BSA Standard Pattern struggling to make good power

[jirushi]

Traditional British craftsmanship; I must practice!
However, a lot can be done with some diamond files, a small hammer, and a sixpack of Leffe!

Some news from Wouter:
after reducing the size of the leather piston seal, as kindly recommended above, velocity went up from 440 to 490 ft/s.
Not bad. Not good enough though, imo. Also, Wouter now describes the gun as twangy.
I recommended to drink a 500 ml Bavaria beer (absolute cowpiss, but it comes in a steel can) and use that for a piston sleeve. Perhaps not the most durable solution, but it worked in my Meteor.

Could his spring be too long/strong? Is there something like an oversprung gun giving less power than when a shorter, correct spring is fitted?

Also, he hasn't used neatsfoot oil yet. Perhaps that will up power; yes, it must make the leather softer, and thereby increase its sealing capacity.
I think

[Garvin]

Traditional British craftsmanship; I must practice!
However, a lot can be done with some diamond files, a small hammer, and a sixpack of Leffe!

Some news from Wouter:
after reducing the size of the leather piston seal, as kindly recommended above, velocity went up from 440 to 490 ft/s.
Not bad. Not good enough though, imo. Also, Wouter now describes the gun as twangy.
I recommended to drink a 500 ml Bavaria beer (absolute cowpiss, but it comes in a steel can) and use that for a piston sleeve. Perhaps not the most durable solution, but it worked in my Meteor.

Could his spring be too long/strong? Is there something like an oversprung gun giving less power than when a shorter, correct spring is fitted?

Also, he hasn't used neatsfoot oil yet. Perhaps that will up power; yes, it must make the leather softer, and thereby increase its sealing capacity.
I think

I think it was Ed who once said that the seal size was the right when the piston would drop slowly in the cylinder under its own weight (and the force of gravity) and stop when you put a finger over the transfer port (ie closed the BSA's loading tap). When the compressed spring is released, obviously the piston seal opens up parachute-style to form an air seal...