I've just restored a mk 1....and as suggested above.....and pulling and twisting worked.
Again my barrel was bent upwards, with the classic associated cracked stock.
I straightened the the barrel using blocks of wood and heavy duty g-clamp as described by the BB Peleter on the Airguns of Arizona Web site. It worked brilliantly and was very controllable.
Good luck...I managed to turn a Freeby scrapper into a useful rifle.
Cheers Steve