Ailing Airsporter

[Hsing-ee]

Thanks fellas,in an old post someone suggested using BSA's own Storm pellets, as they raised the power of his old tap loader from 7 to 10ft/lbs.

Presumably a snug fit in the tap and bore .

There is no way that a crap pellet should lose you more than three fpe. The Airsporter S should do well over 11 fpe in .177, not 7.5. Just look at the size of the compression cylinder and the spring, my HW30 does 7.5 fpe in .177 and that is a midget compared to the sporter. The bore is the same in .177 as now, it is only the .22s that are slightly over, and even then it is a matter of accuracy rather than power that suffers. Something is seriously out of kilter with it. Try using RWS Superfield and have another look at the piston washer.

[piggy589]

There is no way that a crap pellet should lose you more than three fpe. The Airsporter S should do well over 11 fpe in .177, not 7.5. Just look at the size of the compression cylinder and the spring, my HW30 does 7.5 fpe in .177 and that is a midget compared to the sporter. The bore is the same in .177 as now, it is only the .22s that are slightly over, and even then it is a matter of accuracy rather than power that suffers. Something is seriously out of kilter with it. Try using RWS Superfield and have another look at the piston washer.

Cocking the gun with the loading tap open and then closing it produces a hiss as air is drawn into the vacuum created.

Suggesting to me the new replacement piston seal is doing its job.

As you say the swept volume alone should produce over 11ft/lbs.

Hell,I've got a couple of sixties Meteors,.22 and .177, both nudging 11.

[Hsing-ee]

Cocking the gun with the loading tap open and then closing it produces a hiss as air is drawn into the vacuum created.

Suggesting to me the new replacement piston seal is doing its job.

As you say the swept volume alone should produce over 11ft/lbs.

Hell,I've got a couple of sixties Meteors,.22 and .177, both nudging 11.

The seal might be good but one Mercury I had was the same, a good seal but the friction of the O ring was slowing the piston down a great deal. The other thing is that sometimes they can be over-sprung, causing piston bounce which reduces power. It's a conundrum to be sure. The game is not helped by the unpleasantness of stripping them and building them, always found them the most difficult to re-spring due to the odd shaped back block and the amount of preload they have.

[mallyally]

my mk 2 does 100 fps less with jsb pellets than it does with superdomes its .177

[Shed tuner]

my mk 2 does 100 fps less with jsb pellets than it does with superdomes its .177

yup, seen that on an old HW35 too. Bore/tap fit is critical, especially on older guns...

I'd defo try supersomes as they are very much on the large side of .177 !

[piggy589]

yup, seen that on an old HW35 too. Bore/tap fit is critical, especially on older guns...

I'd defo try supersomes as they are very much on the large side of .177 !

Remind me to dig a tin out,and .177 superdomes weigh? .

[LESS THAN FORTUITOUS KENNETH]

Superdomes 8.3. Superfield 8.4.

[piggy589]

The seal might be good but one Mercury I had was the same, a good seal but the friction of the O ring was slowing the piston down a great deal. The other thing is that sometimes they can be over-sprung, causing piston bounce which reduces power. It's a conundrum to be sure. The game is not helped by the unpleasantness of stripping them and building them, always found them the most difficult to re-spring due to the odd shaped back block and the amount of preload they have.

A friend who seems to have some success tuning older guns thinks it's over sprung.

He suggested fitting a lower power spring,but also adding a piston weight.

Sounds good,that trigger block is indeed a swine to fit.