More BSA Airsporter S

[Kevev]

Hi all,

Following on from my recent post asking for information on my BSA Airsporter S MK1. I have now done a fair bit of research and internet searches prompted by the information and advice I was given in my first post.

I have managed to get hold of the Airgun World magazines that contain the article by Pete Evans on the strip down of an Airsporter Stutzen. While this is a very similar rifle the stock is nothing like what is on my Airsporter S MK1 and it looks like there are other differences in the various sub assemblies. Although I have found the article helpful, I have to admit that I am a little OCD with engineering issues, and although I am a competent mechanical and electrical engineer I like to know exactly how things are before I attempt to take things apart. Consequently, even slight differences confuse me a little.

I have searched on YouTube for videos, but the ones that I can find are not a lot of use to me. When people are stripping these rifles in their videos they are obscuring what I actually want to see with their bodies, or limbs. Most of them show you the rifle and explain what they are going to do and then suddenly move on to 'here it is all taken apart', completely missing out the actual strip down process. Much the same in reverse when it comes to re-assembling everything.

I have also seen a couple of articles about spring tuning kits and I like the upgrade mods like the delryn guides, top hats and slip washers etc. I can see the benefit of these items from an engineering point of view. Once again though there is a little ambiguity in the offerings from suppliers. Some of them list tuning kits for a range of BSA Air rifles, so I am not sure if they would be suitable for my specific model. Others offer a choice of spring, but being a complete novice with air rifle dynamics I am not sure which would be the best choice. In order to find out suitability I have contacted Woodfield-GCP (Welsh Willy) for advice on what would be the best kit, but after about a week and a half since contacting them, I have had no response.

So, here I am again asking for more advice after a week and a half's googling, YouTubing and magazine reading.

I have removed the complete rifle action assembly from the stock and what I can see from the outside looks in excellent condition. the trigger mechanism is greased up and there is nothing to look at that makes me think that A. the gun has had much use, and B. that it has not been stored properly. I will not attempt to strip it down any further until I have got hold of the parts I need to service it. Before I do any further work I have some questions: -

Firstly, in order to change the spring and the piston seals do I have to remove the cocking mechanism? I am assuming that this will not be necessary for just replacing the spring, but for the piston I am not so sure. I suspect that there will be something on the cocking mechanism that engages with the piston? So, can the piston assembly be removed without first removing the cocking mechanism? Bearing in mind that the gun is looking in such good condition, I would rather not disturb anything that does not require attention (that old 'if it isn't broken don't fix it' thing).

Secondly, can anyone recommend the best spring tuning kit from the suppliers out there on the internet, and how do I know it will definitely fit my rifle?

I have seen that Welsh Willy advertises a 'parachute seal', although it says 'Out of Stock'.

Over the last 45 years I have been involved with designing and drawing up mechanical and electrical assemblies for automated food production machinery. One of the most common machines is what is called a filling machine, or depositor. The 'business end' of these machines consist of rotary valves, product cylinders and pistons, with the piston being driven by either pneumatic, or electrical power. They use many stainless, steel, waukesha and delryn parts. The piston seals on these machines range from 3/4" to 4" diameter (with metric equivalents), and have the same type of lipped seal that I have now learnt is known as a 'parachute seal' in the airgun world.

I am certain that once I have the parts stripped and have accurately measured everything, I would be able to make the necessary adaptors and source 'parachute' seals to make this kind of modification myself. I have my own Myford 7 lathe and also have access to larger lathes and milling machines when I need to use them.

One of my other hobbies is classic British motorcycles and I have a few from the 1950's and 1960's. Over the years I have made many parts for them, with great success, and the occasional disaster (which you need sometimes in order to learn). I have always been keen to make parts to improve the performance and usability of the bikes, and would want to apply the same rule to my Airsporter S renovation.

I just need more information, advice and knowledge before I proceed.

Thank you in anticipation.

Kev Ev

[Dornfelderliebe]

Hello Kev.
Although I have no experience of the S models I do know enough about the earlier models to give some advice. I have to remove the cocking assembly. There is one large pin where the cocking lever pivots on the trigger block and I separate the cocking slide connecting link from the cocking slide by removing the smaller pin where the two join. You can then simply jiggle the slide out.

No doubt others can help with the trigger block and the maxi grip rail.

I have fitted three Welsh Willy kits to Airsporter/Mercurys and can vouch that they come pre cut to a length that makes fitting the trigger block much much easier.

Have you looked up Pellets and Pistons on you tube? Because I am certain that I watched one of his videos on a Stutzen which might help you.

ATB DFL

[Kevev]

Hello Kev.
Although I have no experience of the S models I do know enough about the earlier models to give some advice. I have to remove the cocking assembly. There is one large pin where the cocking lever pivots on the trigger block and I separate the cocking slide connecting link from the cocking slide by removing the smaller pin where the two join. You can then simply jiggle the slide out.

No doubt others can help with the trigger block and the maxi grip rail.

I have fitted three Welsh Willy kits to Airsporter/Mercurys and can vouch that they come pre cut to a length that makes fitting the trigger block much much easier.

Have you looked up Pellets and Pistons on you tube? Because I am certain that I watched one of his videos on a Stutzen which might help you.

ATB DFL

Thanks for your response. I have watched the Pellets and Pistons video and it’s a good video on stripping and rebuilding the Stutzen rifle. Unfortunately, as I mentioned, there are many parts in the Stutzen that are very different to the Airsporter S. The trigger unit fits to the barrel with a pin and is not threaded like the The Airsporter, the pellet loader is completely different and the cocking mechanism, although similar, is not the same. Appreciate your response though and the recommendation for the Welsh Willy kit. Just wish I could get a response from him.

[look no hands]

Thanks for your response. I have watched the Pellets and Pistons video and it’s a good video on stripping and rebuilding the Stutzen rifle. Unfortunately, as I mentioned, there are many parts in the Stutzen that are very different to the Airsporter S. The trigger unit fits to the barrel with a pin and is not threaded like the The Airsporter, the pellet loader is completely different and the cocking mechanism, although similar, is not the same. Appreciate your response though and the recommendation for the Welsh Willy kit. Just wish I could get a response from him.

It sounds like the Stutzen video is of a RB2, which like you say is different than the earlier tap loader models, I'd ignore that video, like you say the RB2's trigger block is held in with 3 Allen headed bolts (2 if it doesn't have the maxigrip rail fitted), the earlier ones screw into the cylinder, the piston internals will be different as well, the RB2 is 29mm bore with a parachute seal as fitted to the Supersport/Star, the earlier models are 28mm with the O ring head and buffer washer, the cocking linkage/slide is normally secured to the bottom of the cylinder by a small square metal bracket that goes over the cocking linkage/slide, which has a groove in it, a bolt screws through the square bracket and goes into the groove in the cocking slide, the bolt also acts as the underlever attachment on the short cocking lever models but as you say yours is a mk1 S then it should have the longer lever that attaches to the front of the cocking slide with a catch at the end, in the case of the longer cocking lever model, it will have a thread that screws into the bottom of the cylinder and has a nut that attaches the square bracket to the cylinder, the square bracket should also have threads in them to allow the front stock screws to locate into, you can adjust the bracket with the mounting bolt as its slotted and moving backwards or forwards allows you to adjust it to the stock screw holes, the Stutzen models don't use the front stock screws but utilises a barrel band that attaches through the underside of the front of the stock with a bolt that also becomes a swivel attachment point for a sling.

[Black Beard]

It is years since I stripped mine. You have to remove the cocking mechanism to unscrew the breech/trigger block There may be some plastic washers in there so don't lose them and take pictures of what the pin that holds it together looks like (inside the lever) before you take the pin out. This will ensure you get them the right way around. I think the maxi grip comes off after removing the breech/trigger. The piston probably won't come out with it still on.

[look no hands]

It is years since I stripped mine. You have to remove the cocking mechanism to unscrew the breech/trigger block There may be some plastic washers in there so don't lose them and take pictures of what the pin that holds it together looks like (inside the lever) before you take the pin out. This will ensure you get them the right way around. I think the maxi grip comes off after removing the breech/trigger. The piston probably won't come out with it still on.

You can just tap out the pivot pin (normally a roll pin) that holds the cocking lever to the trigger block and then you can unscrew the block, if it's the RB2 model then you undo the Allen bolts as I described earlier and then undo the grub screw in the bottom of the trigger block between where the cocking lever mounts on and then slide a small alloy plate out for between the block and cylinder, then the trigger block will come out.

[TonyL]

With your background, skill set and workshop facilities available to you, I think you are going to find this very easy, Kev Ev.

The WelshWilly kits are excellent. Being a one-man band and in demand, he might not always be able to respond quickly, though.

The other chap you could talk to would be Tony Wall at Sandwell Field Sports. A font of knowledge. Friendly, happy to dispense advice & tips and able to supply the necessary parts.

[maximus]

For a mk1 Airsporter s, remove the stock, drift out the roll pin that the underlever pivots on, undo the two lock nuts that retain the underlever slide support bracket and remove the underlever assembly. The back block screws into the cylinder but can be tight. Once loosened, I put the muzzle to the floor (protected by an old piston washer or similar, maybe a wooden block with a counterbore to locate the barrel then unscrew. Warning, there can be quite a lot of tension (we call it pre-load) on the spring so make sure you have a strong grip on the back block. Some use a rag to protect their hands but I don't bother. Once unscrewed the spring and guides are lifted out. The piston should also slide out but can be tight if the buffer washer has degraded. I converted one of mine to a Diana parachute seal but it worked just as good with the standard o ring really. The o rings sold to fit the airsporters can be a bit tight so some folks fit a slightly smaller one from the meteor. Quite simple to disassemble, just be wary of the preload on the spring.

[Kevev]

It sounds like the Stutzen video is of a RB2, which like you say is different than the earlier tap loader models, I'd ignore that video, like you say the RB2's trigger block is held in with 3 Allen headed bolts (2 if it doesn't have the maxigrip rail fitted), the earlier ones screw into the cylinder, the piston internals will be different as well, the RB2 is 29mm bore with a parachute seal as fitted to the Supersport/Star, the earlier models are 28mm with the O ring head and buffer washer, the cocking linkage/slide is normally secured to the bottom of the cylinder by a small square metal bracket that goes over the cocking linkage/slide, which has a groove in it, a bolt screws through the square bracket and goes into the groove in the cocking slide, the bolt also acts as the underlever attachment on the short cocking lever models but as you say yours is a mk1 S then it should have the longer lever that attaches to the front of the cocking slide with a catch at the end, in the case of the longer cocking lever model, it will have a thread that screws into the bottom of the cylinder and has a nut that attaches the square bracket to the cylinder, the square bracket should also have threads in them to allow the front stock screws to locate into, you can adjust the bracket with the mounting bolt as its slotted and moving backwards or forwards allows you to adjust it to the stock screw holes, the Stutzen models don't use the front stock screws but utilises a barrel band that attaches through the underside of the front of the stock with a bolt that also becomes a swivel attachment point for a sling.

Thank you, that’s helpful information.

[Kevev]

With your background, skill set and workshop facilities available to you, I think you are going to find this very easy, Kev Ev.

The WelshWilly kits are excellent. Being a one-man band and in demand, he might not always be able to respond quickly, though.

The other chap you could talk to would be Tony Wall at Sandwell Field Sports. A font of knowledge. Friendly, happy to dispense advice & tips and able to supply the necessary parts.

Thanks for the info.

[Kevev]

For a mk1 Airsporter s, remove the stock, drift out the roll pin that the underlever pivots on, undo the two lock nuts that retain the underlever slide support bracket and remove the underlever assembly. The back block screws into the cylinder but can be tight. Once loosened, I put the muzzle to the floor (protected by an old piston washer or similar, maybe a wooden block with a counterbore to locate the barrel then unscrew. Warning, there can be quite a lot of tension (we call it pre-load) on the spring so make sure you have a strong grip on the back block. Some use a rag to protect their hands but I don't bother. Once unscrewed the spring and guides are lifted out. The piston should also slide out but can be tight if the buffer washer has degraded. I converted one of mine to a Diana parachute seal but it worked just as good with the standard o ring really. The o rings sold to fit the airsporters can be a bit tight so some folks fit a slightly smaller one from the meteor. Quite simple to disassemble, just be wary of the preload on the spring.

Thank you, that’s very helpful.

[Kevev]

It is years since I stripped mine. You have to remove the cocking mechanism to unscrew the breech/trigger block There may be some plastic washers in there so don't lose them and take pictures of what the pin that holds it together looks like (inside the lever) before you take the pin out. This will ensure you get them the right way around. I think the maxi grip comes off after removing the breech/trigger. The piston probably won't come out with it still on.

Thank you for your response.

I’m not sure what the ‘maxi grip’ is? I have looked at various parts diagrams, so I can see the part itself and I can’t see anything like it on my Airsporter S. What exactly is the maxigrip? What is its function?

Cheers.

[Dornfelderliebe]

It's a clip on telescopic sight rail which is supposedly difficult to remove. Again my knowledge of the S models is lacking.
Do you have dove tails cut into your cylinder or a rail fixed to it?

Here is a link to it at John Knibbs
https://www.airgunspares.com/catalog.../category/682/

[look no hands]

Thank you for your response.

I’m not sure what the ‘maxi grip’ is? I have looked at various parts diagrams, so I can see the part itself and I can’t see anything like it on my Airsporter S. What exactly is the maxigrip? What is its function?

Cheers.

It was BSA's effort for a positive scope mounting system, you have to buy the right size mounts, which are 13mm to fit the Maxigrip, it is held on the cylinder by three key ways and there us two strips of rubber sandwiched between the rail and the cylinder, this is supposed to reduce the amount of recoil shock to the scope, it is a bit of a pain to get on and off, standard mounts are normally 11mm, which fit the grooves cut In the top of the cylinder, like you will see on yours, they can be a bit shallow sometimes, Sports Match mounts do a special one piece mount that has a reach back facility, so they grip the scope grooves and allow you to mount a scope bit further back over the trigger block, to allow for better eye relief, that all depends of course if you decide to mount a scope and are just sticking with the open sights.

[Kevev]

It's a clip on telescopic sight rail which is supposedly difficult to remove. Again my knowledge of the S models is lacking.
Do you have dove tails cut into your cylinder or a rail fixed to it?

Here is a link to it at John Knibbs
https://www.airgunspares.com/catalog.../category/682/

Thanks for the info.

My rifle had two grooves on the top of the cylinder, not sure I would describe them as dovetails, either side of the Airsporter S logo. They are where the telescopic sight fits. It's a Bushmaster 4x30 scope and came already fitted to the rifle when I acquired it.

I would attach pictures but there is no option to upload them directly. It just gives the option to type in a URL link. My photos are on my PC not on a website. I am on a couple of classic bike forums that are very similar to this one and it is very easy on those forums to upload a photo from my PC. Not sure why it is not that simple here?