Springer spec. opinion please

[TonyL]

Very interesting indeed, sir, and it'll be even more interesting to find out what specification you end up deciding on. Keep tinkering.

[deejayuu]

OK two more springs 244 mm x 40 lb/inch and 255 x 34 both cocked spring force around 185 lb. No weight give 7.5 +/- fpe so a little lower than first trial.
Still fairly flat across pellets. Slightly lower Bisley 10.2 tho' now.
Edit. Sorry got my thong in a twist. Revised figures above. The 255/244 with weight gave 8.5.
Shedtuner! Thanks for the info. Going to start TP at 2.5 and work up if need be. What does "my PE" mean please? Assumed personal experience but have learned not to assume.

[bighit]

OK two more springs 244 mm x 40 lb/inch and 255 x 34 both cocked spring force around 185 lb. No weight give 8.5 +/- fpe so a little lower than first trial.
Still fairly flat across pellets. Slightly higher Bisley 10.2 tho' now.
Shedtuner! Thanks for the info. Going to start TP at 2.5 and work up if need be. What does "my PE" mean please? Assumed personal experience but have learned not to assume.

pro elite ?

[TopDog]

May I ask for another teeny bit of data please? What is the spring space length (ie distance from front inside face of piston and the end cap - no internals!)?

Oh; spring weight helps too!

Have sent you some drawings to your e-mail address.

atvb
David

[deejayuu]

May I ask for another teeny bit of data please? What is the spring space length (ie distance from front inside face of piston and the end cap - no internals!)?

Oh; spring weight helps too!

Have sent you some drawings to your e-mail address.

atvb
David

Many thanks David. Haven't seen e mail yet. Looking forward to reading/digesting that.
Spring space uncocked 210 mm cocked say 132 mm. Original spring 118 g
Dim but willing. Jules

P.S. Edited errors post 17

[Shed tuner]

pro elite ?

yes

2.5 will still be too tight, guaranteed; you can start with 2.8 if you want to be "careful"

[deejayuu]

yes

2.5 will still be too tight, guaranteed; you can start with 2.8 if you want to be "careful"

Ah good. Not premature emasculation then. Glad I didn't assume.

Thanks again. Itching to get to it now.

[TopDog]

Ah good. Not premature emasculation then. Glad I didn't assume.

Thanks again. Itching to get to it now.

Agree with Jon but being less cautious and believing the sums I would plump for 3.2 right from the off! But 2.8; 3.0 and then 3.2 would be fine for the cautious!

atvb
David

[deejayuu]

Well the thick plotens. Todays plan was just resize/restore piston seal, general clean up and fiddle.
Removed barrel to get a better look and as suspected the TP is inserted. Seems to be stepped dia. say 3.8 mm inside, 5 mm outside, with insert near 2 mm bore.
Very reminiscent of Baikal which has synthetic insert to size the port.
Cold as a witch's mammary gland in the shed so will try to remove the insert intact tomorrow then make/fit replacement.

[TonyL]

I wonder if, following the application of some heat to loosen any adhesive, the insert could be easily knocked out to be then sized? Or whether to just ream in situ?

[Shed tuner]

I wonder if, following the application of some heat to loosen any adhesive, the insert could be easily knocked out to be then sized? Or whether to just ream in situ?

you want a parallel TP to remove lost volume, so I'd bore / knock it clean out.

Such a weird design - looks almost like it shoudl have a breech seal in there ?!

[Shed tuner]

say the TP is 2.5x15
I'd defo open to 3mm or it just won't flow.

Normally Id say 3.2 (my PE is 3.2 x 15'and the accelerometer tests show it still being slightly too tight) but the 3.0 will cushion it a bit with the shorter barrel - although being .177 it will maintain higher pressure anyways.

Agree with Jon but being less cautious and believing the sums I would plump for 3.2 right from the off! But 2.8; 3.0 and then 3.2 would be fine for the cautious!

atvb
David

HNY David.
yes, agreed, I didn't have enough data to be 100% confident on someone else's gun, and your maths/models are better than mine

[TonyL]

you want a parallel TP to remove lost volume, so I'd bore / knock it clean out.

Such a weird design - looks almost like it shoudl have a breech seal in there ?!

Yep, know what you mean re the breech seal issue. Having never seen one of these later ones "in the flesh" it'd be hard to say. And, I think some of the later Gamo / BSA designs with the synthetic cylinder end / breech jaws / sleeved barrel arrangement do indeed have the seal at the TP rather than at the breech itself. However, taking a wild guess, this one's maybe just an odd design and that the seal is on the barrel?

[deejayuu]

Hello again. Quick input. Breech seal is on barrel. Failed to remove it so drilled TP to 3 mm and as below. Not scientific strings just a few of each 'cos it's perishing in there.


245 x 34 lb/inch PL 40 Hobby 7gn 6 fpe , SD 8.3 gn 6+, Exact 8.5 gn 7+, Bisley 10.2 gn 6
268 x 36 lb/inch PL 67 Hobby 7 gn 10.8 fpe , SD 8.3 gn 10.3, Exact 8.5 gn 10.8, Bisley 10.2 gn 9.8
255 x 34 b/inch PL 50 Hobby 7 gn 7.6 fpe , SD 8.3 gn 7.8, Exact 8.5 gn 8.6, Bisley 10.2 gn 7

Next step is recheck this data then take TP to 3.2 mm as advised. Never doubted the modelling route provided by them that know just enjoyable, for me, to follow a fairly well trodden path and see where we go.

Relishing the prospect of reading comprehensive tutorial support, freely shared with us, which will take some time to digest and compare with our practice.
Many thanks again. Luv it!

[TonyL]

Nice work.

If you can get your hands on any, it would be nice to also test the power with the lighter Exacts - RS and Express. May nudge it slightly over the energy obtained with the Hobby.

How does it feel at the higher preload value in terms of cocking effort and perceived recoil?