BSA Airsporter Strip Down

[Kevev]

After getting as much advice as I could from the various, very helpful, members of this forum I attempted to strip my rifle today.

I already had the action removed from the stock, so my first job was to remove the cocking mechanism. This was very straightforward and easy to do. Drifted the roll pin out of the hinge hole on the trigger assembly and then removed the stud at the front and slipped the assembly of the barrel through the keyhole at the front its slot.

Now I’m stuck because I cannot shift the trigger mechanism from the barrel. I’m assuming it’s a right hand thread, so I turned a 1/2” diameter spigot on a length of 16mm diameter stainless round bar. That was a very snug fit in the large hole in the trigger mechanism. I then put the barrel in the soft jaws of a large bench vice and, with the bar in the hole, gave it a sharp whack in an anti-clockwise direction. Not a sign of any movement. Several ‘whacks’ later and holding it as tight as I dare in the vice (not wanting to distort anything on the barrel, I cannot get the thing to move.

Any suggestions anyone?

Cheers,

Kev

[Airsporter1st]

After getting as much advice as I could from the various, very helpful, members of this forum I attempted to strip my rifle today.

I already had the action removed from the stock, so my first job was to remove the cocking mechanism. This was very straightforward and easy to do. Drifted the roll pin out of the hinge hole on the trigger assembly and then removed the stud at the front and slipped the assembly of the barrel through the keyhole at the front its slot.

Now I’m stuck because I cannot shift the trigger mechanism from the barrel. I’m assuming it’s a right hand thread, so I turned a 1/2” diameter spigot on a length of 16mm diameter stainless round bar. That was a very snug fit in the large hole in the trigger mechanism. I then put the barrel in the soft jaws of a large bench vice and, with the bar in the hole, gave it a sharp whack in an anti-clockwise direction. Not a sign of any movement. Several ‘whacks’ later and holding it as tight as I dare in the vice (not wanting to distort anything on the barrel, I cannot get the thing to move.

Any suggestions anyone?

Cheers,

Kev

Try applying some heat with a heat gun.

[Dornfelderliebe]

Welcome to the world of the seized up trigger block.
I recently had a badly stuck Mercury and my Mk6 bought new and a Mk1 Airporters were also stuck fast.

I used repeated cycles of heating and cooling over a couple of days and tried to get easing oil to the threads from inside the cocking slot leaving it to soak overnight.
I only had the wife's hairdryer and was never sure whether the heat would conduct to the block's thread. The block does turn anti clockwise to loosen and a rod through that hole is what others use to turn it.

Give it time and every so often clamp your trigger block in the vice and try to turn the whole action with both hands. Just when I was beginning to despair with the Mercury I tried that and it popped straight off.

[Kevev]

Welcome to the world of the seized up trigger block.
I recently had a badly stuck Mercury and my Mk6 bought new and a Mk1 Airporters were also stuck fast.

I used repeated cycles of heating and cooling over a couple of days and tried to get easing oil to the threads from inside the cocking slot leaving it to soak overnight.
I only had the wife's hairdryer and was never sure whether the heat would conduct to the block's thread. The block does turn anti clockwise to loosen and a rod through that hole is what others use to turn it.

Give it time and every so often clamp your trigger block in the vice and try to turn the whole action with both hands. Just when I was beginning to despair with the Mercury I tried that and it popped straight off.

Thank you, and to Airsporter1st, for your response.

I am going to put the barrel in a lathe with a self centring 4 jaw chuck on Wednesday, as I think that will hold it better than the vice. Will try some heat with a heat gun and see how it goes.

Do you have any idea, how much force the barrels will take for holding them? I think the 4 jaw will have less chance of distorting anything as the pressure will be applied much more evenly.

Cheers,

Kev Ev

[Dornfelderliebe]

I don't know but I would be gentle. I cut one inch off the counter bored section of a Meteor barrel ( leaving 1/4 inch) and was surprised how easily it cut with junior hacksaw.

[SRV1]

On many Mercury's and Airsporter difficult to unscrew trigger blocks, I have used a small gas torch heating and rotataing the cylinder very quickly where the block screws in, it will be hotter than a heat gun or hair dryer!

The heat has never destroyed or discoloured the bluing - but, be sensible about it, no not cherry red!

Before unscewing, with a steel rule and scriber I will make two small alignment marks between the flat section on the trigger block and cylinder. The marks at the bottom will not be seen as the stock covers them up. Hell, the total length of this witness scribe is only about 3/16's of an inch. Hoping the last fitting was aligned!

Before heating, I wrap several turns of masking tape around the flats of the trigger block and a fair whack with a hide mallet always goes the business, the tape also stops the pins dropping out, they sometimes fear the blow with the mallet....

I also do a bit of cheating when screwing the trigger block in, if it very tight within a couple of degrees or so of alignment, rather than faff about with the hex nut that enables adjustment, I use a wide smooth flat file and take a very light dressing off the cylinder - be sensible, keep it square. No, no not an angle grinder please!

Before final fitting, copper coat the threads and check that the hex nut is tight, otherwise, the swear bow would be full in no time should it be loose.

Kind regards to all.

[crowbar]

I use a split hardwood bush that fits the O/D of the comp tube and clamp the bush in the vice and wack the trigger block with a dead blow mallet , if you use the lathe a 3 jaw chuck and a split bush out of aluminium tube can be used .

[Kevev]

On many Mercury's and Airsporter difficult to unscrew trigger blocks, I have used a small gas torch heating and rotataing the cylinder very quickly where the block screws in, it will be hotter than a heat gun or hair dryer!

The heat has never destroyed or discoloured the bluing - but, be sensible about it, no not cherry red!

Before unscewing, with a steel rule and scriber I will make two small alignment marks between the flat section on the trigger block and cylinder. The marks at the bottom will not be seen as the stock covers them up. Hell, the total length of this witness scribe is only about 3/16's of an inch. Hoping the last fitting was aligned!

Before heating, I wrap several turns of masking tape around the flats of the trigger block and a fair whack with a hide mallet always goes the business, the tape also stops the pins dropping out, they sometimes fear the blow with the mallet....

I also do a bit of cheating when screwing the trigger block in, if it very tight within a couple of degrees or so of alignment, rather than faff about with the hex nut that enables adjustment, I use a wide smooth flat file and take a very light dressing off the cylinder - be sensible, keep it square. No, no not an angle grinder please!

Before final fitting, copper coat the threads and check that the hex nut is tight, otherwise, the swear bow would be full in no time should it be loose.

Kind regards to all.

Thanks for that, a very comprehensive explanation. Much appreciated. 👍🏻

[TonyL]

Nothing to add, really; some good advice up above. I did have a Mercury that was perticularly stubborn once, but it came off in the end. Heat may well have made things easier. I'd always tape those trigger pins up to stop them falling out. Scribe marks to help with re-alignment, yes, but you can easily kinda gauge it anyway. And I always clean those threads up once the gun is stripped and lightly grease upon re-build to assist future maintenance.

Hope all goes well.

[Dornfelderliebe]

Just a point of order but your Mercury with it's paint finish won't look very nice if you use a blow torch on it.

[look no hands]

Just a point of order but your Mercury with it's paint finish won't look very nice if you use a blow torch on it.

That goes for the Airsporter as well with the painted trigger block.

[Dornfelderliebe]

That goes for the Airsporter as well with the painted trigger block.

I'll stick to incurring the wife's displeasure.

[Kevev]

That goes for the Airsporter as well with the painted trigger block.

Hi there, I managed to get the trigger block off this morning. I put the barrel in a self-centring 4 jaw chuck and used my heat gun to heat the barrel a little. One sharp hit on my spigoted bar, placed in the trigger block hole, and it was on its way.

I managed to get the barrel unscrewed from it with a folded up towel over the end of the trigger block and supporting that on my chest as I leant over it.

Getting the piston assembly out of the barrel was relatively easy and, as I had been warned to expect, the buffer washer was very eroded and just crumbled into pieces. Getting the piston pin drifted out was very difficult and I had to resort to butchering the piston a bit to achieve it. Leaving me with a battered piston and a bent and butchered pin. Fortunately these parts are available, so I will invest in new ones. Is it usually so hard to get the piston pin out? I measured the outside diameter of the pin and it is 2.38mm (I guess it was made in imperial sizing and is a 3/32" pin). The hole in the rod of the assembly it fits to is much larger, I haven't had the chance to measure it accurately yet but it looks to be getting on for 4mm (5/32"?). Is this normal?

Also can you tell me anything about the pellet loading mechanism. I had to take off the lever to get the barrel in the lathe chuck and to do this I just removed the screw and lifted the lever away from the rotating barrel it was fastened and keyed to. I don't know if something happened when I gave the trigger block a whack but when I screwed the lever back on it didn't seem right and I found that I could pull the loading barrel out towards the lever side. It did not seem to be positively located. I took it completely out of the rifle barrel and all I have is the loading barrel, a spring and ball and the lever and its fixing screw. Am I missing something? When I look at the exploded diagram on the TW Chambers web site there is something that looks like a washer on the opposite side of the lever. I don't appear to have this part. Any info on the loading mechanism would be greatly appreciated.

Cheers,

Kev Ev

[look no hands]

Hi there, I managed to get the trigger block off this morning. I put the barrel in a self-centring 4 jaw chuck and used my heat gun to heat the barrel a little. One sharp hit on my spigoted bar, placed in the trigger block hole, and it was on its way.

I managed to get the barrel unscrewed from it with a folded up towel over the end of the trigger block and supporting that on my chest as I leant over it.

Getting the piston assembly out of the barrel was relatively easy and, as I had been warned to expect, the buffer washer was very eroded and just crumbled into pieces. Getting the piston pin drifted out was very difficult and I had to resort to butchering the piston a bit to achieve it. Leaving me with a battered piston and a bent and butchered pin. Fortunately these parts are available, so I will invest in new ones. Is it usually so hard to get the piston pin out? I measured the outside diameter of the pin and it is 2.38mm (I guess it was made in imperial sizing and is a 3/32" pin). The hole in the rod of the assembly it fits to is much larger, I haven't had the chance to measure it accurately yet but it looks to be getting on for 4mm (5/32"?). Is this normal?

Also can you tell me anything about the pellet loading mechanism. I had to take off the lever to get the barrel in the lathe chuck and to do this I just removed the screw and lifted the lever away from the rotating barrel it was fastened and keyed to. I don't know if something happened when I gave the trigger block a whack but when I screwed the lever back on it didn't seem right and I found that I could pull the loading barrel out towards the lever side. It did not seem to be positively located. I took it completely out of the rifle barrel and all I have is the loading barrel, a spring and ball and the lever and its fixing screw. Am I missing something? When I look at the exploded diagram on the TW Chambers web site there is something that looks like a washer on the opposite side of the lever. I don't appear to have this part. Any info on the loading mechanism would be greatly appreciated.

Cheers,

Kev Ev

The hole in the piston rod is normally about the size you say, the buffer washer is normally thicker, so puts pressure on the piston head when the pin is located through the piston rod and piston head, you may need to push the piston head onto the piston rod to get the pin in, obviously the pressure from the buffer washer against the head stops the pin from coming out, although some heads have the pin go through the outside of the head and some locate in the groove the O ring sits in and the O ring also stops the pin from falling out, if I'm honest I'm not completely clued up on the loading taps, I've only ever taken one apart and that was many moons ago, I normally just deal with the Mercury now, like already mentioned, have a look at the nut than holds the threaded cup to the alloy trigger block as they can come loose, if they do then your trigger block will spin and not undo from the cylinder, you will need a thin walled socket (I think its a 17mm?) or box spanner, if you find the trigger block doesn't line up properly with the cocking slot after reassembly then you may need to undo the nut and spin the block a tad to get things realigned and then do the nut back up.

[Kevev]

The hole in the piston rod is normally about the size you say, the buffer washer is normally thicker, so puts pressure on the piston head when the pin is located through the piston rod and piston head, you may need to push the piston head onto the piston rod to get the pin in, obviously the pressure from the buffer washer against the head stops the pin from coming out, although some heads have the pin go through the outside of the head and some locate in the groove the O ring sits in and the O ring also stops the pin from falling out, if I'm honest I'm not completely clued up on the loading taps, I've only ever taken one apart and that was many moons ago, I normally just deal with the Mercury now, like already mentioned, have a look at the nut than holds the threaded cup to the alloy trigger block as they can come loose, if they do then your trigger block will spin and not undo from the cylinder, you will need a thin walled socket (I think its a 17mm?) or box spanner, if you find the trigger block doesn't line up properly with the cocking slot after reassembly then you may need to undo the nut and spin the block a tad to get things realigned and then do the nut back up.

Thanks again, I've been looking at things and I think I have found what keeps the loading mechanism in position. There are a couple of recessed areas machined into the stock and when the action is bolted in they do the job of retaining the loading tap, as you refer to it. I didn't know what it was 'officially' called but tap seems to describe it well. So the stock keeps it in the barrel and the indent ball and spring will positively position it when it is turned to the shooting position. At least that is how it looks to me and I cannot see it being any other way. Most of the Airsporters I have seen in videos appear to have a tap where the lever and cylinder (the part with the pellet hole in it) are one unit and there is a screw and indexing washer on the opposite side of the lever.
On my rifle, which is the S model the lever comes away from the cylinder, The cylinder has an indexing key machined in the lever end and the lever has the corresponding mating key machined into it.

The 3/32" hole in my piston is behind the O-ring groove. If the new pin I have ordered is anywhere near as tight as the original that I removed then there is no way it is going to come out without being attacked with a pin punch and a hammer

Cheers,

Kev