Mk1 Airsporter S Power Problems.

[WoodsmanJim 160]

Hi All,

 

A friend of mine has a Mk1 Airsporter S which seems a bit down on power. He's recently dusted it off after a long lay up in the attic and it seemed to be firing well. Still fairly accurate and, based on firing side by side with my HW90 and comparing pellet speed and impact noise on the target, seemed to be making good power. It was then mistakenly fired dry with the pellet tap in the up position. since then it seems down on power and sounded different. we put it over the chrono again and sure enough it was down from 520fps before the dry fire to around 490-500fps. I'm thinking the piston seal may have been damaged? It is quite old so that wouldn't be a surprise!

 

If anyone has any other theories or tips and advice about stripping and servicing these old classics, I'd be very appreciative!!

 

Many thanks,

 

Jim

[paulus 26]

diagram of parts https://www.gunspares.co.uk/products/24691/S/

[barrywhite 282]

If we assume the old leather washer is ok, maybe it has expanded a bit and got a bit tight and will go back to what it was in time .Or the old leather washer was / is almost finished and shooting the gun with tap open has finished it of ...If the gun piston feels slow when shot,a tight main washer ..maybe ..if the piston now feels fast a damaged main washer ...maybe it is no longer trapping air allowing the piston to move faster.