Ailing Airsporter

[piggy589]

Or is it?,a recently acquired S model producing around 650fps with 7.9grn accupels.

The mainspring appears standard and in good nick at around 250mm and 33 coils.

The piston head has a new replacement seal and decent buffer fitted.

But the pellets do seem to be a rather loose fit in the loading tap.

Any thoughts,or indeed input, would be much appreciated .

[Hsing-ee]

Mercurys and Airsporters often suffer from 'O' rings which are too tight a fit in the compression chamber bore. The cure is to fit the smaller 'O' ring from the BSA Meteor, or if you have a collection of 'O' rings, one which is not such a tight fit. Also, the 'O' ring has to be in good condition, it is easy to knick them as they are fitted. Use old-type camera film to ease the 'O' ring in. If the spring is in good condition and the piston seal is sealing and a good fit, you should get between 10.5 and 12 fpe depending on pellet from an Airsporter in .177. I think the later S model increased power by using a steel piston head - less bounce with a stronger spring perhaps. As you say, it might be an idea to try some other pellets, JSBs, H&N FTT and RWS Superfield would be my first choices.

[piggy589]

Thanks bud,the seal on the metal piston head came out of our air-con. selection box and is a nice sliding fit.

As you suggest it might be an idea to test a range of pellets to find one that fits snugly in the breech plug.

[Hsing-ee]

Thanks bud,the seal on the metal piston head came out of our air-con. selection box and is a nice sliding fit.

As you suggest it might be an idea to test a range of pellets to find one that fits snugly in the breech plug.

Other than the seal, if it is still a problem then there is a chance the tap is misaligned - shoot into some loosley packed cotton wad or something that wont deform the pellets and see if they are going into the bore squarely. Check that the piston rod is straight. GOod luck !

[piggy589]

I made a point of looking through the stripped action from the rear to check the tap alignment.

All appeared to be correct,there again there's nothing to say the tap to action gap isn't allowing air to escape.

From memory this is acknowledged as the Airsporter's achilles heel,a flawed design.

[DAVALI]

Use a dome ended pellet probe to seat the pellet in the bottom of the loading tap, I've found this improves consistency and power on all my tap loaders.

DaveM.