Leather seals…

Some time ago I decided to try to make some new leather seals for a 1925 Anson Firefly and a 1925 Frank Clarke Briton. The seals in the Briton were almost non-existent. They hadn’t been cared for and were crumbling to pieces. The seals on the Firefly had worn out around the barrel and so it had little to no power.

The seals for both pistols are simple flat discs with a hole in the center for the barrel. On some airguns, the seals are cup-shaped. Both pistols have two seals each. The Firefly seals are about 5 mm by 1-inch and the Briton seals are about 4mm by half an inch or thereabouts.

First of all, I needed some leather. A quick search on eBay and I found some 4mm by 2-inch wide natural veg tan leather belt blanks that appeared to be suitable. A few days later it arrived.

I knew the tricky part would be cutting a disc out of the leather and also making a hole for the barrel that was exactly central. If the hole was out even by a small amount, it would never make a good seal around the compression tube. I have used hole punches in the past but the problem with these is that it is all but impossible to line up the second punch after the central hole is cut or vice versa. The easiest solution would be to make both cuts at the same time. I thought I would give a hole cutter a try as I have used these before to make the circular holes in foam inserts for pistol cases.

I had a selection of hole cutters already but none that were just the right size or even close. A quick trip to my local hardware shop soon solved that problem. Faithfull has a range of hole cutters that are used with an arbor or mandrel (a drill that is screwed onto the hole cutter). I selected a couple of hole cutters that were just slightly bigger than the existing seals. This would at least solve the problem of aligning the hole for the barrel centrally on the disc. I wasn’t too sure whether it would produce a good cut though. But it was worth a punt I thought.

I set-up my bench-top pillar drill with the hole cutter and arbor and a block of wood as a stop. With the pillar drill set to a high speed, I cut a disc out of the leather sheet. Normally, a hole cutter is used to cut just a hole. But in this case, the waste material or the piece that is removed from the leather would be used as the seal. It was important to select a hole cutter with an internal diameter that is slightly bigger than the finished seal. The leather cut surprisingly well and left only some frayed edges at the bottom of the cut. These were trimmed off easily with a sharp knife.

I found a 30mm hole cutter that gave exact sized discs for the Firefly but I had selected the wrong size for the Briton. I had anticipated that all the seals would be slightly too large as it would be better for them to be too big than too small. For the Briton seals, I mounted them onto a bolt with washers on either side and held them in place with a nut. The whole assembly was placed into the chuck of the pillar drill which would become a makeshift lathe. A flat file was used to gently file down the leather disc until it was a snug fit in the tube of the pistol. Slowly and gently is the key here. You only want to take a small amount off at a time and you don’t want to put too much stress on the bearings of the pillar drill as it isn’t built for side pressure. It’s important to use a bolt that fits the hole perfectly. If it is too small, the leather disc may not be central or it could move under pressure and the result will be oval-shaped.

Once the disc was just the right fit, the barrel hole needed to be opened up to the correct size. Using sharp wood drills I progressively opened up the hole until it was just right. Again, this needs to be a snug fit around the barrel or the pistol will lose compression. Where necessary, I used a round file to make the hole just that little bit larger.

At this point, the new seals look quite rough – even after trimming! Whereas the old seals look square and smooth. However, this is remedied in the final step of the process – a good soaking in oil. Not just any oil though, but Neatsfoot oil. Traditionally, neatsfoot oil was used to deeply penetrate and soften leather. It has been used since the 18th century and is made from the shin bones and feet of cattle. The word “neat” originating from an old English word for cattle. You can buy Neatsfoot oil from your local tack shop. A half-litre tin typically costs about £5 or £6 whereas some gun shops sell as little as 10 ml for £1.50. I dare say the 500ml tin I bought will last longer than I will!

All that’s needed is to soak the seals in a tub of Neatsfoot oil overnight. It’s surprising how well it penetrates the leather and softens it up. I used a tub with a lid to prevent spills but also so that I could reuse the oil the next time I need to make more seals. Before you fit the seals, wipe off the excess oil with a rag or kitchen roll. Don’t use toilet paper… that leaves fluff whereas kitchen roll doesn’t.

Once fitted into the pistol, the seals smooth themselves out against the walls of the compression cylinder forming a good airtight seal.

One last step… checking the performance! At the time of writing, I have only completed the Briton. The seals for the Firefly are still in the soak tank/tub. However, the Briton worked impeccably. I generally test dart firing pop-out pistols by firing at a corkboard. The Briton embedded the darts right up to the hilt into the board. Job’s a good’un I think!

It’s so uplifting to bring these early air pistols back to full working condition. No doubt I shall have some fun with my young lad during these dark winter evenings with a game of air pistol darts. There are most likely other ways to make leather seals. Hopefully, my method might help you to make some to revive your airguns to their former glory.