Spring Gun Tuning

[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.

[Hsing-ee]

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.

I think that is too much lube; Cardew's experiments were fine on the leather-washer out-of-true-cylinder guns of the time, but modern rifles work well in the pop-gun phase and do not NEED the boost from 'fuel'. If you over-lube with a drop of SM50 every 1500 shots you will get diesel shots and inconsistency generally, weakening the spring and losing accuracy. The combustion theory is a controversial one, even during Cardews heyday - in 1981 there was an experiment with a DRY lubricated FWB Sport which made a healthy 11 ft lbs. Note this rifle had a plastic parachute seal and the legendary FWB cylinder which is made to extremely close tolerances.

[sniper24687066]

I might just give this a go,many thanks for all the info.