Hi Rog - it's super easy, when you have done it once they can be stripped in a couple of minutes. For the last couple of turns when removing the front section a good tip is to hold a thick cloth in your left hand, push the front of the pistol into this and turn the whole gun pushing against your hand to remove the final few turns. Reverse this process to re-install against the spring pressure.
And don't forget to pull the trigger to allow the piston to be removed.
I have the Bulmer scans - please email me (see profile) and I will send them right away.
Max; looking for: Baikal IZH 61 side lever rifle