Osprey rebuild/tune-up, any tips?

[evert]

Theras an old Osprey in my Collection of vintage British springers, in need of some service

Its missing the loading tap, and was sprung with a square section spring that seems to have ovaled the sear pin holes and the holes in the cocking arm. Not very bad, so the gun will be made into a shooter.. Then I can leave the other, close to mint Osprey untouched

I have previously had very good results with Jim Maccaris HW50/99 spring in the Tracker, so I'm probably covered there, unless someone has a good tip on alternative springs?

Are there anyone here who have experience with seals- what should I use? Replace the piston rings with o-rings, as I see some of you have done, or machine the piston for a HW30 seal?

And then theres the tap, and tap fitting... I see there are conical and cylindrical taps, so I'll have to measure it and see what I have. When fitting taps, is it best to lap them in with abrasive compound, or to fit them with emery paper("only the bright spots") or are there other ways?

Anyone have any tips on where I can get a new loading tap?

Loads of questions, I'll be grateful for constructive and informative answers

[mallyally]

John Knibbs have the loading tap in stock @ £30

[evert]

Thanks, that might be the way to go if I find it to be a conical one, I'm still not home with my tools.

Does anyone have any experience in fitting these taps?

[torrens]

Hi evert,
I machined the piston down on one of my Ospreys and fitted a HW30 seal. The problem was the end of the cylinder must have had some machining marks or scratches. It shot well at first but eventually power dropped as the seal got damaged. My solution was fit a good old fashioned leather washer and it shoots very nicely.
The other one was rebuilt with new Webley synthetic rings, shot great for two years, noticeably quiet and accurate. Eventually these wore and the rifle got mechanically noisy, still accurate. My solution was keep one original ring in the rear slot and an "o" ring on the front; better but not as quiet as the proper set- up.
If the "o" ring eventually wears out I'll probably retro- fit another leather washer, it's now got a Beeman peep sight instead of a 'scope so just for fun target plinking at 20 or 30 metres.

Good luck with your rebuild
torrens

[evert]

Thanks! I dont have any synthetic piston rings, only the original bronze ring.

Will try to machine a delrin bearing ring for the rear groove, and find a o-ring that fits in the front grove, it sounds like a very good way to go, without permanent modifications!

[evert]

Took the parallell tap out of my problem-tracker(there are a few trackers in the Family too), and it fit quite good.
Running a tracker piston with a fit and sized 25mm diana-seal, the gun is running at 8.5fpe with Maccaris HW50/99 spring.

I have some observations:
-the "ledge" that the pellt skirt seals against in these taps, is a bit further down than necessary-probably crates more lost volume in compression than what is good.
-the transfer port looks a bit on the large side- has anyone ever measured the Osprey and tracker ports?

[evert]

-the transfer port looks a bit on the large side- has anyone ever measured the Osprey and tracker ports?

Had a look inside one of my trackers, that is in bits at the moment, and it seems the transferport in the tracker is smaller. That sounds reasonable, the Osprey seems to be more slammy with the same spring setup.

If i get the time, I'll make up some gauges and have a go at measuring the tracker and osprey ports in the near future.

[evert]

Finally got around to measure the transfer ports on both the Osprey and the Tracker..
Turned a tapered plug ot of soft aluminium, that I could fit on the end on an extension shaft, then inserted it in the port, from the cylinder end, and gave it a few blows With a hammer. That made marks in the aluminium, and I could measure the marked Places on the tapered plug. Took great care to get good measurements, but its probably only accurate to the closest tenth of a mm.

Tracker port: 2.6mm
Osprey port: 4.1mm

That explains a lot of the noise and slam from the osprey, and means I have some sleeving to do....

[flatrajectory]

Finally got around to measure the transfer ports on both the Osprey and the Tracker..
Turned a tapered plug ot of soft aluminium, that I could fit on the end on an extension shaft, then inserted it in the port, from the cylinder end, and gave it a few blows With a hammer. That made marks in the aluminium, and I could measure the marked Places on the tapered plug. Took great care to get good measurements, but its probably only accurate to the closest tenth of a mm.

Tracker port: 2.6mm
Osprey port: 4.1mm

That explains a lot of the noise and slam from the osprey, and means I have some sleeving to do....

Absolutely, 4.1mm is way to large. I would go for 2.8 - 3mm max in an Osprey.

Pete.

[T 20]

Tracker port: 2.6mm
Osprey port: 4.1mm

Hi Evert

This may be of use to you :-

http://www.airgunbbs.com/showthread....ht=Webley+hawk


As the hawk is the same bore and stroke as the Osprey the information could help you, I found a 2.5mm transfer port to work well on the Hawk.

What length is the transfer port on the Osprey as that needs taking into account when sleeving down ?



All the best Mick

[evert]

As the hawk is the same bore and stroke as the Osprey the information could help you, I found a 2.5mm transfer port to work well on the Hawk.

What length is the transfer port on the Osprey as that needs taking into account when sleeving down ?

All the best Mick

Thanks Mick. The port is about 19mm. Made a brass sleeve, and it seems to be a tight 4mm, not a 4.1mm.
The sleeve is 2.5 mm, and the gun has calmed down, but its still not giving me the wanted velocity- Im getting a max of 510fps with 14.5grs pellets no matter what seals or pistons I use(have three different pisons and have tried several sealing options).

I think the next place to focus might be the tap- its from a tracker that has given me a lot of headache, so I'll need to get a couple new taps and tri fitting one really tight.

[abellringer]

evert hi; I don't seem to have picked it up from your thread but is the loading tap tapered or parallel? the tap to barrel alignment is critical and some of my Ospreys with parallel taps have very thin shim washers to align them. With a tapered tap your chances of getting a correc t fit is probably nil as they are hand fitted to each gun. I have not posted parts abroad but if you need piston rings I do have some for sale [PM] me if you are interested. cheers abellringer

[evert]

evert hi; I don't seem to have picked it up from your thread but is the loading tap tapered or parallel? the tap to barrel alignment is critical and some of my Ospreys with parallel taps have very thin shim washers to align them. With a tapered tap your chances of getting a correc t fit is probably nil as they are hand fitted to each gun. I have not posted parts abroad but if you need piston rings I do have some for sale [PM] me if you are interested. cheers abellringer

Thanks for the offer on piston rings, but I do have a few here.

Might need to check up on tap alignment(mines a parallell one)- How do you control alignment before shimming? remove piston and look through the barrel?

[evert]

Success!

Today I cut more off the front of the piston, and made an adapter for HW-seals. Piston plus eal now has the same length and stroke as the original osprey piston.
I had one of Maccaris 25mm HW-seals, that I had sized a bit too much Down for my HW30's. It swas till tight in the Osprey, so a bit of sizing was necessary. Still not free-falling, I like to let a seal bed in rather than beeing too loose.

Took the TP-sleeve out, reamed it a bit with a taper pin reamer to ensure it has a smooth inside surface, and cut entry tapers to bot ends of the sleeve.

Made up a steel tophat and washer to compensate for loss of piston weight from fitting the HW seal, piston plus tophat and washer weighs 210grams.

I have been using Maccaris HW50s/HW99 spring, but added some more preload now, guided by a delrin rear guide.

The gun now does 550fps with an extreme spred of 7fps over 10 shots, with Defiant vintage .22 pellets- that should be 9.7fpe.

Now its time to see what this gun can do- I'm happy with its performance, it just needs to be shot!

[flatrajectory]

That seems pretty good for an Osprey.......well done.
Pete.