What Mainsprings do people use as replacements? I was at a boot sale this morning and came across a drill bit. New and unused its a 4 flute 55/64" with a 3MT shank. Something in my head rang a bell so I bought it for the princely sum of £10.

got home and sure enough, Chris Thrale mentions in his book that Webley provided a service boring pistons out to this size to accept MK3 springs. I have 5 MkII rifles and took the pistons out to check. The drill fits like a glove in one of them but is just shy of entering the others.

So, What springs do people use, and is there any advantage to opening up the piston to accept the easily available standard Mk3 spring?

All mine shoot well anyway so don't think I will do it yet but just wondered what people think.