Idiots guide to classic airgun strips (pt 1)

[Garvin]

https://forum.vintageairgunsgallery....tol/#post-4252



LeonardJ provides these pics:





PS Len made these observations when he stripped a Hy-Score:

"One of the more unusual features, for any spring gun, is the presence of a lubricating wick on the piston head. The next thing that becomes apparent, in spite of being a concentric piston action (barrel runs throught the center of the piston), there is no seal present between the ID of the piston, and the barrel - just a very smooth, close tolerance hole through which the barrel passes - the lubricants form the seal. The piston head is fastened to the skirt of the piston in a manner that allows the head to "float" - no doubt to help maintain a seal. The spring guide also "floats" within the confines of the mainspring ID. The gun uses a common O-ring seal on the piston head, and a proprietary seal within the rear end cap, which seals the main compression tube, so that all the compressed air is directed to the breech, and thus to the pellet."

[Phil Russell]

Gem Style, no maker’s name. Most likely a model 13A from Eisenwerke Gaggenau (Iron Works, Gaggenau)
No. 57748 inside breech with numbers 748 or just 48 on other major parts. This rifle, .177, had been languishing in a cupboard for a long time. No makers name: overall 34” with 17.5” barrel, round but with a top flat. Barrel latch operated by a sprung lever on top of cylinder which, when pressed, allows the barrel to open.
Full of anticipation I tried a test shot; pellet only went about 1” down the, smooth, bore. Time for a service. I removed the screw bolt at the rear of the action near the front of the half stock. This pulls the sides of the cylinder together to nip on the thread of the cylinder / stock plug, holding the stock in place. Removing the bolt allowed the complete stock to unscrew from the cylinder; this gives access to the mainspring. There was a fair amount of preload, maybe 2”. When new I suspect the spring to be 8.25”, 37 coils of 2mm wire 15mm od. The rifle’s spring was about 1” shorter. Remove trigger guard /cocking lever by tapping out the pin at the front of the guard. Guard can now be removed to the rear of the action, bringing the piston with it. My trigger guard pin was bent so a new one was made from a suitable HSS drill shank. The piston rattled its way out of the cylinder. I was surprised to see a huge sealing washer about 9.5mm thick on the end of the piston. There was a steel washer secured by a peened over end to the central rivet rod, 8mm approx. diameter. There was no visible means of removal so I concluded the unit had been ‘rivetted’ into place. As I wanted to get the rifle working, I decided that a new washer would have to be fitted even if this meant sacrificing some of the old central rod/rivet. I decided not to attempt driving the rivet/rod out so removed the peened end to allow the end steel washer and piston seal to be removed. A new leather washer was fitted by tapping the end of the original rivet with a 4mm thread and screwing the new washer unit into place with a delrin spacer to give the same length of piston washer unit as original.
A new leather breech seal was fitted, 10.5mm od x 2.4mm thick with a 3.5mm hole punched in the centre. It is possible that the old seal could have been saved by a good soak in neatsfoot but I decided to do a new one.
The barrel release catch was a bit loose on its mount on top of the cylinder but after a failed attempt to tap out the pivot pin I decided to leave it alone: the pin was very firmly stuck and the catch worked OK as it was. Similarly I did not remove the trigger parts as I saw no need to. All are retained by pins. The trigger can be adjusted by a small screw on the trigger blade that adjusts sear engagement. It was loose so I put a drop of mild Loctite on it. I intended to remove the stock from its steel end plate but only one screw undid so I left it alone.
I lubricated and reassembled the rifle with the original spring and was pleased to see c. 340fps with Geco wadcutters and c. 320fps with AA Field. To satisfy curiosity I removed this original spring and tried a spring of the same specification that was about 1” longer. It made no difference other than being harder to fit. So I put the original one back.
All I all it was great fun despite the piston washer surprising me. I wonder if all gem style rifles are like this?
Cheers, Phil

[Phil Russell]

MILLITA ORIGINAL V
Serial No 105327 with the numbers 5327 marked on virtually all individual parts. Outwardly very good but with two clear faults; the rear sight was missing the adjuster wheel (although the sight element was present) and the barrel release catch was loose which meant the barrel would not stay fully closed. Time to delve a bit deeper.
To strip the rifle it is not necessary to remove the butt from the trigger block but if you wish to do so then remove the two screws holding the steel butt plate in place and then undo the nut visible at the base of the hole. You will need a box spanner, most likely 17mm. I left the butt in place.
Remove the trigger guard, two screws into the action, a wood screw into the butt. There is no need to remove the adjuster screw … my adjuster was missing a lock nut but I found a 2BA one fitted very well so oil blued it and fitted it. The trigger is held by a pin through the end block. My pin was very tight so I left it alone, having ascertained that the trigger functioned as it should. The trigger block unscrews from the action but if you have not removed the trigger, you need to pull the trigger back to clear a cut out in the action in order to allow the block to unscrew. Take care when nearing the end of the thread in case the mainspring is strong. Mine was not, with only about 3cm pre-load. The mainspring lifts out. To remove the piston, release the cocking link by removing the screw at the pivot and lift the link away. It helps to ‘break’ the action. Remove the piston. The piston head was in terrible condition. There had been a leather washer but only half remained and there was a doubled over 4cm flat nail embedded in the remaining half. It was secured by a central screw which I suspect was a replacement as the screwdriver slot was off centre. I could see no evidence of a leather cup shape to the washer, just a disc. I made a new leather disc washer from 6mm leather hide and found a new retaining screw which I fitted with a steel dished washer countersunk into the leather disc. The leather was trimmed to just proud of the piston outer edge and left to soak in neatsfoot oil while I continued the strip.
Remove barrel with action broken by removing the keeper screw on the pivot bolt and then unscrew the pivot. Barrel just lifts away. To remove the barrel catch, drive out the pivot pin, approx. 5.5mm diameter. Mine was very tight and, I suspect, a replacement because the small spring that activates the catch was far too weak to do the job. The catch and spring just lifts out; it will only fit back one way. I found a much stronger spring approx. 12mm long x 5mm od and which fitted in the location holes in the catch and the breech block. A test showed it to work perfectly, restoring a positive barrel fitment.
The breech seal seemed quite OK so was not touched.
Attention turned to the rearsight. I hoped to find a replacement screw that could be modified to form an elevation adjuster but failed. The required thread was clearly very fine and I failed to match it. Purists look away: In the end I made a new adjuster from Delrin and used the thread on the sight base as a die to slowly cut threads in the Delrin. It took a while but was successful.
Rebuild was straightforward. Parts were lubricated as necessary during the rebuild. I started by assembling the barrel catch then refitting the barrel/breech. This is easier with the action in the broken position. Close the action and test tighten the breech pivot bolt to ensure you get a good nip on the breech while still being able to fit the pivot keeper screw. You can adjust this by the use of a shim under the bolt head but this was not needed. Assemble piston (with a little grease on the body ends) in the cylinder making sure the cocking slot aligns with the cylinder slot. Replace spring (lightly greased as required) and refit the trigger block / butt assembly. This is not the easiest job in the world and I clamped the action in a padded vice for stability while I engaged the threads on the trigger block with the action. Take care not to cross threads and remember to pull the trigger to allow the block to seat fully. Replace trigger guard.
Testing with various pellets produced velocities ranging from 486 to 508 with excellent consistency for any particular pellet. This is, I believe, about on spec according to data published by BB Pelletier (Tom Gaylord). Overall, I am quite happy.

Note: Quite by chance I found pictures of this exact rifle on Garvin's VintageAirGun Gallery.

Cheers, Phil

[Phil Russell]

Diana / New Champion 1905 Patent Model.

Also known as the MGR 1905 model. John Atkins has told me that to call it a Diana is not strictly correct as the Diana name was not registered here until 25 April 1907. Outwardly it is very similar to other break barrels of that era with a stock secured to the trigger block by a long through bolt and the trigger block screwing onto the cylinder. There are, however, a few significant differences which will be mentioned as we go through the strip and rebuild procedure. Maybe the most obvious is that the cocking link moves in rails fastened to the top of the cylinder. The LH side of the breech has the word PATENT stamped towards the top. Underneath this is a stamped circle with the letters MG over R. No doubt for Mayer and Grammelspacher of Rastatt, Germany. The lower flat on the octagonal smooth bore barrel near the breech is stamped ‘Manufactured in Germany’. The front 19.5cm of barrel is round. The name Champion / New Champion was apparently given to models imported into the UK, but does not appear on the rifle. Serial number of this model is 2102, stamped on the breech face visible after breaking the action. Research suggests this is a ‘Heavy’ pattern of this rifle; a ‘Light’ pattern, slightly smaller was available.
To strip the action: remove trigger guard, 2 screws/bolts. Remove trigger by knocking through the trigger pivot pin and lifting away the trigger and its spring. The trigger adjuster screw is mounted in the trigger, not through the trigger guard as on similar construction rifles e.g. pre-war Diana 27. Note that this pin is a tapered fit in the trigger block. The trigger spring on this model was very bent so a new one was fitted, using the old one as a pattern. Remove steel butt pad, two screws. Undo the nut inside the hole in the stock; a 17mm box spanner will most likely be necessary due to the depth of the nut in the stock. Note the washer under the nut. Pull the stock off the trigger block. Do not twist the stock to get it to come off the long through bolt as there is a spigot on the trigger block that goes into the stock; twisting the stock at this point will split the stock. With stock removed you can unscrew the long through bolt if you wish but it is not essential.
Unscrew trigger block from the cylinder. There could be reasonable preload so take care. I clamped the cylinder in a padded vice and wore a leather glove to unscrew the block; it was stiff to start. With the block removed, remove the mainspring.
To remove the piston it is necessary to remove the cocking link. I removed both the barrel and the link by removing the two screws. The link needs to be carefully lifted away from the guides on the cylinder after being folded back almost 180 degrees while at the far end of the cylinder slot. The piston can now be slid out of the cylinder. Note that the cylinder is threaded on the outside where it screws onto the trigger block meaning there is no danger of the threads damaging the piston seal when the piston is replaced.
The components were cleaned and the rifle re-assembled with suitable lubrication. This is a direct reversal of the strip procedure: assemble piston and mainspring in the cylinder followed by screwing on the trigger block. Attach barrel and cocking link. Reassemble the stock through bolt, replace stock and secure with the nut; remember the washer under the nut. Reassemble the trigger and spring making sure the spring locates in the trigger recess and the recess in the end of the stock. It is easier to fit the trigger using a suitable drift and then fit the trigger pivot pin once it is all aligned. Refit trigger guard.
A few facts: Rifle length 106cm. Mainspring was 250mm long, 18.7mm od, 2.8mm wire and 38 coils. It was quite straight. Piston 28mm diameter, 140mm long including head, weight 227gm. Cylinder od 32mm, trigger block od 38mm. Barrel octagonal 28.8cm measured from end of breech jaws then round for 19cm to muzzle. The piston seal looked good, being leather about 6mm thick secured by a central screw. Breech seal looked good. After this service rifle put out 8.4gn AA Field at c 610fps for c 6.9 ft lbs. Quite Happy.

Extra: The barrel detent engages with a plate fixed to the end of the cylinder by a 3mm grub screw which passes through a spigot on the plate that goes into the cylinder end. On this rifle the plate was a little loose and the securing grub screw was unable to be tightened or removed due to stripped threads. It was removed and replaced with a new grub screw, resulting in a firmly fixed plate.
Cheers, Phil

[Phil Russell]

THE MIDLAND GUN COMPANY DEMON DELUXE (AND DEMON)

This rifle, serial No. 878, is a .22 Demon Deluxe and would date from the mid 1920s, I think. Overall it is in good condition although close inspection shows that it has had some refurbishment as there are signs of minor pitting to the action and the stock seems to have been re-varnished at some point. The engraving on the action; a feature that distinguishes the Deluxe from the standard Demon is in good condition and extends to all screws. The top of the barrel flat is stamped ‘The Midland Gun Co, Birmingham Made in England. A test fire showed a very smooth action but output was thought to be on the low side. The rifle dieseled badly with every shot including some smoke from the breech area. It was time to investigate further.
If you have ever stripped similar rifles e.g. pre-war Diana 27 then the format of the rifle will present no problems but there are a couple of things to note. I began by removing the barrel and cocking slide as a unit by removing the barrel pivot keeper screw and then the barrel pivot screw. The breech block was a bit loose in the cylinder jaws. It was possible to tighten this up by tightening the pivot screw but the keeper screw would not then fit. A shim washer under the pivot screw solved this … there was one washer there already. It would have been OK if I had just removed this single shim washer but I thought it best to keep a shim there.
The butt plate was next, two screws. Look for the stock retaining nut visible in the hole in the end of the stock. Just loosen it; mine took an 18mm af box spanner. Then back off the trigger adjusting screw a couple of turns and remove the two front trigger guard screws. Note that the rear guard screw passes through the action to screw into a small angular steel plate on top of the stock. Remove the screw and the guard. Now undo the stock retaining nut and remove the stock. I expected to find that the steel rod holding the stock had a hole drilled through it where it screws into the trigger block but mine only had a ‘half a hole’ as if the rod had snapped in half at this point sometime. I could have drilled another hole further back but left it ‘as is’.
Now remove the trigger. Remove pivot screw and remove the screw while holding the trigger blade. When the blade is free from the action, pivot it on the trigger spring and lift clear.
Turn attention to the cylinder. Clamp trigger block in a padded vice and unscrew cylinder. Preload is not excessive at about 35mm but present so take care. When unscrewed, remove spring and piston. It was clear why the action was so smooth … the inside was liberally coated in enough grease to service a London bus. And it looked like standard wheel bearing grease. The piston washer was, as expected, leather and was in excellent condition. There was some light scuffing on the piston rear which was removed. Everything was cleaned of the old grease. The spring looked OK, nice and straight and fitted the piston and guide well so it was not changed. It measured 34 coils, 239mm long, 3.03mm wire, 12.8mmid, 19mmod. I later found a picture of the parts on the Vintage Airgun Forum and the spring shown was a bit different at 38 coils. The Demon here had come to me with a spring marked 'Demon': 38 coils,2.73 wire, 18.6od.
The leaky breech seal was replaced with a new made leather one .. ½” od with a 5/16” inner hole x approx. 2mm thick.
Note that if you only want to access the spring and piston there is no need for a full strip. Simply remove the two front screws from the trigger guard and unscrew the trigger block, trigger and stock as a unit from the cylinder. To access the piston you will need to remove the barrel and cocking link or just the cocking link as well.
Reassembly is the reverse of the above. I used moly CV grease on the spring and piston. A light lubrication of the leather washer followed. I added a slip washer to the base of the piston and clamped the cylinder in a padded vice and offered up the trigger block in order to get them back together. I tried the reverse but found it difficult as the piston rod is a good fit in the spring guide and getting it aligned perfectly against the preload spring pressure was difficult. Somehow, clamping the cylinder made it easier. When doing this make sure the cocking slot in the piston lines up with the slot in the cylinder.
With the trigger block in place, replace trigger. Hold trigger and its spring together and add the end of the spring into the recess in the block. Swivel the trigger and feed it down against spring pressure until you can add a drift through the pivot hole to hold it all in place. Now feed the pivot screw through to replace the drift and secure the trigger. Make sure the trigger moves back and forth against spring pressure. Return the adjuster screw to its original position.
Add barrel and cocking link, ensuring any shims are present on the pivot screw and that it is possible to add the locking screw to lock the pivot.
Make sure that the stock securing rod is positioned correctly to allow the rear trigger guard screw to pass through it. Add the stock and its securing nut but do not tighten fully. Add trigger guard and the rear screw, making sure it passes through to locate in the angular plate on top of the stock. Just nip tight. Add the front guard screws. Tighten the stock securing nut then tighten the rear guard screw.
While doing this service I noted that all parts were stamped with the serial number 878, including the inside of the butt plate.
Add butt plate. Job done.
On testing I found that AAF were a loose fit and seated maybe 3mm into the breech. 5.6mm Marksman and 5.6mm Wasps (new version) seated higher. There was still some dieseling which I have put down to the leather piston washer being impregnated with oil etc. The action was a little noisier which I put down to the amount of grease I scooped out.
Performance came in at around 6 - 6.5 ft lbs excluding higher readings from obvious diesels.
However, the extra noise bothered me so I stripped the rifle again and replaced the mainspring with the 'spare' that had come with the rifle. There was maybe an extra 25mm preload which made fitting the spring more of an effort as the piston rod was a good fit in the spring guide and both had to be perfectly lined up against the preload pressure. But on completion, a test showed the previous noise had gone. Performance was the same but the rifle was much nicer to shoot. I shall leave it alone now.
Maybe these figures are still influenced by dieseling but I am happy. And now quite fond of the old girl.
Cheers, Phil

[ggggr]

I've copied this from what I put up elsewhere in reply to a Senior not cocking, but the basic idea works with all the Webley over lever pistols.

"Ok. Here is what to do.
You have removed the mainspring? Put the guide back in and leave the barrel and linkage off the gun. Slide the piston back with a screwdriver or similar. Hopeully the piston should engage.
If it doesnt, then remove the guide and slide the piston a bit further back and see if it engages. If it now engages, check to see if you have the right piston in it. A Senior one should have a bronze ring as a seal. Mk 1's have a leather seal and Premiers and later guns usually have a Ptfe seal. All the pistons will go in but they will not work.
IF a new sear has been fitted at some point they sometimes need bit of the holding face grinding away to allow the piston to engage.

Assuming that the piston engages while you have the guide in, then try to push it forward a bit against the sear and the sear should hold.

If the sear does not hold the piston then either your sear is worn or the holding ring face on the piston-- Or both.

If with the guide in the piston does engage then that would suggest worn linkages/ cocking shoe, or the fulcrum on the cylinder being worn.

Usually bent pins are not the cause of a gun not cocking, but rather a symptom of people using excessive force to try to get the gun to cock.

More often that not, the problems start with a worn cocking shoe."

[ggggr]

This is a very basic strip of a pre war Diana model 19. There are some versions with safety catches and some badged as Ansonia.
The came to me for checking out and repair and was hammered with Car type Moly grease.
When it came here, the barrel and cocking arm were already off ( for easy packaging), but it is just one bolt to undo on the barrel pivot and the cocking arm has a rivet through it. The cocking arm slides in a housing on the cylinder.
I didnt even remove the barrel catch on this , which is a thumb catch on the LHS, as the pin was peened over and the catch looked good.

On this version, there is a bolt through the trigger housing and trigger guard. Once you undo that and the trigger guard to stock screw , you can either unscrew the trigger housing, pulling the trigger, or remove the trigger first. The trigger pivots on a pin through the housing and has a spring on a pip at the back , and sits in the stock. Im not sure if it should locate on a pin in the stock or have a guide pin, but it functions as it is.

As you unscrew the trigger block , keeping tension on it, it should come out and you should be able to get to the mainspring and piston. The guide is a part or the block.
I didnt try undoing the stock bolt on this gun as the stock had split and been repaired at some time.

The mainspring on this one is probably original as it was a fairly thin flat section one.
The piston washer on this was just a flap of leather, so I had to make a cup washer for it.
The piston washer is held on by a small screw (4mm).

Clean and lube your bits and go to part 2


Ps --link to pics on Dannys site. https://forum.vintageairgunsgallery....ble-prototype/