I just fitted a new spring to the 1919 Light Pattern.I bought a flat wire spring from John Knibbs thinking it would be the closest to the original type. The wire is a bit heavier than the original and its a bit longer too. I had to take about four coils off this particular one to get it in & it is quite strong. The rifle seems excellent now, shooting nicely, I will let it settle down & then chronograph it.
Here are a few pics:
Preload on Knibbs spring as supplied (I couldn't even get close to getting it in!):
Comparison to (believed original BSA) spring from an well preserved IMD Light Pattern:
(Top Knibbs, bottom Original)
(Left Knibbs, Right original)
Round wire spring from another Light Pattern(This onehttp://www.network54.com/Forum/670541/thread/1312573861/Light+Pattern+L35392
) that shoots nicely.