The high grade stuff goes to art supply houses and, I suspect, the manufacturers of better quality varnishes. Reserve the dusty cans of BLO at the hardware store for mixing into your house paint.
I've always regarded Truoil to be nothing more nor less than a very thin wiping varnish- lots more oil and fewer solids than regular varnish. I kind of chuckle when I hear guys talk about laboriously applying a bazillion coats of Truoil to get a built-up surface barrier. Simply using spar varnish would've achieved the same result faster with the added benefit of more durability, UV protection, and enhanced waterproofing (although no finish is truly waterproof). Said finish can be manipulated (ie: rubbed out) at the end to mimic the look of the vaunted Truoil "oil finish" while producing infinitely better protection of the wood.
Truoil is the darling of the gun world not because of its superior properties but rather because of the marketing genius of Birchwood-Casey. Every gun shop in the land has a pegboard display of B-C products to include little bottles of Truoil. The idea of "hey, there's so much of it everywhere that it must be ok" also applies to we gun loonies. Not that it's bad stuff, just that there's better things out there.
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