Spring Gun Tuning

[deadeye dick]

Isopropyl alcohol is generally available from pharmacies. It is also volatile (no smoking!) and will evaporate pretty quickly if you leave the lid off.

No you cant it is not available to the general public, my wife gets it because she lectures and teaches nails and beauty but I have tried to get some without success I believe you can buy it in the USA over the counter

[neralcm]

Just bought a litre of the stuff from an electronics store, about £11 also available in a spray can (can't spell aerosol). Ideal for degreasing as it leaves no residue. Used it on my 97 to fit a V-Mach stage 1 kit, struggled a bit with heavy deposits but did the job.

Stuart

[joekid]

if you,ve got an HW 97/77,thats dieseling this is the way to stop it,get your steel shim make sure you cut it 5mm longer than it needs to be,so you can cut little v,s out of it like a crown, then it will when these v,s are bent inwards form a hole enough for the piston cocking rod ,to pass through, then should form a lip for the spring to keep in place until a few shots seats it into its housing, this shim /stops any unwanted moly getting back into the compression tube on firing, and keeps it where it should be,use this info as part of your tune,as just changing the factory lubes in the HW range of guns makes a big difference, even a simple wipe off the old/ wipe on the new,,molybdenum grease/lithium grease from a car auto spare shop very cheap////and good silicone oil (bisley) for poly seals(plastic type seals)knock your self out!!!

[_cy_]

thanks for the IPA tip... yes it's sold over the counter in USA for cheap.

[Gungeek]

... and good silicone oil (bisley) for poly seals(plastic type seals) ...

No, absolutely not! Anybody who is using oil and especially silicon oil in the compression chambers of spring guns has been badly informed. Regards ... Geek

[Mike95]

I do not pretend to be an expert, but the more rifles I strip and the more I read (particularly Cardew, the Airgun from Trigger to Target), the more I realise just how important it is to size the piston seal to the cylinder. The fit between seal and cylinder seems to be the major factor with older guns, in establishing the ME. I recently stripped and cleaned/relubed an old Meteor with an "O" ring seal and it did not occur to me to try and size the "O" ring. The "O" ring was in good condition and I gave it a smear of molypaste before reassembling. The gun is fireing fine but is low on power. The spring is fine and the relube is fine, therefore must be the seal! I cannot see a nitrile/butyl "O" ring sizing down very much and Ged Finn on another thread suggested possibly fitting a smaller diameter "O" ring. Presumably an "O" ring could be sanded down. The Cardew book demonstrates just how critical the sliding fit between seal and cylinder is, but unfortunately this is just guess work without equipment to measure the sliding fit. Too tight and you have limited power...too slack and you have the same result. The joys of springer tuning!

Mike95

[electric sheep]

Lower ME guns work better with parachute or semi parachute seals with sliding fit but FAC and higher ME springer's work more efficiently with higher swept volume solid seals with a tighter fit. Both need a good moly paste and a cross hatched compression wall to wet edge the seal to wall contact. It is not unusual to have a 30% range of power with the same spring set and different seals.

[rehmk5]

Pardon the slight change of subject from strictly tuning, but I can't start a new thread.

Got a HW80/Beeman R1 question if you would:

Anyone have a 12 ft/lb HW80?

I have a FAC R1 (am here in Calif, USA) that does 7.9 gr Crosman Premier Lites about 1,010 fps.

Problem is, that though it groups accurately, it is hold sensitive in that if I switch from shooting standing with a rest, to sitting with a rest (artillery hold used both), the nice and tight groups move vertically.

At about 35 yds, my sitting with rest groups hit about 1.5 inches higher than my standing w/rest groups.

Can anyone comment on how a 12 ft/lb HW80 is about allowing different holds without the groups moving up/down?

Power is nice, but accuracy is better.

I'd get a 12 ft/lb kit for my Beeman R1 if that would make it more like my AA TX200 (which hits the mark, no matter how I hold it. Dittos for my Beeman R7 and HW55s).

Oddly enough, my Beeman R9 is more tolerant of varying the way I hold it and does not shift the groups like my R1.

Thanks, and good luck on keeping your airgun freedoms. Here in the USA we have the "Democratic" Party that would strip us of our firearms, airguns, water pistols, sharpened pencils, etc if they got the chance.

Robert Hamilton
California, USA

[Paul Hudson]

Hi Robert

I found that dropping the power of a 12fpe HW80 down to 10.5fpe and using 7.9g pellets (Mosquitoes) made a huge difference. The rifle was much more tolerant of different holds, simply because it exhibited MUCH less recoil.

Also, putting the action into a heavier stock further reduced recoil. It's the only 80 I've shot that let me keep the crosshairs on the target throughout the firing cycle.

I've since sold the rifle to Adam77K on here, so it might be worth having a word with him...

Paul.

[darren m]

how can you add some weight to your rifle stock with out ruining it .

[rehmk5]

Hi Paul,

Thanks much for your reply. Non-hold sensitive R1 at 10.5 ft/lbs M.E.? Very interesting. And with the factory weight (heavy) piston at that! Imagine!

I had a custom, lightweight piston made for my .177 FWB124 springer (factory piston: 10.5 oz & custom 124 piston: 8.5 oz), and put in a soft tune kit that had 7.9 gr JSB Exact Express 4.52 doing 770 fps (7.9 gr CPLites did 730 fps with same tune due to tighter fit). Hold sensitivity was reduced, but still had about 1" vertical difference between where the groups hit at 40 yds, sitting w/rest vs. standint w/rest.

Do you remember how the R1/hw80 was at 12 ft/lbs ME? I'm not sure I have anything to drop my R1 down to 10.5 ft/lbs, but I do have an old Jim Maccari 13 ft/lb kit I might be able to use to get down to an even 12 or 11 via no spacing.

Again, thanks for your comments.

Robert Hamilton

[Paul Hudson]

Hi Robert.

At a shade under 12fpe it was tooth-jarring

I dropped the power simply by shortening the spring slightly. I also sized the seal for a sliding fit - that is, the piston and seal would slide gently down the cylinder under its own weight, stopping if the transfer port was blocked.

Darren - I fitted it in a Sono Kembang GinB stock which added nicely to the weight.

However, one of my 97Ks sat in a brute of a walnut stock that I added around 5lbs of lead to - and you couldn't tell unless you tried to lift it . The simplest way was to fill a few lengths of 15mm copper water pipe with lead, drill a series of 15mm holes into the end of the stock under the butt pad, then slide the weighted pipes into place.

Paul.

[rojin]

Hi Robert

I found that dropping the power of a 12fpe HW80 down to 10.5fpe and using 7.9g pellets (Mosquitoes) made a huge difference. The rifle was much more tolerant of different holds, simply because it exhibited MUCH less recoil.

Also, putting the action into a heavier stock further reduced recoil. It's the only 80 I've shot that let me keep the crosshairs on the target throughout the firing cycle.

I've since sold the rifle to Adam77K on here, so it might be worth having a word with him...

Paul.

Totally,10.5 flbs in a medium to heavy springer is perfect imo. I have a prosport .177 running at 10.8flbs. I made the spring myself from a oteva grade material,bliss to shoot.

[fish4london]

Glad i just read this thread . Just got myself the vmach kit to fit an old Hw 77 and had completely overlooked de-greaser. So many thanks.

[lost?]

great thread, will assist my airsporter rebuild greatly