Just to close the loop, I took my 9 homemade caps out on a morning of shooting to see if they would work. I left out the binder in the mix and just used heavily diluted duco cement in acetone. I was shooting a franken-New Englander. This was an older TC 54 New Englander with a rynite stock that I bought for peanuts because it had a roached barrel. I sent it off to Bobby Hoyt who bored it out and recut the rifling to 58 cal with a 1 in 60 twist for shooting round ball. This makes for a relatively lightweight hunting gun that is a real thumper inside 100 yards and I will likely use it for elk next month. The rub is that it is a little balky on ignition and won't set off subs at all. With real black it reliably ignites, but I have to be diligent about keeping the nipple and channel clean in a longer target shooting session.
I used commercial Rem #11 caps to start, but soon after switched to me test batch. A success! All the caps went off and I had one failure to fire when I did not swab out the channel when I should have. I think the homemade caps were actually a little hotter than the commercial one.
I am pleased with how this worked out. I doubt they would fit in a snail capper, but for target shooting it really does not matter. I have plenty of commercial caps, but this is an amusing enough endeavor that I will likely keep making up homemade caps when I need something small to keep my hands busy.