Bsa buffer washer cheese period?

[Hsing-ee]

How long does it take for a BSA Airsporter or BSA Mercury buffer washer take to turn to cheese and jam the piston in the cylinder? Five year? Ten? Twenty?

Just replacing one so need to know the service interval... or best just to put at new one in at spring renewal?

[Dornfelderliebe]

How long does it take for a BSA Airsporter or BSA Mercury buffer washer take to turn to cheese and jam the piston in the cylinder? Five year? Ten? Twenty?

Just replacing one so need to know the service interval... or best just to put at new one in at spring renewal?

My Meteor and Airsporter went 20 years without jamming up. However I don't know how long they'd been cheese.

[Benelli B76]

If it is the modern polyurethane it should not deteriorate as it will contain a special additive in the mix which did not exist in the old type.
In all the many Meteors I have fixed I just fit a large rubber tap seal which is the correct diameter and just needs the hole opening to 10 mm.

Baz

[Tinram]

Totally agree with previous comment. I’ve rescued loads of BSA’s from the 60’s/70’s with jammed pistons. The replacement buffer washers sold these days are so much better. Just about anything you replace them with now , would be better than what BSA used back in those days!!

[4end]

Firstly I would ask as to why this washer needs replacement as it is different to most springers that have the piston seal affixed directly to the end of the piston and therefore may not be necessary.
Some years ago I removed the buffer washer off a Mercury, same system, and it made no difference to its functioning other than raising the amount of air as swept volume, it also increased energy slightly and reduced felt recoil.

[Tinram]

Personal choice really with respect to piston heads on these BSA’s. There’s quite a few alternatives eg bolt on parachute style heads etc. I’ve experimented with a few over the years and have a mixture of “original” heads & non - standard ones on some of my BSA’s.
It’s not the only factor of course, and it’s relatively easy to change them & judge the differences.

[Shed tuner]

D28 parachute seal; enjoy the extra stroke/power/efficiency/smoothness

[Hsing-ee]

D28 parachute seal; enjoy the extra stroke/power/efficiency/smoothness

Subject is an excellent condition late model Mercury Mk 4, not the S, but with the breech bolt and rolled on chequering and a nice stock.

I want to see what it will do in standard fettle before thinking about modifying it, some collector probably deserves it more than me.

I do have a spare piston for experimentation later down the road should I choose to go that way.

The cheese-drag seems to have buggered up the shot cycle and it was only grouping 1" at 10 yards, which I would expect from a pistol on a rest.

Strangely the cheese seemed to autofragment and then jam between the piston head and the cylinder; I was not expecting it to be a problem as the rifle appeared well looked after but the sawdust-like fragments of cheese were apparent around the cocking slot and I opened it up to find total dissolution of the cheese buffer. Weird. I think this was simply an age thing, rifle must never have been opened and it must be 35 years old, just doesn't look it. Because of my age it seems a 'contemporary' rifle but that is so so wrong. No Mercury has left the BSA factory in a generation.

[Hsing-ee]

Firstly I would ask as to why this washer needs replacement as it is different to most springers that have the piston seal affixed directly to the end of the piston and therefore may not be necessary.
Some years ago I removed the buffer washer off a Mercury, same system, and it made no difference to its functioning other than raising the amount of air as swept volume, it also increased energy slightly and reduced felt recoil.

I've no idea. The piston head on some Mercury's and Airsporters was nylon, and some aluminium as well as a heavy steel one. Perhaps it was to mitigate against dry-firing as young British boys are want to do. The Meteor has quite a sturdy piston head so not sure what that was about either. Maybe a USP; certainly using 'O'-rings and a rubber buffer was pretty radical for the time, most (except FWB Sport) still using leather washers. I remember the Mercury getting very consistent velocities when up against its contemporaries.

[gunshop]

I've no idea. The piston head on some Mercury's and Airsporters was nylon, and some aluminium as well as a heavy steel one. Perhaps it was to mitigate against dry-firing as young British boys are want to do. The Meteor has quite a sturdy piston head so not sure what that was about either. Maybe a USP; certainly using 'O'-rings and a rubber buffer was pretty radical for the time, most (except FWB Sport) still using leather washers. I remember the Mercury getting very consistent velocities when up against its contemporaries.

The Plastic Piston head was an effort by BSA to cut costs, the worse mistake they ever made. The alloy one is the standard piston head and the steel one was classed as the Export version.

[Dornfelderliebe]

Firstly I would ask as to why this washer needs replacement as it is different to most springers that have the piston seal affixed directly to the end of the piston and therefore may not be necessary.
Some years ago I removed the buffer washer off a Mercury, same system, and it made no difference to its functioning other than raising the amount of air as swept volume, it also increased energy slightly and reduced felt recoil.

It's common to remove the buffer washer on a Mercury/airsporter but then you have to drill a new hole for the retaining pin and probably shorten the spigot. I cannot see how you can remove the buffer washer on a key way head on the Meteor without making so much play that it rattles about on the piston.
Some aftermarket heads are fixed with a nut where you probably, can remove the washer, with the benefits above.

[greenwayjames]

I've no idea. The piston head on some Mercury's and Airsporters was nylon, and some aluminium as well as a heavy steel one. Perhaps it was to mitigate against dry-firing as young British boys are want to do. The Meteor has quite a sturdy piston head so not sure what that was about either. Maybe a USP; certainly using 'O'-rings and a rubber buffer was pretty radical for the time, most (except FWB Sport) still using leather washers. I remember the Mercury getting very consistent velocities when up against its contemporaries.

The problem with using nylon as a material for apiston head is that it absorbs moisture and swells causing the piston to jam in the cylinder as many BSA Mercury and Airsporter owners have found out.
When JB designed and developed the first conventional pcp for BSA, the Hornet, he used Delrin to make the hammer with a steel core so that it did not require lubrication which can cause inconsistency. BSA used local small subcontractors who knew that there were no quality control checks on the components. For whatever their reason instead of using Delrin or acetal the subcontractor used nylon for the hammer body. These were fitted into the Hornets and a few months later rifles were returned under warranty complaining of inconsistency shot to shot, sticky and even jammed solid hammers. Result, ruined reputation.
More about this on the Facebook Official JB fanpage.

[Tinram]

It's common to remove the buffer washer on a Mercury/airsporter but then you have to drill a new hole for the retaining pin and probably shorten the spigot. I cannot see how you can remove the buffer washer on a key way head on the Meteor without making so much play that it rattles about on the piston.
Some aftermarket heads are fixed with a nut where you probably, can remove the washer, with the benefits above.

The after market ones (eg Welsh Willy) bolt/nut work a treat on keyhole piston Meteors. I’ve done three now with accompanying parachute seals instead of the old O ring. Shooting fine👍

[gunshop]

It's common to remove the buffer washer on a Mercury/airsporter but then you have to drill a new hole for the retaining pin and probably shorten the spigot. I cannot see how you can remove the buffer washer on a key way head on the Meteor without making so much play that it rattles about on the piston.
Some aftermarket heads are fixed with a nut where you probably, can remove the washer, with the benefits above.

We make a version that takes the original O-ring and buffer washer on a nut for the Meteors

https://www.airgunspares.com/162194j...onheadjki.html

[Hsing-ee]

Stripped the Mercury, there was resinous buffer cheese lacquering the compression chamber and it would not come off until I hit it with the Solvol Autosol and an electric drill.

The spring seemed very straight, there is a ridiculous about of pre-load on these guns and it was a total bastard to get the spring back in, even with the assistance of a spring compressor.

As a result of this I do not like this gun. The cocking effort is quite high, I am not sure if the spring is a Titan or something OTT but I will take it for accuracy testing tomorrow and run in the Meteor 'O' - ring.

While it comes up to the aim brilliantly, and looks like a swoopy beauty, I just keep thinking the HW35 is the better choice of the era.