Its a common power lever for that gun. Many people tune FAC versions down to 12ftlbs and then of course there is the actual 12ftlb variant. Depending on how old it is it could also be a smaller piston gun. What's the serial number?

It could also be a 15ftlb gun with an issue. You can check the breech seal easily but the rest you'd have to do be feel without tearing the gun down. Could be a worn piston seal or spring. Hard to say.
 
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Hey Jimmy,
That's 12 FPE ....... which is on the low side, but also fine. should have a smooth shot cycle.
Just depends what your looking for? In .177 caliber you should be able to get 13/15 FPE, but the caliber restricts power a bit.

By law, all guns in the UK have a 12 FPE limit.

I'm sure the gun could be tuned up a bit using a more powerful spring and/or a new piston seal, but that's up to you.
More power usually brings a more recoil ....... power vs. recoil tend to be directly related on a sliding scale.
 
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Hey Jimmy,
That's 12 FPE ....... which is on the low side, but also fine. should have a smooth shot cycle.
Just depends what your looking for? In .177 caliber you should be able to get 13/15 FPE, but the caliber restricts power a bit.

By law, all guns the UK have a 12 FPE limit.

I'm sure the gun could be tuned up a bit using a more powerful spring and/or a new piston seal, but that's up to you.
More power usually brings a more recoil ....... power vs. recoil tend to be directly related on a sliding scale.
12 fpe limit with 8.44 pellets IS 800 fps. thats running hot and most of us WFTF shooters shoot 8.4 at 785ish. 7.9's however we run up to about 815 fps....
 
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Hey Jimmy,
That's 12 FPE ....... which is on the low side, but also fine. should have a smooth shot cycle.
Just depends what your looking for? In .177 caliber you should be able to get 13/15 FPE, but the caliber restricts power a bit.

By law, all guns the UK have a 12 FPE limit.

I'm sure the gun could be tuned up a bit using a more powerful spring and/or a new piston seal, but that's up to you.
More power usually brings a more recoil ....... power vs. recoil tend to be directly related on a sliding scale.
By law, all guns the UK have a 12 FPE limit.

with an FAC full power levels are allowed
 
If this gun were mine (I have a lathe), I'd buy a ARH Hornet spring, make a top hat and spring guide for about $25/$30 total (free labor).
If the gun then shot a little hot, I would then clip or heat and compress two coils to soften the shot cycle. Maybe 3 if needed.
I've removed or compressed two coils many times which usually, very minimally affects velocity ..... while greatly improving shot cycle characteristics.

Tuning the gun to be in balance, given it's design ........ is everything.

The original HW77 was never meant to be a powerhouse, just a well mannered 12/14 FPE gun.
 
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