Since I asked my questions a couple of days ago I've manged to get the RR all squared away, shorten, curve and inlet the barrel tang, get the barrel fully seated in the channel and inlet the barrel underlugs in the process, draw file the barrel to get rid of the marks it had as delivered and sand it a bit to smooth it out, round off the buttstock 95% of the way to fit the sheet brass plate, and build two wood clamp holders as seen in Okieboys chunk gun tutorial to hold the whole thing in place while I work on it.
I even experimented with odd bits of saw and utility blades as scrapers in prep for those stages.
Being a pack rat end never throwing away most cut off bits of wood and metals sure pays off sometimes, especially in this hobby. I was able to use all kinds of leftovers to build the clamps, sand channels and scrape holes.
This is fun. Thanks for all the help so far. My forearms and hands are painful wrecks after these two intense days, but I have time to rest them before I get more shop time next week. Too many years tying shoes for a living has done that to me, not the work of building this club butt fowler.
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Thanks again to all of you who have chimed in with advice.