In my limited experience using linseed oil, UNDAMAGED wood isn't really capable of of soaking up too much to where it leaches out in the heat. BUT,...I once had an M1 Garand that had a hairline crack in the stock; not so bad that it needed to be replaced, but was noticeable. At some point, either the arsenal depot or some previous owner had given the stock a newer coat of linseed oil. I fell upon hard times and held a garage sale back then, where (among other things) I had the Garand out on a table in the blazing sun for most of the day. As that stock baked in the summer sunlight, linseed oil continued all day to slowly ooze from the crack. Every 20 minutes or so, I'd have to take a Kleenex or paper towel and dab at the oil beading up. It never really stopped until I brought the gun out of the sun.
By contrast, back in 1989 when the Mosin-Nagants first arrived here after the Dole Amendment lifting the ban on surplus rifles getting imported, I got my hands on a Finnish captured and rebarrelled M91/30 that had been in deep cosmoline packing for decades. After using gasoline to get all the gelatinous goo dissolved, and then soaking the stock in the bathtub for 24 hours to help the dings and dents in the wood to raise and fill out, I let the stock dry out in our summer heat for 3 days, then used simple spray can polyurethane from Home Depot to seal it. The texture wasn't as glass smooth as brush-applied urethane can be, but was actually a bonus in my opinion, because it made gripping the rifle more secure and the slightly matte gloss wasn't as out-of-place looking as the higher gloss urethane would have been. I shot the living crap out of that Nagant over the next 20 years, and that simple spray on polyurethane finish was durable as all Hell and looked as good as it had when I first applied it.
