View Full Version : Stripping a Bugelspanner: my experience

Phil Russell
15-10-2008, 07:07 PM
I have just completed a strip of an 'Original' Bugelspanner in 0.25.
I had a guide document from AGW Dec 1979, kindly supplied by another forum member (John, thanks) but there were a few differences in procedure needed so I thought this may be of interest.
Before I started, our rifle was delivering 20.1 gn pellets at about 235fps. I thought it should be more but did not expect miracles due to the relatively small size of the air cylinder.
The AGW article started by stating that although it was possible to easily remove the forend, it was not possible on the demo model as the pivot pin had seized. After a few attempts at removal I realised that so had mine so I decided to leave it alone as I did not want to damage the forend. All other work was thus done with the forend/barrel in place. I did clean out the barrel latch ... simply a case of removing the side plates, unscrewing the pivot pin from the top left of the forend, opposite the latch lever and lifting out the catch and spring.

My spring compression lever butt swivel pin was a simple push fit through the butt, but with a hexagonal head. No securing screw. Simply removed with a drift.
Remove the two rear screws from top plate; on my rifle these thread into the lower (trigger) plate. Leave the central third top screw in place!
The stock can now be gently wiggled rearwards and lifted off. I released the cocking mechanism by removing the screw connecting the cocking rod to the piston rod .. mine undid from the rh side.
With all that out of the way, unscrew the underlever latch spring ... small screw on left hand upper side near the piston rod.
Undo the front screw in the lower, trigger plate and wiggle the plate and trigger unit free. There are no springs to ping around so do not worry but do it carefully.
The next stage is to get to the springs and the piston.
You will need a spring compressor here. I used a sash cramp. I strapped the action to the cramp and used a 'half inch spanner socket' over the protruding piston rod so that the cramp pressure would bear on the action back (face) plate. With all secure, remove the final retaining screw from the front of the top plate. The springs etc are now being held back by the top plate slotting into the face plate on which the springs thrust. Remove it carefully ... mine needed a lot of wiggling, all the time making sure the face plate and action were held firmly by the cramp. With the top plate removed, slowly unwind the cramp ... it will need about 2 inches before the spring pressure is relieved. Remove spanner socket. The face plate, springs and piston are now free.
My springs looked OK... they were numbered 1 and 2. The shorter one was fitted into the compression tube first. I just cleaned and lightly greased them.
The piston looked a bit rough so I stripped it down .. a very thick leather washer made of two leather discs about 4mm thick each. I made new ones.
The inside of the compression tube was filthy with bits of debris ... thorough cleaning and a polish was needed. But it was pretty badly scoured, presumably by the springs, and did have some imperfections in the surface finish .. a few small cavities that I could do nothing about.
Rebuilding was a case of reversing these operations but beware that you will definitely need a spring compressor to rebuild. Assemple the piston with the piston rod trigger sear hole downwards. The face plate needs to have the underlever latch spring screw hole at top left. Slowly screw everything together with the sash cramp or whatever you are using. When all is perfectly aligned, refit the top plate and screw in position.
Other parts went back in reverse order of dismantling with no real problems although fitting the lower, trigger plate, was a bit fiddly and I needed to resort to a small cramp to pull the face plate lower edge firmly to the action in order to get the trigger plate to tap into place (these top and bottom plates are very good fits). The stock needed some wiggling to get right as well.

Was it worth it? Overall, including making new washers and extensive cleaning etc it too me about 5 hours. A lot of this was taken up in improvising ways to get the correct compression distance to deal with the spring removal and refitting. But at least I now know how it all works. And I know the springs are not broken. Individual main parts all had a serial number as well .. 1852. Cocking components looked to be stainless steel (?) while it becme clear that much of the action had, at one time, been chrome or nickel plated.
Performance has not improved much ... an extra 30fps at the moment but I guess it may improve. Maybe if I took just a little more off the piston washer to make it move more freely ...
I do not think there is anything I can do to improve the breach seal ... at present it is just metal surface to metal surface and I cannot believe that it is a perfect seal. I am sure it would only take moments for an engineer to cut a slot for a breach seal to be fitted ... but that would be sacrilege to such a historical rifle and is a strict 'no - no'.
I wonder, however, why it was not done in the first place.

Cheers, Phil

15-10-2008, 10:42 PM
Congratulations on a job well done Phil and thanks for the detailed account. I'll file it away for when I need to take a look inside my Bugelspanner. For the moment it works, so I'll leave well alone until the day that it doesn't. ;)

Phil Russell
16-10-2008, 08:59 AM
Thanks Garvin. Is your rifle a .25? Do you know what fps it produces? I have no reference to go by so do not know if mine is about right or seriously out. I suspect not far off right but it would be nice to know.
My guess is that these rifles were designed for very short range work ....

As a bit of fun I did test mine on the 'garden range' yesterday. Fired horizontally from about 40 yards and from shoulder height the pellet hit the ground at about 30 yards. Adding some elevation I did manage to hit the paper target, but it was like watching a cricket ball being lobbed.

Oh what fun ...
Cheers, Phil:)

16-10-2008, 10:47 AM
Phil my approx. .180 cal rifled Bugelspanner does about 370 fps with a slightly squashed (to stop it dropping down the bore) 8.4 grain pellet. It's probably a .20 cal really but I don't have any .20 pellets. I think you're right and these rifles were designed for short range work. The design only produces low power even when in perfect order so .25 cal is a strange choice of bore size. Maybe it was because they made a satisfying 'thwunk' on knock-downs in a shooting gallery? Maybe gallery owners had to hand out fewer fluffy animal toys using a gun with a banana trajectory? Maybe the public found .25 pellets easier to handle? :D

Phil Russell
16-10-2008, 03:33 PM
Thanks again Garvin. I thought the standard bore was .25 ... but clearly other bores were available. I wonder if .20 was for the American market.

Having been thinking about our rifle (dangerous at my age) I pondered on the metal to metal face contact for the breech and wondered if there was a small gap leaking air. A test on a thin shim (aka a bit of coke tin) showed that the barrel would close with no obvious extra resistance so I duly cut a hole to match the transfer port and tried it. Over a range of shots power went down about 40fps. Quite a surprise. Initially I thought my shim must be blocking part of the transfer port but it was OK. So I abandoned that idea.
Next I tried seating the pellets about 1mm into the bore. Previously I had 'finger pushed' them in, making sure that they were seated below the surface. This time there was a distinct 'nudge' as the pellet seated. FPS went up to almost 300! Wow ... almost a heady 4 ft lbs! This was with H&N field Trophy (20.1 grains I believe) ... cheapest I found at 3.99 for 200.

I may well declare a truce with the rifle now.

Cheers, Phil:)

Cheers, Phil