There is no evidence that there is a whit of difference between BLO and tung oil. None. They have the same waterproofing qualities, which is nil. Any difference between the two in appearance of the final finish is in the mind of the beholder. Varnish makers today routinely switch from one to the other when mixing their formulas, depending on price and availability.
The Arsenals used hot oil baths to submerge stocks in, true. But they interchanged linseed oil and tung oil at will, whichever was available/cheapest at any given time. (Although linseed oil was the specific oil called for in their manufacturing protocols.) Ditto the major gun companies, although few of them bothered to heat the oil baths- it was all about meeting a certain price point for economic survival.
Why did the Arsenals use oil finishes on gun stocks? Because it was the cheapest finish possible, not because it was the best possible finish. What did the Army care if a stock got ruined? They would simply discard it and throw another one on the gun.
It's amazing the amount of folklore and number of old wive's tales that has sprung up about the two oils over the decades. Most of the mis-information being a result of gunsmiths and backyard Bubbas not having access to reliable data and/or were flying by the seat of their pants- and further propagated by legions of devoted offspring and admiring followers who took their Pappy's word as gospel without investigating for themselves. But such is how folklore and old wive's tales in general come about.
