|Mk I BSA Airsporter, bloody sexy.|
The Airsporter is a tap loading underlever spring piston air rifle, and the awesome thing about the underlever part is that it is hidden from view in the underside of the stock, making it look like a sporting firearm rifle. The BSA Mercury is a break barrel that is identical in looks, but was not introduced until the MkI in 1971, by which time the Airsporter was at it's MkV stage. Even the old BSA Cadet has similar looks, though is a totally different design. They all have the smooth swept back look from the rear of the piston cylinder to the comb of the stock, instead of a step.
|.22 BSA Mercury with scope, .22 BSA Airsporter and a .177 BSA Cadet, sharing a common heritage.|
The big thing to remember about old BSA air rifles is that the bore of the .22 was actually 5.6 mm and not 5.5 mm, so they tend to be very pellet fussy when looking for both power and accuracy. Old Eley Wasps worked well but not the new ones, however RWS Superdomes tend to fare well in my experience.
The front sight has four interchangeable elements of different heights with a bead on top. The sight element is secured with a small screw from the left hand side. This sits atop a sloped ramp with a hood around it, though in this case there is no hood and just one of the taller elements.
|Beaded sight elements come in low, standard, medium and high and are secured with a small screw.|
The rear sight is of a leaf or butterfly design that flips up and down and sits in a dovetail in a sleeve around the barrel, just in front of the loading port. The unit is drifted in the dovetail for horizontal sight correction.
|Rear leaf sights using the V notch at the moment.|
A small notched plate secured by two small screws sits between the leaves and has a small amount of vertical adjustment, it can also be fitted upside down giving you the choice of a V or U notch to sight with.
The other option is to fit a scope, which can be done. The piston cylinder has two sets of short scope rails each set 13mm wide, this means a scope will be a little off centre with modern mounts but adapters or special mounts can be bought.
|Early, rudimenary scope rails, better than nothing but still a bitch to fit modern mounts on.|
To cock the rifle you have to pull down the spring loaded catch at the end of the cocking arm at the front of the fore stock,
|Sturdy spring loaded catch holding the underlever arm flush to the fore stock.|
this allows the cocking arm to drop a little so you can pull it back 120 degrees until it cocks.
|Underlever arm at full cock magically opening the tap loading port, Harry Potter eat your heart out.|
The sweet thing about the MkI and II models is that there is a cam that automatically opens the loading port when the rifle is nearly fully cocked. The loading port can't be closed until the cocking arm is returned and locked in place.
|When this air rifle grows up it wants to be an Air Arms Prosport.|
This is handy in my mind as there is less of a chance of the rifle being dry fired. It's not 100 percent foolproof, but the loading port lever is pretty noticeable and you would have to be pretty well distracted (a polite way of saying idiot!) if you forget to load a pellet before returning it home, where it sits nice and flush in a small cutout in the stock.
|As the loading tap only ever needs to be pushed down it can sit flusher than others.|
It is definitely an adult air rifle as the cocking arm is fairly short and gives the illusion of pulling the piston back as opposed to pushing; the underlever linkage does not connect directly to the piston, but to a a rail that slides along the underside of the piston cylinder.
|All the metal inside the stock is the slide that allows the linkage to push the piston backwards.|
The rail system also triggers the cam for the loading port and pushes the piston on cocking, it is held against the piston cylinder by a plate and a nut.
|The nut and plate that keep the slide against the piston cylinder.|
The plate also holds the cam and the guide holes for the single screw bolt and nut that holds the fore stock side panels in place. When I first saw the bolt side of the stock, I thought someone had bodged it and broke one of the two screws I mistakenly assume were used. No, just one nut and screw bolt running from one side to the other.
The stock itself is made up of three seperate pieces of walnut, the butt and pistol grip and the two side pieces - seeing as the cut out would be for the cocking arm as well as the trigger housing it's just easier to make it in parts.
|Looking very carefully you can see where the pieces of fore stock are joined to the rest of the stock, from just in front of the serial number, out a bit, and sweeping back just past the rear of the trigger guard.|
At first glance it looked like a very clever and professional fix, but again I was wrong. The butt has no shoulder pad and is finished off with a shallow curve with horizontal ridges cut into the wood, the forestock has finger ridges carved down both sides. This is all very common for it's age and looks very shapely, although there a few scuffs and marks which again is not uncommon for a rifle this old.
I took the rifle into the shed and put it over the chronoscope. Using 10 Superdomes at 14.5 grains I was getting a 500fps to 509fps spread, with one odd one at 540fps which I ignored. This converted to 8.3 ft/lb, not to bad for an old air rifle. A couple of drops of oil will soften the leather piston seal and the muzzle velicty should improve, and would do even more so with a new piston seal, main spring and lube.
That's it for now.
All the best, Wing Commander Sir Nigel Tetlington-Smythe.