Whats some of you all’s favorite things to cut cosmaline? That thick crap on old surplus guns like nagants and stuff. Would deisel hurt the gun if I didnt get a whole lot in the barrel? Or should I just use straight up bore cleaner? Thanks
Get a heat gun and just watch it drip right off. Then clean as normal.
Take this for what its worth because I haven’t actually cleaned cosmoline off of anything but AK-47 magazines… I used 409 Citrus. 409, as in Formula 409 straight off the big box mart’s shelf. The citrus version did a good job of breaking the stuff down and make the mags smell nice. 
Mapp gas torch for metal and the power of the sun for wood. This is how I got it off my SKS, which was the last rifle I de-cosmolined. The first rifle I did was the M44 Mosin-Nagant rifle and I did not know the torch trick that my friend showed me. I utilized the power of the sun. As for chemicals I go over the rifle with Hoppes No. 9 and a t-shirt for a rag.
I forgot to add break the entire rifle down into parts when utilizing heat be it solar or torch.
Steamer.
hmm… i’ve always just scrubbed with whatever gun solvent i’m using. but then again, i’ve never de-preserved an entire gun.
I used to do it by dipping and washing and a bit of scrubbing in a cut in half 55 gallon drum that was filled with solvent. Seemed to do a good job with minimal fuss.