How To Change Breech Seal Air Rifle

Simon Everett shows how easy it is to replace a breech seal, even a vintage leather item, animate new life into a much-cherished burglarize.

Replacing the breech seal on a vintage rifle like this Buck simply requires a few basic tools – but the job is far easier if yous have a means to concord information technology stable

Leather has been used every bit a sealing textile in all sorts of applications e'er since the beginnings of engineering. Leather is a remarkable material. It has slight elastic qualities, is hard wearing, flexible and is also easily worked into required shapes.

It was these backdrop of leather that permitted the gunsmiths of the continent to make the very first pressurised airguns equally far dorsum every bit the late 1500s, and there is a bellows airgun from 1580 in the Livrustkammaren museum in Stockholm.

Leather provided the means for gunsmiths to create a seal that would be tight enough to make an airgun work effectively – and also to fill the bellows to fire the forges that would allow them to oestrus the metal to be worked at high temperatures.

Leather seals for both the piston and the breech were still in common use for airguns upwardly until the 1970s when synthetic materials took over. In that location are many airguns still in apply that use leather for their seals, such as this BSA Cadet from 1947.

The quondam seal had perished later on years of apply and was no longer making annihilation like a reliable airtight seal

Equally you tin see, the original part had shrunk and was not making any kind of seal whatsoever. Shooting over the chrono gave a variable event betwixt 2.6 and 3.iv foot pounds.

Over the years a leather seal volition habiliment out, dry out and crack unless information technology's treated with an inert oil. Any seal, leather or synthetic, will need renewing, as the repeated expansion and compression from opening and endmost the barrel gradually wears out the seal.

Fortunately, irresolute the seal is a fairly straightforward job that the majority of airgun shooters can tackle themselves with the almost basic of tools.

It makes sense to get everything together earlier starting. You will need a screwdriver and something to assistance wheedle out the old seal. I used a bearing seal picker and snipe-nosed pliers.

You'll likewise need some inert oil. Neatsfoot oil is my preference for leather, but something similar Parker-Hale Limited Gun Oil does piece of work, and is what I had to hand. A clean rag is a skilful idea to wipe surfaces too as your easily. And finally, you'll need a suitable replacement seal.

Information technology isn't strictly necessary to have a bench vice, just it does help profoundly by freeing upward your hands and then you tin can piece of work more accurately, safely and efficiently. My vice is portable, and information technology was perfectly adequate just sitting on a garden tabular array assuasive me to piece of work exterior in the sunshine.

I made some soft jaws from folded corrugated cardboard that I cut from a box, in order to protect both the wood and metal parts of the rifle whilst gripped gently in the vice. Be careful not to overtighten the vice and crevice the stock.

When taking off whatever type of gun stock, identify the screws you'll need to remove and the tools you'll crave to practise information technology

This stock on this particular rifle is held in place by two screws in the forend and ane at the base of the trigger guard

With the stock screws removed the woodwork and metalwork can and then be parted – who knows when this Cadet was last seen naked?

Existence a rifle of relatively low power, no spring compressor is needed and the end cap tin be unscrewed by hand

The leap and guide can now be removed, making the burglarize completely inert and totally safe to work on

Simon's side by side chore was to clamp the action at the cocking block in order to hold the butt notwithstanding

A bearing seal picker is the ideal tool to use to dig out the old seal as it has the required caste of finesse

What's left of the erstwhile leather washer tin can then exist carefully pulled out with a pair of snipe-nosed pliers

Replacement seals can be made from a variety of suitable materials, but Simon chose leather to retain the integrity of this 1947 classic

Simon cleaned out any remaining detritus from the seal groove with a wooden cocktail stick earlier plumbing fixtures the new seal

He pressed the new seal into identify with his fingers, carefully working around the edge to maintain the correct shape

The leather seal was then gently tapped fully home, with Simon using the handle of his screwdriver rather than a mallet

At this stage the new seal was continuing proud and had to be carefully trimmed downward

Simon repeatedly airtight the barrel to check the fit, trimming off a little more leather if the seal was still standing too proud

The washer itself showed Simon where he needed to trim, taking care to cutting away but a little at a time

Simon put a couple of drops of oil onto the leather seal to swell it, merely only after it had been properly seated and trimmed to fit

With the rifle held snugly, the beginning job is to separate the wooden stock from the metallic workings. Using a properly fitting screwdriver, disengage the stock mounting screws, typically ii at the forend and 1 at the rear of the trigger guard.

That is all that holds the gun into the stock, and then be ready for the cylinder and barrel to come loose and possibly fall out. I used an old water ice cream tub to concord the parts every bit I removed them.

On these early BSAs, dismantling is a very simple job. The sloped end cap only unscrews by hand, there is very footling preload on the spring, so whilst there is some pressure from it when the final thread is released, it isn't stiff enough to worry near provided you lot are prepared for it. With the terminate cap unscrewed, the spring and spring guide can be lifted out entirely. Place them carefully in the tub together with the finish cap.

Now there is no longer any tension on the barrel, you can reclamp the gun by the cocking lever and the attachment for it below the barrel. This will allow you lot to work on picking out the old seal with the barrel held firmly.

I used the begetting seal picker to carefully dig out parts of the one-time seal until enough fabric had been lifted out of the groove so it could be gripped
with my snipe-nosed pliers and pulled costless. I and then cleaned out the seating groove around with a wooden cocktail stick and blew off whatever residual bits of the old seal.

Now comes the interesting role – fitting the new seal. I had a small selection of seals of diverse sizes to cull from. I wanted to stick with leather to keep the Cadet as original equally possible, and then I offered the two I had up and went with the smaller one equally it looked the closest to the dimensions of the barrel and seal groove.

With the internal circumference of the leather seal placed carefully around the barrel, I pressed the seal with my fingers to start working it into the groove. Information technology is very important to do this job while the seal is still dry.

Then I gently tapped the seal with the handle of my screwdriver to knock it home, bit by bit, continually reshaping the leather as I went. It was a case of a bit of borer, a chip of shaping, then a fleck more tapping and a bit more shaping. Gradually the seal worked its way into the depth of the groove. I have never understood why the breech seal groove is so deep, unless it allows extra elasticity and resilience within the seal.

With the new seal tapped fully home, information technology was way too proud to allow the butt to shut, fifty-fifty though the top of it had been compressed. So it needed a bit of shaping to end it off, and this was done past trial and error, shaping it and trimming information technology piddling by niggling. It is not a precise science.

Using a very sharp knife, I removed a slice across the top and then closed the barrel to check for fit. Gradually, sliver past sliver, I trimmed the seal to fit. Some people advocate using a big washer that fits over the seal to act as a cut guide and I have no doubt this was probably the method used in the manufactory to speed upward the process and produce a uniform-fitting seal, but I had to go past eye and just take my time.

Once the butt would close properly without too tight a fit, I put a drop of oil on the seal, and with the butt open allowed information technology to soak overnight. The following day the seal had completely soaked up the oil, so I put another drop on the reverse side and left it to soak for another 12 hours.

At the end of this time I had a seal that looked pretty expert. It was a piddling fleck proud of the breech and the barrel closed snugly each time. Putting the rifle over the chrono it was at present producing between 5.8 and half dozen.2 ft-lb and hopefully will requite a few more than years of fun. Job done!