Prewar BSA double sear trigger problem

[stevegv8]

Some information here that you may find useful ?

https://forum.vintageairgunsgallery....qs-2/#post-511

Lakey thanks, I was just looking at this for a second time and I see mine is the trigger on the right as I have the rivet (having retrieved every thing from my gun man, will update post further down) but I read this as that version has just one spring? Mine has the recess' to take upper and lower springs, both of which it has, although they are certainly non original as one is cut down with no nice flat and I feel they are too heavy too.
Did they omit one but leave the recess' avoiding a re-design?

Thanks

Steve

[stevegv8]

Ok I can update somewhat now.

Imgur link https://imgur.com/gallery/3JmKJVF shows pics relevant to details in this info.

First of all it's a project that's been waiting a few years and I finally decided while I work on something else, I would send it out to someone I know who claims expertise on the brand.
I had never looked into the guns parts at all but warned him it was supposedly with broken and incorrect parts and was someone's abandoned project and I wouldn't be able to recognise it's problems for myself so handed him a bag of parts.

During the life of this thread I had been thinking two sears would surely require two notches in the piston rod and as the parts were all loose in a bag I was fairly sure the rod had only one notch from memory.

So last night I was dragged out, and went through, Knibbs BSA & LJ air rifles and on page 68 I was able to familiarise myself with how my sear should be, additionally Lakey had show further up the thread the difference between the two types of double sear.
This - if you look through his link https://forum.vintageairgunsgallery....qs-2/#post-511 - suggests, if I understand correctly, that a second spring becomes omitted on my version? the one on the right.
However it did show two notches in the piston rod so my thinking was right and I needed to check this on my one.

So today I went over to get the run down on my fixers findings and now I can see that he meant the rear most sear is missing and the area has been dressed removing any roughness of a break or was it that it purposely removed? I say this because with only one piston rod notch (as I had thought he had missed this detail completely) was the piston changed at some point and they then felt a sear would need to go? it didn't latch up I was told so that's probably where it all had gone wrong maybe. Perhaps it would have done had the front sear been removed? . More importantly is whole the piston correct even?

I felt though that I wanted to take over at this point so I've brought it home for now, It's obvious that taking some time researching was what I should have done in the beginning but as I said I'm into another project at the same time. The spring pic in my link shows wire wheel swarf in the coils which is alarming by whoever is responsible, that area was reassembled when I collected.

I may now have a double sear set up sourced, so next do I need a piston, is it correct but with wrong rod? or do I just need the correct rod or again copy the rod if one can be loaned?

Starting to feel less worried and more intrigued now and enjoying the research although the problem is not yet sorted I'm hoping sorting the piston is the only remaining concern.

Steve.

[Lakey]

Hello,

My guess is that your gun has a later piston fitted with its single notch piston rod. In order to do this , the double safety sear has been adapted, and the second sear ground away.

Lakey.

[stevegv8]

Hello,

My guess is that your gun has a later piston fitted with its single notch piston rod. In order to do this , the double safety sear has been adapted, and the second sear ground away.

Lakey.

That makes some sense and I think that's exactly what's happened, as I mention in the post above, but it doesn't latch after their efforts. Only thing I'd say is the front sear and rod notch both look like they've been re shaped and maybe why it isn't working, the remaining front sear looks quite botched compared with the one in Knibbs picture.

I'm going to put it together without the spring to see how it marries up during cocking but the bit I want to see will be hidden in the trigger block no doubt.

Steve

[edbear2]

Hi Steve,

The reason the pinned one has one spring is that it only needs one, to see what is going on inside it's easy to use the trigger block pivot as a guide and mock up something if you have access to some tube / bit of box. This sort of thing;

https://www.flickr.com/photos/312284...7626485415532/

Or you could maybe make something to hold you action onto a base etc.

Here I set a CD unit on a BSA I modified at the height and position it would be to check sear engagement with a piston rod, so just attach a bit of tube or scrap cylinder to a base, then set up your trigger with a spacer so it's the right height and you will see exactly what is going on as the piston moves back, It is quite enlightening to see how the piston rod ramps over the sear / trigger and then latches when you do this.

The whole double sear system is a rare example of an unnecessary safety (the guns are safe with the tap open) attempt by BSA which was obviously not tested long term, as so many are seen that have been riveted up. When all is good it works well enough, but I doubt guns with the system working get the hard use a gun would have back in the day which obviously brought the problem to light to the dealers / factory.

Pretty much summed up by the fact that the factory "fix" was to disable the whole shebang....The problem getting them to work is also getting the spring balance correct, I have done two or three and it's a pain but can be done (I had a Juvenile which arrived with problems which took ages clipping springs etc. to get the right balance as springs are NLA).


ATB, ED

[stevegv8]

Hi Steve,

The reason the pinned one has one spring is that it only needs one, to see what is going on inside it's easy to use the trigger block pivot as a guide and mock up something if you have access to some tube / bit of box. This sort of thing;

https://www.flickr.com/photos/312284...7626485415532/

Or you could maybe make something to hold you action onto a base etc.

Here I set a CD unit on a BSA I modified at the height and position it would be to check sear engagement with a piston rod, so just attach a bit of tube or scrap cylinder to a base, then set up your trigger with a spacer so it's the right height and you will see exactly what is going on as the piston moves back, It is quite enlightening to see how the piston rod ramps over the sear / trigger and then latches when you do this.

The whole double sear system is a rare example of an unnecessary safety (the guns are safe with the tap open) attempt by BSA which was obviously not tested long term, as so many are seen that have been riveted up. When all is good it works well enough, but I doubt guns with the system working get the hard use a gun would have back in the day which obviously brought the problem to light to the dealers / factory.

Pretty much summed up by the fact that the factory "fix" was to disable the whole shebang....The problem getting them to work is also getting the spring balance correct, I have done two or three and it's a pain but can be done (I had a Juvenile which arrived with problems which took ages clipping springs etc. to get the right balance as springs are NLA).


ATB, ED

Very useful thank you and a really nice job by the way.
Not that it really matters why mine's how it is, but I'm pretty sure now someone needed to change the piston in the past, used a single sear type and ran into issues from doing so then started cutting and shutting getting in deeper to the point it was given up on.
At the end of the day if possible I'd like to return it to how it's life began but happy to convert (properly) to single sear set up if need be. It all hinges on what parts I eventually track down.
I'm not going to restore the finish though, I merely want to get it back to a functioning state.
Right now I'm mainly trying to establish if only the rods differed between the two pistons so a two notch rod can be made to put in this piston or not as I can get a rod made locally otherwise I need a correct piston and sears pair.

Steve

[stevegv8]

The plot thickens as they say.

I have now found since I have all the parts back that my piston is such that it would never have worked in this gun.
I had surmised that it was a replacement (with one notch only it has to be) and a sear was removed expecting to make it work yet didn't work.
Having seen photo's kindly sent to me by Huttles94 my piston and the one from his gun differ in length & design greatly.
My pics should show my one notch piston is much longer and has a skirt extending where Huttles94's does not (would like to know what mine is originally from).

I have learned along the way there were two sears, the two spring type & the later one spring only and rivet (pin) alteration, used in juvenile and Model D's.
So this raises a question in it's self to me though, that being as the cylinder length and bore(?) might differ between two such models then piston length/design might differ between them too. Obviously I must find a particular one notch piston so is there more than one choice?

The only other thing that comes to mind at the moment is how far did they go at solving this? and therefore do I still have the right cocking link?

Huttles94 is kindly sending me a double sear to get me one step closer.

His photo's give me the length info & having pestered him for the piston O/D size I realise as my piston fits the cylinder I already know that, so I will have to post in wanted for the correct piston or loan, of such, a tall order but finding a sear was and Jake had one, top man.

Pic of Huttles94 piston at a fraction over 6 inches and my one at over 7 inches (would normally be a nice brag).

https://imgur.com/gallery/dYwiNRt
Steve

[edbear2]

Yours is the post WW1 extended skirt piston as fitted to the 45" guns, see here at bottom of group;

https://www.flickr.com/photos/312284...7607860743867/


The piston body castings are the same otherwise, it might be you just need to remove the "Skirt" on a lathe........The latch rod however has the notch in a different place, ie. the pre 1919 guns ("sporting" and early standard) were a slightly longer stroke, hence why they often make full power compared to the 1919-39 guns of the same size.

The piston rods can be removed as threaded witha keeper screw.


HTH, ATB, Ed