Bsa .177 Imp Model D service, relube and new spring

[silva]

The bsa .22 supersport I've had on long term loan is going back to its owner as he's recently traded in for a new shooting friendly missis.
So thinking of getting a 43.5 inch Bsa Improved Model D back into tiptop shooting condition as I haven't got a hunting airgun at the moment.

I've got my own idea's, but what modern after market spring, possibly piston washer and relubing regime would you recommend to recommission the rifle, which though in good order with no wear to the mechancs, is dry and definately needs a spring.

Was sort of hoping for about 10.5 flbs whilst still remaining pleasant to shoot. Has anyone had any luck using synthetic piston washers as originality isn't an issue.

Have a spare stock which already has the faint crack around the locating plug, so was going to fit that which takes most of the worry out of shooting these old Bsa's.

Cheers

[edbear2]

Hi Mate.......have been working along the same lines.....

http://www.airgunbbs.com/forums/showthread.php?t=395025

As for guns I have already rebuilt, I have used Knibbs leather washer sets.....polished the piston bearing areas, and when installing washers have skimmed them (mounted on the piston) in a lathe until they are a light sliding fit (dry).......I also assemble the gun with moly grease lightly on the spring and piston, but with a dry washer (soaking it before assembly makes it harder to fit IMHO)....then I fill the loading tap with cengar green oil, and oil the piston washer this way (I normally give it two tap fulls, and leave the gun upright in a corner for 3-4 days)........you will get some dieseling on initial firing, but it soon settles down......It will take at least 2 tins of pellets to really settle down.

Now other people recommend neatsfoot, or even silicon oils, and soaking the washer before assembly...The way I do it is the same as when they were made originally according to John Knibbs, but this does not mean It's the only way (especially with modern lubes) ...spring wise......Johns springs are a bit fierce.....I did a 45 inch model D with these, and it was doing 12.3 pounds .......so I used a set of 43 inch springs from John, and now it is doing about 10.6 and is much nicer to shoot.......you will find that airsporter springs fit, or I have been told that air airs tx200 units work, although with both of these, you may need to reduce the length by a couple of coils.

So..back to your original question......I don't know how the synthetic jobbies will turn out, but will post my findings as soon as I get the cs together !!

[silva]

Cheers Ed,

Thank you for your reply. Glad to see you had an interesting trip to the States and look forward to the results of your synthetic washers.
Just wondering would you go for a single or double spring set up ? As no doubt you have done some R & D on this question !

Regards

[edbear2]

Hi again........on the guns I have, the original twin flat wound springs seem to give the "softest" recoil and smoothest action.....I think T.W. Chambers still have some flat wound repro springs, but you may need to trawl through every prewar BSA they list;

http://www.gunspares.co.uk/shopdispl...=24027&cat=BSA

The double spring set up is supposed to counteract spring torque on firing, but in the old (repro from http://www.cornellpubs.com/index.php)...BSA catalogues and books I have, it seems as if they fitted twin springs to the .177 models and single springs to the .22 "sporting" models originally.......They claimed 600 f.p.s for the long .22 guns at the time, which with adder or BSA pellets comes out at 11.3 -5 pounds energy. I have used airsporter, J.knibbs or Chambers springs in any of mine that I have rebuilt, and with modern round wire springs, there is not much in it between a single or double set up.......I do however, carefully square up, and mirror polish both the ends of, and the outside of the springs......very slowly and carefully to avoid heat build up!......I also polish the trigger block base where the spring end bears on (maybe a place for a delrin bearing here?).......ie. basically any parts where there is contact between metal on cocking or firing. I have not read about or done a huge amount of "tuning", and am basically working on standard engineering principles.......There must be loads of info out there on springers, most of it know by people who have been tinkering for years, and who have built up a database of tricks and ideas......the thing is that if these people do this for a living, they obviously don't want to give all their secrets away!........on my other synthetic thread above I said that I just want the smoothest, consistant action possible, with power at around 10.5 -11 pounds for repeatable performance in HFT type events...So my procedure will be on the C.S...minimise friction and bearing areas (ie. buttons on piston, synthetic seal)....reduce spring torque (polishing, spring guide).....work on trigger/sear/piston notch to try and improve trigger action (you will never get a match trigger on one of these, but a nice crisp 3.5 pounds release should be attainable).....then see what it chrono's at and reduce spring power if power has gone up too much!