Airsporter/Mercury power problem

[venoman]

Has any one had problems with Airsporter/Mercury low power using none genuine alloy piston heads. I have had an Airsporter apart 4 time replaced the nylon type head that was sized with a alloy head , new Oring buffer washer and spring . .22cal and its only doing 8 ft lbs , fitted a Titan XS spring and use a genuine BSA O ring still the same. Also i have rebuilt a .22cal Mercury new alloy head , seals spring and barrel seal 9.5 ft lbs ?.

[ZAKDINGEL]

The last one I had I used a ptfe piston head from tr robb I also used one of his springs it sorted the power problem that I had no probs

[LESS THAN FORTUITOUS KENNETH]

I've got an airsporter I've been trying to get right for a couple of years now and am no nearer than when I started. It's had various heads, several o rings, a custom head with Diana seal, various different springs, guides, piston sleeves, longstoked, etc etc. Every possible mod done and no different at the end of it all. Match abandoned. On the other hand, I have a Mercury which I have only cleaned and lubed. Sweet as a nut and doing 10.75 fpe.

[averageplinker]

Is the cylinder bore not parralel or could it have bulged due to detonation leading to poor sealing????
Or is the air getting round the tap instead of through it?

[Shed tuner]

leaking someplace... o-ring heads need a very true cylinder to seal, far less forgiving than a lipped parachute style - as above maybe the cyldinder is dented / bulged / scored

[LESS THAN FORTUITOUS KENNETH]

The tap seems fine. It does point to a problem with the cylinder. Or the transfer port?

[mrto]

8ftlbs is common in later mark .22 Airsporters the MK1 and MK2 are typically better powered.

[peddy]

8ftlbs is common in later mark .22 Airsporters the MK1 and MK2 are typically better powered.

Would have thought around the 500fps to be expected, not many British guns made much more. It's more important that the cock and firing cycle is smooth and twang free and it is consistent. I've tried everything to get my Webley hawk mk2 to make 10fpe apart from machine the piston and the best I could get is 8fpe, but it's now virtually recoil free smooth to fire and very accurate. It's only going to be used for plinking so power isn't priority

[maximus]

Has any one had problems with Airsporter/Mercury low power using none genuine alloy piston heads. I have had an Airsporter apart 4 time replaced the nylon type head that was sized with a alloy head , new Oring buffer washer and spring . .22cal and its only doing 8 ft lbs , fitted a Titan XS spring and use a genuine BSA O ring still the same. Also i have rebuilt a .22cal Mercury new alloy head , seals spring and barrel seal 9.5 ft lbs ?.

Mercury's should make power easier than an airsporter due to the loading tap. I found that how far the pellet drops into the tap makes a significant difference to the power. One of mine leaked so badly that I got the plug machined to add o rings which cured the problem.
The Mercury should make 10 ftlbs plus if everything is OK.

[Jenny Dipple]

Did you de-burr the cocking slot!