Restoring vintage airguns with Jonathon Young

Gems were once the underdog of the vintage airgun scene, but as Jonathan Young explains, they’re gaining in popularity even if they look a little rough

The Gem was designed in the 1870s in the United States, while this particular example is a later model from Belgium

Not so long ago the best place to find a Gem was in a builder’s skip. Undervalued and overlooked by many, they were certainly interesting air rifles, but only within circles of so-called expert collectors – that’s anoraks to most of us. But an airgun that has lasted for nearly 140 years deserves some respect, and Gems eventually became an affordable alternative to BSAs with their many variations.

The Gem style started from an American design manufactured in Germany. Compared with better finished airguns, Gems have more castings than engineered parts and seem to have been made to an ever decreasing budget with each passing year. Find a really good one today and it’ll be like winning the lottery.

The .25 calibre example seen here, like most of those encountered, has no indication of maker. It’s weary, but this condition passes for acceptable in the world of Gems, and it works very well, unusual for most Gems. This is a large, heavy example at 41.5” long with a full octagonal 23” smoothbore barrel. 

The barrel is held shut by one of two main latch designs. This one is shaped like a letter T, so it’s called a T-bar latch. The other style has a rounded end to the latch, which for the period looked like a porcelain doll’s head, so they called it a doll’s head latch. 

Yep, it’s that simple, with no arguing over batch codes and release dates as with some vintage BSAs.

Today some of these oldies will only drop a pellet three feet from the muzzle, so having to carry out an overhaul is normal. This example was pokey, but the trigger released on its own. Never good! A worn sear would be a real problem with no access to any engineering knowledge. 

Jonathan’s rifle has a T-bar latch, a design dating back to the 1890s, while other Gems had what was known as a doll’s head latch

If you do decide to crack open a Gem, be wary of springs and use protective eyewear.

The cocking arm, which is also the trigger guard, is pinned to the action and held by the shoe within the cocking slot. After being drifted out, a decision was made not to drift the larger barrel pin as the joint was sound and the barrel locked up tightly. 

The trigger and sear fixing pins were drifted out, however, and while the sear was in good condition, a small misshapen trigger spring was found to be the cause of the sear slippage.

The butt is connected to the action by a steel plate screwed to the wrist end. This plate has the spring guide rod and a coarse threaded section to match the cylinder’s threads. The action cylinder is an open channel with a screwed bolt used to pinch the threading channel together. 

The problem is all these threads wear if the small pinch bolt is loose. In a worst-case scenario the butt can eject rearwards over the garden fence. 

On this unit a previous owner had drilled and tapped a discreet fixing through the cylinder wall into the butt assembly. Although not original, it is a superb fix.

This rifle has no seal and virtually no locking threads are left, but while many shooters might discard a gun like this, Jonathan reckons it’s still great!

Undoing the pinch bolt completely opens the tension on the channel threads too much, making it impossible to unscrew the butt under safe control. Instead, it was backed off enough to allow the butt to twist free, and then with the butt held firmly down, the action was unscrewed slowly.

The mainspring was still strong, and after breaking a cautious sweat, the gun came apart. The pinch bolt is a vital safety component on the channel design so it needs to be in good condition. Many are worn and need replacing, which can mean re-cutting a new thread. Now you know why so many have ended up in skips.

Inside, it’s true what they say about Gems not having any leather seals. The pistons were instead honed to the cylinders, and therefore did not need any. The piston head has a milled groove for the sear, which was found to be undamaged. 

Nothing other than a thorough clean with a meths-soaked rag stuck on a wooden dowel was needed. As for the mainspring, these can be a problem if you don’t have a box of old springs to hand, but new springs have recently appeared for sale. 

Luckily this one was in good condition, so was re-used.

The action was reassembled, but it was found near impossible to engage the threads unless the pinch bolt was tightened to near its biting point on the threads, closing the cylinder walls over. 

Here’s a similar Gem showing the atypical open slot channel – that side screw is vital, otherwise everything may fly out backwards
The Gem has a simple rocker trigger, and the right spring is a component that’s far too often overlooked

In reassembly the tapered pins were now found to be a little loose. They were hit gently with a hammer over a vice, deforming them just enough to catch when drifted back into their homes.

The old leather breech seal was replaced with an oversized O-ring. If there is any wear in the main pivot bolt this will show as a wobbly barrel, and a seal made of leather or a fat O-ring can cure most minor wobbles. 

The barrel latch being a metal-to-metal fit can wear, but short of welding on a blob to file back by hand, minor movement on a barrel can be cured with just this seal.

A first test session revealed the new trigger spring was not any good, so a rummage and a refit was tried a couple of times for safety’s sake, with a number of many different micro springs being tried. 

After a run-in, it was time for a chrono test. With a selection of Rhino, Marksman and H&N FTT pellets, the Gem was soon belting these out at nearly nine foot pounds, with sweet, controlled recoil and a very consistent velocity between shots. Now that’s what we call a real Gem. 

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