Not sure,but all this seems a bit serious for Muzzleloader gun building! I'm not a scientist,but I've used epoxy to bed a breech if it was a bit proud off the barrel. Don't have any idea what shear strength,lap or peel compresion load smash rate is,but after 20 years of being behind the breach of my .50 cal southern gun,"Pox",the epoxy bedding is still tight and right,after a few thousand rounds through it,and Deer hunting 3 week's every year,shooting in all season's of the year,in all humidity and temperature variation's in Michigan. It's also in a very unstable bird's eye maple stock.
Also,did I miss something? Buying from a hobby shop rather than supporting one of our own? Not to be disrespectful,but,how so? Just curious