re: BLO

The secret with BLO is to only apply enough to cover the wood on the first coat and then wipe off  the rest after about 10 minutes and buff it.  Subsequent coats go on super thin and need to be buffed after an hour or so to remove any excess.  Buff it rigorously enough that the friction generates a little heat and the BLO will cure more quickly.  It still it takes at least 3 or 4 coats (or more) to get a good protective finish and it is my go-to finish for tool handles.  It provides a silky smooth finish that feels great in the hand so should be good for a pen too.   I actually use Tried and True Varnish oil which is BLO with a little bit of varnish but the application technique is the same.  

Of course for a gun stock pen, I would be tempted to use Casey True Oil.