Thanks Roy.
The Mk.II rifles do indeed need trigger work to bring out their best:
principle reason for the redesigned trigger in the Hawkeye as I understand it.

That particular rifle was a one-owner safe-queen when I acquired it, in near new condition. I followed a recipe I found on-line for stoning the trigger sear surfaces, and replaced the rebound spring with a lighter one: a shortened Bic Biro spring!
Trigger is now just how I like it, and has never let me down. I did acquire the correct replacement spring set (from Brownells?) many years ago, just in case, but the Bic continues to function perfectly.