Spring Gun Tuning

[6519bushman]

If you are able to strip the gun, clean the piston and chaimber with hot soapy water (hotter the better) so there is no more grease or oil. Pay very close attention to the piston seal removing it carefully and again cleaning it with hot soapy water. Once you have done this clean the parts once more with pure alcohol as a final precaution against grease and oil. At this point you can check the cylinder for scoring, if its bad you may wish to have it polished. Assemble the piston into the cylinder using a silicon based lubricant on the piston seal (use very sparingly the lightest of wipes with finger, almost undetectable) The next step is possibly a little more difficult. Take a look at the spring....... wipe with a rag removing all the grease and oil (not to the same standard as the other parts mentioned. Then look at the spring guide. If its plastic and loose fitting, have one made out of silver steel so that it fits with no play! (make sure you accomodate the spring guide in the piston as this runs through the other guide and engages the trigger sear, HW80 that is) into the spring. This is one of the secrets to Dampening twang. There may be after market parts you can source for this. There used to be a kit out there with an ox square sectioned spring and a solid steel guide. Also supplied was a replacement piston seal and lubricants. I doubt if this is available as it would come under the new VCR act. However it is a very simple job for a competant enginear to make one for you. Just dont! fit a bigger spring! This tight tollerance piston guide along with a carefull application of moly grease from a car parts dealer dampens and smooths out the operation of the piston. DO NOT GO MAD WITH THE GREASE as it will make its way into the piston chamber when you cock the gun, and mess up what you have tried to attchieve, and will make you gun exceed 12lb muzzel energy. The next step is to clean you barrel with a copper brush then a nylon brush. Once you have run these brushes through the bore several times use a solvent to remove the lead build up and repeat until there are no marks on a cloth pulled through the bore. I the use Alcohol to finally remove any trace of oil. Job done. Reasemble the gun. And run it in with a tin of pellets, then recheck it with a chrono. Any sign of ignition or a burning smell, you have either not cleaned all the parts adiquately or have used accessive grease on the spring.

Good luck if you get it right you should have a accurate quiet consistant gun that should not need servicing again for thousands of rounds.

[Andy001]

Can of Dri-Slide or tube Molykote GN paste
Abbey LT2 molybdenum grease
Abbey SM50 oil
Abbey Silicone oil


Can anyone tell me where can i purchase these from? JSR, havent got their website back up so. I've a few of my rifles to do in a few weeks time.

Can anyone tell me, does the process of lubing the piston and inner chamber of the rifle defer between a alloy piston head and a synethic (spelling sorry)

Thank you.
Andrew.

[jimcam]

I've read this through as its very informative I'm going to try this out on an old SMK i've got lying around the shed somewhere.

[DOIDY1]

Hi all can you help .I have a 75 original recoilless 6 mtr mach .is it possible to increase the power with a deferent spring so could use it for field target

[Hsing-ee]

Hi all can you help .I have a 75 original recoilless 6 mtr mach .is it possible to increase the power with a deferent spring so could use it for field target

The compression chamber is too small, don't bother. FWB300 Match rifles can be boosted a bit, to 7.5 or 8.5 ft/lbs. Sell it and get a Prosport.

[ozzie642]

hi, just put new spring etc in my .177 stingray, seems to be only managing 600 fps, any ideas why this could be, could puttin to much grease on mainspring have any adverse effest as i have put rather alot on it, any help much appreciated

[Hsing-ee]

hi, just put new spring etc in my .177 stingray, seems to be only managing 600 fps, any ideas why this could be, could puttin to much grease on mainspring have any adverse effest as i have put rather alot on it, any help much appreciated

If you read the Tuning Guide at the beginning it says to use a very thin SMEAR of grease. Slathering it on with a trowel will cause problems.

Read the guide, degrease, check the piston seal and breech seal for nicks, relube and try again.

[ozzie642]

k, stripped all down, and degreased, noticed a tiny dent on the piston seal, think i may have done that when refitting it, could that cause such a big drop in power as its a very very small dent, if so can you recommend a supplier and any tips on refitting it into the chamber avoiding any damage, also next time i change mainsprings can you recommend a certain make for quality and power, thanks

[torville]

Saw recently in wellknown . airgun magazine an article for young folk showing a can of "3-in-1" next to an airgun which kinda disappointed me as this oil is ,in my book a def.no-no if it gets in front of piston and even if it builds up in workings of springer-;iBELieve "3-in-1" contains silicone and molecules of this useful substance can nevertheless "clump" into diamondhard granules interacting under metal-to-metal friction and these indeed scarred c/cylinder of an airsporter I had AS a kid in the early seventies also piston washer lost it's zip drastically and in only a short time after I enthusiastically started dosing the entire action via loading-tap (fascinated by smoke).
Does anyone know for certain if there's a lot of silicone in the above as it's my theory that there are far better gun0oils to use with the spring-gun and those that claim rust-inhibiting properties may or may not contain the silicone molecules-;believe that [ballistol] and [jansonite] are two old-fashioned (shot)gun oils which were formulated before the spaceage and both remarkable for the rust-beating quality which has seen them stand the test of time appearing, as they do in sporting stores of today;[bisley] and [parker-hale] are two good oils which are stressed as purely mineral- only, as well as the budget[napier] and the rarely seen [hoppes] (pron.from polish surname "hop-ee") this trad.gun-oil of the U.S.A. known to be one of the oldtime rust-inhibitors without silicone involved and all extremely hot if they find their way in front of piston in more than the smallest amount tho' a tiny drop does no harm I reckon indeed the first airgun designers were delighted by the diesel phase at the core of the original concept sp-ring-gun circa eighteen sixty-six*regards .torville
*Havilland & Gunn/[quackenbush] nr.1&1/2

[torville]

Back in the eighties Cardew recommended popping [hw] spring-guide into piston as a simple way to add weight and a home-turned tophat at the breech end with thrust bearings on both parts to ease spring torque dynamics.regaRDS torville.

[Snooper601]

Back in the eighties Cardew recommended popping [hw] spring-guide into piston as a simple way to add weight and a home-turned tophat at the breech end with thrust bearings on both parts to ease spring torque dynamics.regaRDS torville.

It's the other way round!

Top hat shaped guide in the piston, short and light.
Long spring guide at the rear end, breech, ideally fixed to the trigger block to save damage to the rear block by rotational forces. Non moving part so weight is unimportant, meaning it can be long enough to almost touch the top hat when the spring is fully compressed.

Cheers

John

[leon1935]

I have a 1919 BSA Standard .22

Would the tuning guide apply to a gun of this age.

It is surprisingly accurate to about 30ish yards, further than that it is me...and Iron sights..

Leon

[Hsing-ee]

I have a 1919 BSA Standard .22

Would the tuning guide apply to a gun of this age.

It is surprisingly accurate to about 30ish yards, further than that it is me...and Iron sights..

Leon

Ideal for a BSA like that, although the parts should need very little polishing after all that use! You might need to buy or make a new piston washer from leather, or you could possibly get an adaptor for a plastic parachute washer. Have fun.

[torville]

This is a term coined by the late ,great gerald cardew,airgun boffin of the seventies and particularly interested in the [v-rok] mod.35 export with it's leather wasjer-;card reckoned that the piston washer,reciprocating back and forth is intended to scrape some lube i.e.whatever petro-chemical oil/grease is present in the action and either prepped on n/cylinder walls or emerging from "fuel store" on spring which he recommended as three teaspoonfuls two-thirds up mainspring ,"fuelglobule" nestling inside piston and a piston sleeve/grease shield to prevent too much flying off thru cocking slot onto walls of n/cylinder and from there scraped forward in front of piston with each shot and this scraped fuel righteously detonating in the diesel phase .
our experiments with the [v-rok] mod.80 show that with no lube there is only a popgun phase;with too much finding it's way in front of piston result erratic vel. and interestingly some diesel giving high reading but most excessive detonation/diesel remarkably hampering downrange performance with low vel.resulting.
our verdict that with modern [v-rok] piston without open cocking slot where grease can get flung thru there can be no call whatever for piston sleeve of thin stainless which would be superfluous but certainly have heard of ptfe/synthetic sleeve which might well reduce mechanical noise but any grease shield function redundant due to all grease being confined inside piston of modern [v-rok] pattern .
ideal fuelling we reckon is one drop of ramsbottom[sm50]via t/port ( allow cocked gun to stand a few hours) every three tins pell )note: first shots after fuelling use two heavy pell each time for a coupla loads until any excessive smoking dies away)and on rebuild smear of [abbey LT2] on area where piston washer meets piston so it remains in this slight groove also [moly paste] on skirt of piston and some on upper rear of n/cylinder cos piston gats pushed upwards as wellas backward on cocking and thus bears on this upper surface of n/cyl at rear action plus of cours an amount of grease on mainspring to lube coils but not so much to reduce efficiency in effort to dampen mechanical noise.regards.

[Paulsmith]

Thanks to Hsing-ee for the following :-


Tuning The Older Springer

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ALL WORK DONE USING THIS INFORMATION IS AT YOUR OWN RISK - APPLY COMMONSENSE TO YOUR WORK AND SEEK ASSISTANCE FROM A QUALIFIED GUNSMITH IF YOU GET OUT OF YOUR DEPTH. Use a spring compressor and be careful!

If you want your old or new-to-you old spring-piston rifle to give you its best then you could try the following tune-up. It takes a bit of patience and elbow-grease and dosen't involve any drastic modifications but if you follow it carefully your rifle should shoot sweetly afterwards for a good long time.

The following is a basic tune for spring-piston rifles which was common in the late 1970s and early 1980s. The idea is to make the rifle as smooth and consistent as possible, and does not involve modifying the rifle in terms of piston weights, top hats, etc, that is for the more advanced airgunsmith. I used this on a Feinwerkbau Sport recently and it would cut 7mm groups at 25 yards from a rest, and in my 30 year old BSA Meteor which does 10ft/lbs and 20mm groups with a standard spring so it seems to work OK. The guide refers to a rifle with a leather washer, obviously don't soak the washer in silicone oil if it is of a synthetic material, just wipe a small drop of SM50 over it before assembly.

For the full works you will need:

new spring
new piston washer and buffers if fitted
new breech washer

Can of Dri-Slide (or Gun Slide from Chambers) or tube Molykote GN paste
Abbey LT2 molybdenum grease (J.S.Ramsbottoms has this)
Abbey SM50 oil (J.S.Ramsbottoms has this)

Solvol Autosol metal polish ( a car accessories shop like Halfords or a hardware store)
Methylated spirit or white spirit
Very fine abrasive paper
Cheap toothbrush (unused)
18” length of broomhandle
Couple of packets unused ‘J’ cloths or similar

The idea of the tune is to make sure the bearing surfaces are smooth and appropriately lubricated, with the aim of consistent mechanical action giving consistent velocities without dieselling and so giving good accuracy. The molybdenum in the Dri-Slide binds to steel giving a very slippery hard surface.

IT IS ABSOLUTELY ESSENTIAL THAT YOU CLEAN ALL THE PARTS COMPLETELY AFTER POLISHING THEM WITH ABRASIVE PAPER OR METAL POLISH. Use newspaper under the parts as you work and throw them out as they are soiled. Have a clean area to put your clean parts and don’t do ‘dirty’ work next to them. Be careful with naked flames and the hair-drier, the methylated spirit and the carrier element in the Dri-Slide ar e both highly inflammable. WORK IN A WELL VENTILATED ROOM OR WORKSHOP.

1. Place the new piston washer in a pellet tin or similar receptacle and pour over Abbey SM50 to cover it completely. Leave to soak overnight.

2. Disassemble the rifle, taking care to store small parts so they don’t get lost.

3. THE COMPRESSION CHAMBER

A. Degrease all the parts and the inside of the compression chamber using the meths. The broomhandle should have a 3” slot cut in one end so that a stip of J cloth can be slid in and wrapped round to give a cleaning head. Be very thorough, and keep using fresh strips of J-cloth until they start coming out completely clean. Check that the transfer port is clear by using a non-metalisc implement like a cocktail stick and examine carefully by eye. Use the toothbrush and methys to clean the threads that the rear cylinder block screws into. Dry the inside of the compression chamber using further J-cloth strips.

B. If you feel it necessary you can remove the sharp edges on the inside and outside of the cocking-slot. Pack the compression chamber with cloth and using a spatula or table-knife with the fine abrasive paper wrapped around it smooth the inner and out edges of the slot. Don’t overdo this, just remove the sharp EDGES from the slot. Degrease again and be meticulous about removing all the metal filings and abrasive dust using methys and J-cloths. Remove the packing cloth and degrease again until you are sure all the dust has been removed.

C. Using a hair-drier, warm the compression tube by blowing hot air inside and outside the tube body. When it is warm, pour a tablespoon-size amount of Dri-Slide into the compression chamber and roll the chamber around so that the liquid coats all of the surface of the chamber and also further back in the area above the cocking slot. Be careful not to lose all the Drislide out of the transfer port! The chamber can be left to dry for a couple of hours or overnight. Alternatively, rub in some Molykote GN paste onto the whole surface of the inside of the compression chamber.

D. When you are ABSOLUTELY SURE IT IS DRY, use a tightly-wound long piece of J-cloth on the broom handle, burnish the surface of the compression chamber thoroughly. A lot of the Dri-Slide will appear to come off, but it is leaving behind a layer so don't worry.

4. THE PISTON

After disassembling the piston, degrease it inside and out as above, using meths and J cloths. Polish any scratches on the piston body out using the fine abrasive paper, using a rotary action i.e. turning the piston on its axis and holding the paper still so the mark is polished out in a ring around the piston. Polish the whole of the outside of the piston with Solvol Autosol, particularly the back of the piston where it makes metal-to-metal contact with the cylinder wall. Use a J-cloth and to apply and polish off the Solvol. Carefully polish the surface of the bent (part of the piston which engages the sear) with Solvol on a J-cloth drawn tight over something flat and rigid (e.g. a small file). Degrease and clean with meths. Heat the piston up with the hair-drier and coat the inside AND the outside of the piston with Dri-Slide as with the compression chamber, except you don’t need to polish it in afterwards, just leave the coating as it is.

5. THE SPRING

Take a peice of the fine abrasive paper and place it on a very flat surface e.g. a suitably strong piece of glass or steel plate. Polish polish the flat ends on the paper until they are shiny. You can make this a mirror finish if you then polish the ends using Solvol Autosol on cloth stretched over the plate. Degrease and clean the spring carefully afterwards.

6. THE PISTON GUIDE

Degrease inside and out and polish out scratches using a rotary action using the fine abrasive paper and then Solvol Autosol to give a shiney surface. If you like, pad a vice and use a file to remove the sharp edges on the base of the guide. Degrease and clean as above. Make sure you clean the passage through the middle of the guide and get rid of any old grease and dust in there.


ASSEMBLY

1. Take the piston washer that has been soaking in SM50 and squeeze it dry using a J-cloth. Fit it to the piston, avoid getting any lubricant on the screw/bolt attaching it to the piston body. Smear a couple of drops of SM50 around the base of the leather washer (away from its face).

2. Take a lollipop stick and smear a stripe of LT2 grease about 1” in width around the back of the piston (trigger end), be fairly generous.

3. Fit the piston back into the compression chamber, easing the piston head into the chamber gently. It may be a little bit swollen at this point, but persist in easing it in and don’t use hammering or excessive force. Line up the cocking slot in the piston with the one in the compression chamber.

4. Using a small pad of J-cloth, apply a thin smear of LT2 grease to the outside of the spring and a generous layer to one flat end. Fit the spring into the piston with the greased end forwards.

5. Apply a liberal amount of LT2 grease to the outside and INSIDE of the spring guide and fit it to the end of the spring.

6. Smear a little LT2 grease on the threads of the back-block and use this to compress the spring and reassemble.

7. Reassemble the rest of the rifle using LT2 grease on all the main points of wear. Apply SM50 oil to the trigger by dropping it into the mechanism, allow the excess to drip out before reassembly. Replace the breech washer with a new one, and clean the barrel in the normal way. Make sure all the stock screws are tightened appropriately (not too loose, not too tight).


The rifle may be a little bit smokey the first ten or twenty shots but should then settle down to be very consistent. All that is needed in terms of lubrication after this is a drop of two of SM50 at the joints occassionally, and once every 1500 pellets or so a drop of SM50 ***BEHIND*** the piston washer, which can be done by removing the stock and putting the oil in through the cocking slot. Leather washers can take a long time to bed in, so I recommend doing alot of plinking, like two or three tins of pellets, before the gun reaches its peak. Then you should be able to shoot the rifle for thousands of pellets without doing anything more than slip a new spring in occasionally and a sparing use of SM50.

CAUTION: Do NOT over-lubricate. Stick to the amounts indicated here - less is more, especially with polished bearing surfaces.

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Looks like sound advice there, thank you.