Having finished my LP53 mods for now, I thought I would compare some different pellets in respect of velocity. So a bit of fun for now with no interest in SDs or accuracy at this time.
I'd read that Air Arms pellets suited these barrels and as the postman brought some this morning, I thought I'd get right on it...

Results:

RWS Geco 7.3g 495 fps
AA Diabolo Match 4.49 8.02g 470 fps
AA Diabolo Express 4.52 7,87g 475 fps
Bisley Practice (H&N) 8.3g 450 fps
H&N Excite Econ II 7.6g 460 fps
Sig Sauer Dagger Copper Coat 7.2g 440 - 490 fps
Skenco Hyper Velocity 5.9g 530 - 580 fps

The last two pellets tested were too inconsistent to give a meaningful average!
The Geco, although an economy pellet, appear well made and are quite consistent so I will probably get a few more tins of those.

Steve.