I used the heat gun when I first got it. It did remove some cosmo. The handguard came like that. I do not mind it much but hey, I does not hurt to ask anyways. So BLO is a good idea once I completely remove all the cosmo?
Yeah man,
Keep at it with the heat gun.
Melt out all the cosmo you can.
Wipe it away and repeat many times.
You will never get it all out because it has literally been bathing in it for 50 years or so.
Once you get out enough (when you are satisfied) use Boiled Linseed Oil mixed with Varsol (paint thinner) in equal parts for the first couple handrub sessions. The thinner makes the oil seep deeper into the wood for the first couple applications. Then you can just go to straight BLO after that.
I refinished an SKS stock by using mineral spirits to strip the shellac. Then Easy Off cleaner to suck out the grease and grime of years of handling and abuse. The s**t sucked the stock clean! Looked like the wood was just cut to form the same day! very raw. I would not recommend the Easy Off method unless you don't mind lots of sanding to get the grain smooth again after the Easy Off.
But after sanding and finishing with the BLO method I described above, it turned out amazing!
If I'm not mistaken the stock on the M48's are Teak wood. It's a hard wood with nice straight tight grain. So it will sand right back down just perfect after the Easy Off
IF you chose to use that method.