Don't know anything about wood or barrels but I seem to recall one guy using some
odd T-shaped lamination recently. Another thread (in which Foxfish was involved) discussed enclosed tracks & Delrin seemed to be the choice of those involved (searching for it now, it looks like there are several threads on this very subject) & I believe Foxfish might know where to source it(?).
Alternatively, you could try
"Unobtainium"
(just kidding, I believe that's what they call the secret low-friction graphite/polymer/ceramic used to make the nuts on the more expensive PRS guitars).
How should the spearline be rigged? I would prefer to see it attached at the back of the spear but I could see that being a problem with the enclosed barrel (but not impossible). And perhaps a s/steel pin at the muzzle as a line guide?
