You're unlikely to get the barrel off without a properly-fitting pair of barrel blocks and a receiver wrench. They're eBayable, but I made my own from scrap steel.
With a three foot arm on the wrench the barrel popped right loose.
Pre-made bushings usually come bored straight. My Mosin barrel had a 7 degree taper at the breech, so I had to taper-bore the barrel blocks. It also required a couple of soft brass shims to get some extra "bite" to keep the barrel from twisting in the blocks.
So far, I've done a couple of Lee-Enfields, a Mosin, a P-14, and a P-17. The Mosin wasn't the tightest.
The original tightening torque doesn't have a lot to do with how hard the barrel is to remove. Decades of corrosion from water, leftover bluing salts, or corrosive primer residue is the major factor. Most barrel threads are covered in really nasty spooge when the barrel comes out.
Penetrating oil does help a bit, if you have the time to give each end of the breech a drop or two every day for a while.
Some Mosins have an extra screw under the front trigger guard screw, that goes between the trigger guard screw and the barrel threads. Make sure that's out before you try to remove the barrel. Not all Mosins have the screw, and not all are drilled all the way through, but on all three of mine I can see the barrel threads at the bottom of the hole, which made a great place to put penetrating oil when I took the barrel off one.
