Basically, you seem to have an extreme case of "leaded barrel". I respectfully suggest that the post from riceone, which has been copied over from another forum, where I agree it was the best suggestion for the problem (bore plugged by broken-off cleaning rod) is not the solution here. The great length of lead plug, which having been poured in, will have filled any pits and scratches in the bore, not to mention the throat and part of the chamber, will make it effectively impossible to drive it out.
I think you will have to melt it out. That will require removing the barreled action, taking off everything you can (bolt catch, sights) and applying slowly increasing heat to the entire barrel. The best tool for this is not a blowtorch, but the wide-flamed torch that is used by roofers for sealing up bitumen panels on flat roofs and soldering copper or zinc guttering pipes.
Go to a roofer, place the barreled action on a couple of bricks standing on end, with the chamber end higher than the muzzle end. Heat up the entire assembly evenly, starting at the lower (muzzle) end until the lead flows out. And, as mentioned in the other thread, make witness marks for the foresight and backsight bases, in case something comes unsoldered!
Afterwards, you then have an atrociously leaded barrel to clean up. No real problem, just time. The barrel may be pitted beneath the lead - but if you don't try, you will never know - what have you got to lose?
- And good luck!