BLO is an ingredient in a great finish, not the entire "sauce".
Steve Bertram is a great gunsmith in CO that is very open to giving away trade secrets. Give him a call and he'll tell you the way to do a traditional finish and will give you instructions on where to search online for recipes, etc.
Slacum or an alternative like Spar Varnish is for wiping away finish between coats. The initial first or second coat may be BLO. Thereafter it may be a traditional purdey recipe that includes BLO, Venetian Turpentine, Mineral Spirits, and beeswax. For color, the traditional options include red alkanet root which can be sourced cheaply or the old trick of rusty nails in a small vial of vinegar for a couple weeks, then use the solution to provide color. Hairline cracks are filled with crazy-glue and then sanded while the glue is still wet to bond sawdust to it.
The key to success is being snail-pace slow and using way too little material. The more you procastinate between layers, the less likely of a screw up. There is a reason a London Best finish took six months: A coat a day for two weeks. A coat a week for two months. A coat a month for six months.