Originally Posted by
andrewM
I am now furnishing Protek's diagnosis and solution to the problem; I am a little behind because my email server was down most of yesterday and today.
Many thanks to all those who responded with ideas and suggestions, all of which were passed to Protek. Thank you, also, to ggggr who phoned Protek twice to discuss the matter in person. I owe you a pint or two should we meet.
"Hello Andrew, in the end I replaced the piston that was originally fitted to the rifle. The one you received was either worn at the cocking notch or made with the notch higher up. Comparing it with a post 1929 piston from a working rifle it could be seen that the notch came down further. Neither notch was full diameter of the rod but difference was just about visible and certainly measurable. Still did not work with first piston so I replaced the sear with one from a mark 3 which held side by side showed a higher sear point and fitted. I fitted a tiny spring guide in the trigger/sear spring to prevent it kinking as the hole in the Mark 3 sear is slightly bigger than the one in the bsa trigger. I have seen the little guides in some older post 1918 BSA rifles. There was not one in your rifle as you brought it in. This lack of a spring guide would not have been the cause of it failing. I did of course try various sear springs during working on the rifle.
It now cocks consistently and cleanly. I am NOT prepared to fit a stronger spring as it would over stress the rifle and almost certainly cause deformation of the cocking link which was the first cause of it not cocking, there is now just enough clearance between the link and the piston skirt to prevent the skirt hitting the link on firing with the spring now fitted. A stronger spring may cause the piston head to compress more on firing meaning there is contact with the link on firing and resulting in the link bending or damage to piston at the contact point. This is not a theory I have seen before but with the tolerances in your rather worn rifle I think it is one that is correct. I would be interested to know what others think. Regards, Vic. "
Not all of this is clear to me, as I have never dismantled a springer but I think it will be clear to the technical experts here and I will certainly be interested in further views, as will Vic who, incidentally, will be at Kempton with a table and is worth meeting.
I hope j_potter manages to solve his problem, which seems to come from the same examiner!