Spring fiddling results. Observations/opinions please.

[deejayuu]

As above. Trying to choose a spring to get the HW77 25 mm action in .177 shooting nicely, whatever that means, so
had a fiddle with springs just 'cos they were to hand. All pre-loads with no washers.
Thought I'd ask those that know.
All constructive comment appreciated any others welcome

Length (mm) Pre load (mm) No of coils Rate (lb/in) Velocity (ft/sec)
As found 275 61 33/31 Sq. 42 very fast

240 26 33/31 32 475

230 16 29/27 42 635

From .22 290 76 35/33 26 750

300 86 37/35 Sq. 26 800

Titan xs No 1 280 66 30/28 38 very fast!!

HW 315 101 41/39 20 660

Silver streak 250 36 30/28 35 675 in .177

Thanks for looking
.

[Shed tuner]

the "from .22" spring would be my guess, once you add in a TH, piston sleave and a slip washer, should be perfect.

However the better tests (with the "closer" springs) would be to test with lighter, medium and heavier pelelts (not crazy light /heavy, say 7.3-9 grain range)..

[deejayuu]

Thanks Jon. The pellets are Diabolo 7.3 I have Marksman 8.3 which are slower but consistent.
Will the top hat/slip washer increase the output sufficient to need the spring shortening?
Is "closer" another word for Oops!

Going to try your suggestion and report back.
One of my problems is lack of handling experience to judge good/bad action performance.
This exercise is interesting/helpful, to me, though.

[Shed tuner]

as per pm.. but get yourself to Mick's bash in April, we clearly need to work on that "experience"

[BTDT]

The energy efficiency with all the springs seems very low for a .177" HW77.

Have you checked the piston and breech seals?

[deejayuu]

The energy efficiency with all the springs seems very low for a .177" HW77.

Have you checked the piston and breech seals?

Thanks for the input. The seals need replacing but the exercise was to compare springs so assumed the
seal would not change that. Probably wrong?

Can you elaborate on the efficiency from figures shown?

[BTDT]

Thanks for the input. The seals need replacing but the exercise was to compare springs so assumed the
seal would not change that. Probably wrong?

Can you elaborate on the efficiency from figures shown?

The muzzle energy appears currently broadly between 25% and 30% of the energy made available to the piston. A 25mm HW77 should be nearer 35% to 40%, if not more, depending on the spring and preload.

[deejayuu]

Gotcha BTDT! Will continue fiddling. Thanks for the interest.