoist also in the way and, and at the same time, stretch way, way up with the camera and flash unit to get the "bright spot" off of the drawing, itself. Thanks DD for spurring me on. I will look into a training program. Are you sure that they will attempt to train a fellow who is really famous with his grandson for knowing all those dinosaur names, because he used to see them grazing in the fields while walking to grade school?
Cannon Cocker, I get it now and I have seen that form of rifling before. That description is very clear and I understand what you have now. Thanks again and your comment about, " there is no need to have a throat or rifling ramping up to the lands because it is not a breech loader" shows Mike and I that you totally understand what we were trying to get at with the "below the surface of the bore dia. rifling grooves". Thanks again. Your rifling can be called ratchet or hook-slant, but we now understand it's form and you're description indicates that it is quite different that either the Blakely or Brooke pattern. Thank you for taking extra time to describe your cannon's bore so clearly.
VA Rifleman, Can you see it now? Can you see it now? How about now?
Thanks for the numbers and another very clear description. I am speculating, but there is obviously expected to be some movement of the projo, at least two inches, before peak pressure is achieved which flairs out the sabot into the grooves. It has been our experience that a slight increase in powder charge from what is expected, is
sometimes necessary to get this engagement of the rifling done. We followed standard safety protocol by starting low and gradually going up to a charge which indicated engagement had occurred, because of the dramatic effect on accuracy. The results of those extensive experiments are displayed in one of the photo galleries on our website. Thanks again for sharing the details of your cannon's bore with us.
Mike and Tracy