Inside the 1912 BSA Improved D

[jirushi]

Interesting thread, and congrats with your purchase.

I hope it's ok to write the following, as I do not want to hijack your thread, but I thought it is related to your question.
I recently bought a lovely Light Pattern from Binners.
This morning I worked on a new piston seal. The leather washer on the inside of the cup is now a bit thinner, so that the metal washer and screw head are sunk in a bit.
I should have asked if this is the right thing to do first, but it felt so.

Power is up with 1 ft/lbs, to 5 ft/lbs. I think there is room for improvement though.

Does this look about right?