Sights I fit up, polish, etc, Then remove for bbl finish.
I blue or brown the sights as needed as separate pieces and then re-install on the completed gun.
A dab of grease in the dovetail when re-installed makes everything go together easy.
They shouldn't take gorilla effort to assemble but enough to keep them in place.
That way any tweaking while sighting in won't damge anything.
No one likes to see marks around the sight bases that look like a rock was used to make adjustments.
Bbl tenons I leave in place and never (re)moved once installed.
No need to as far as I'm concerned. I want them to stay put so the cross pin lines up nicely.
I often soft solder the dovetailed tenons in place so they aren't going anywhere.
Lately I have been just soft soldering the tenons flat base right onto the flat of the bbl,,no dovetail cut at all.