BSA Standard Repair Query – which challenges competent airgunsmith

[landymick]

I assume the cocking link is fine & going far enough to give the rod sear engagement.

[andrewM]

I have just spoken to Protek. As I am rather out of my depth, I will try to reproduce his views as closely as I can but, basically, he said that there is not enough bite on the sear into the piston. The sear (I gather) seems to be coming far enough back but is not engaging (not engaging the rod?). There is insufficient metal on the piston rod to hold it.

Eeek, does that make sense to you, Ggggr?

Ggggr, I think you spoke to Vic at Protek the other day. He has mended hundreds of rifles and is highly competent but this one has stumped him, somewhat. Would it be possible to give him a call again? I told him I would ask you if you could kindly do so, which he would welcome, as the technicalities are somewhat beyond me. Perhaps a report for other readers could then be provided as I suspect there are some keen followers here of this problem.

If you think you can assist, I see no reason why Vic cannot post the piston and sear to you, as you kindly suggest.

Landymick, I do not understand your question (not being technically minded) but I think your point might be answered above?! I think Ggggr understands the problem, given he has spoken to Protek.

I would really like to get this old rifle working again as it is, otherwise, in great aesthetic condition.

[andrewM]

Thanks Ggggr - very constructive and helpful comments.

You are not treading on Vic's toes; he agreed that I should post the problem on the site last week as, otherwise, I would not have done so. I think it is a challenge to us all and Vic, who is baffled, would welcome a solution as much as I would. It is certainly not straightforward.

Do give him a call, if you are happy to do so - it could be helpful to run your views together. I think this is one of those rare problems where two brains are probably helpful and he spoke well of your earlier call.

[ggggr]

Thanks Ggggr - very constructive and helpful comments.

You are not treading on Vic's toes; he agreed that I should post the problem on the site last week as, otherwise, I would not have done so. I think it is a challenge to us all and Vic, who is baffled, would welcome a solution as much as I would. It is certainly not straightforward.

Do give him a call, if you are happy to do so - it could be helpful to run your views together. I think this is one of those rare problems where two brains are probably helpful and he spoke well of your earlier call.

Andrew----to break this down into simple terms that you should have an idea of, you need to think of what is are the least components that you need to be working before you look at anything else? If you have the trigger block with just the sear and it's pivot, and the rod from the piston, you need these bits to function, as if they don't, then nothing else will. I hope this makes sense? So what you will have done is to have stripped away other things that can cause the problems (coilbound mainspring, bent cocking arm, worn pivots, elongated piston slot, trigger spring, trigger and trigger pivot) . If you can get the sear to engage with the piston rod and to hold (you might be able to keep the pressure on the sear with your fingers or a small piece of wood or alloy), then those components would appear to be ok and then you can add the trigger . The thing that is nagging me is ------does the sear hold the the piston rod ok or not-----------or is the trigger not holding the sear

[andrewM]

Ggggr, you are most kind and tenacious. I understand the gist of what you say albeit I am a rather rare (and recent) collector, I think, in that I have never stripped an air rifle. I have passed on your question to Vic at Protek. There must, surely, be a fault somewhere and, therefore, a solution.

I feel I owe you a very large and generous refreshment but you are rather a distance away!

[andrewM]

Thanks Ggggr! You are not the only one lying awake, grappling with this problem. So is Vic, the good airgunsmith at Protek, and he is no amateur at such things. I gather you very kindly spoke to him earlier today and these are his latest comments, some of which he forgot to convey to you at the time.

"Hello Andrew. Have spoken with GGrrr today. He has given me a couple of ideas to play with. But forgot to tell him the trigger group now fitted came from a good working rifle so problem of trigger/sear/ trigger spring interplay can be discounted. - and the components taken from your rifle work in another rifles trigger block. Have not however tried different pivot screws for components which is something I will try. Also will look at inside walls of block to ensure free movement. Interestingly I also came up with the idea of a fractionally misplaced sear pivot hole which over time with wear and the considerable polishing out that your rifle has had could have caused the failure to cock now experienced. I too have laid in bed pondering it. Usually substitution of all parts would sort it out even if not absolutely certain which specific part was at fault - or most at fault as all parts would have worn equally. Not too much in workshop this weekend so will look at iot once more. Just have to remember to put on the heating a couple of hours before I start, regards, Vic." Unquote.

It seems we are discounting the possible causes, one by one - and barking up a few rare trees at the same time! I am fascinated to know what could be causing the problem.

Rgds
A

[Phil Russell]

OK ... I am coming into this a little 'blind' and you may well have tried / looked at these points; so please excuse me if I am repeating things or suggestions are a load of rubbish:
Have you tried taking detailed measurements of all components to see if and where differences are between working and non working combinations?
Would it help to carefully scribe where triggers lie (i.e. scribe a line on the trigger blade) in the different blocks to look for differences in trigger angle, position etc... are trigger pivot holes in exactly the same position for all blocks? Are trigger - sear angles the same when trigger is assembled in different blocks? If the trigger does not hold on the sear under the spring force then clearly it is slipping so my primitive thought is that the contact angle is not correct, due either to worn angles on the trigger or piston ... again maybe a positional thing. I guess the trigger spring is not binding and restricting trigger movement? I assume trigger pivot is a snug fit and that the piston rod is central and not wobbly?
I am looking forward to hearing of the solution ....
Cheers, Phil