Rebarrelling Mosin
Depending on type and date of manufacture, Mosin barrels can be hard or ***^&*! un-movable.
First thing is to strip as much off the barrelled receiver (including sight parts.
Then get or make a proper barrel vice and a proper receiver wrench.
Barrel vice is usually two half bushes of brass or aluminium, fitting in-side a clamp ( 1x1 bars) which is bolted on both sides ( 5/8" bolts minimum) and the lot welded to some heavy angle and locked into a heavy bench vice ( mine is a 8 inch Record, cast steel). The Barrel vice is located as close as possible to the Barrel shank ( on a parallel section of barell ( there is a slight taper, which can be "scraped in" to the brass blocks).
Then take the receiver wrench (NOT a toothed Pipe wrench or similar "Bubba tool") which has been fitted to the profile of the receiver...I have a cut from solid wrench for "Hex" (Old Mosin) receivers, the inner surface lined with copper sheet), and a "Vee Block" clamp -on one to use with Round receivers ( M91/30 type). Both these Rec. wrenches have a 1 inch handle, solidly welded onto the main frame, over which I slip a HD Black steel Pipe ( 1 inch Nom. Bore., and about 5-foot long ( 1,5 metres).
Every thing is oriented so that the "Cheat bar" is horizontal, and then I can do one of two methods....I whack the end of the bar with a 14 pound Sledge to "Crack" the joint between barrel shoulders and Receiver shoulders; some times, I try to swing on the bar with my own weight, first ( 220 Pounds) to see if it will "crack.".
IN any case, prepping. the joint by an overnight soak with a penetrating oil is useful.
Sometimes a five minute heat with a Bernz-o-matic hand held torch will help "loosen" the Joint.
It is essential both Vices (Barrel and Receiver) are tighened to max without shearing the bolts. Powdered Rosin may be needed to prevent the Bushes from slipping on the Barrel ( Older Mosins are very smooth (well machined) WW II Mosins are pretty rought surfaced, so will grip better.)
If the first try doesn't work, try the Torch method, and then cool the barrel with some cold water compresses. Leave the receiver hot ( "holes expand when heated") and try the Cheat bar again.
Eventually you will get the barrel out... if NOT,as a last resort, if the Barrel is a Klunker ( or Sewer Pipe) one can simply cut off the barrel just in front of the receiver, bore out the stub to just Thread depth, and then pick out the remaining Barrel threads from the Receiver Threaded hole.
Good barrels which are well seated can be "relieved" by cutting a fine slot just in front of the receiver ring, all the way around, to relieve the compression of the metals...Barrels were regularly "Machine Torqued" when assembled. A simple Hacksaw can do this slot. Depth to Thread core diameter.
Now that you have the barrel out, what are you going to do...put a replacement (Good) Mosin barrel back in, or put in a NEW Barrel, maybe in another calibre???
If putting in another barrel, threads will have to be cut. I forget how many TPI and diameter the Mosin barrel is ( De Haas has the details, as does the NRA Book on Gunsmithing) but REMEMBER: The Mosin Threads are all British Whitworth Form ( 55 degrees) NOT US type ( 60 degrees).
Best regards, Doc AV
AV Ballistics Film Ordnance Services
Brisbane Australia