Perfect break barrel... for me that would be the Cometa Fenix 400USC in .22 running anywhere between 8.5 and 11.4.*
The only thing these need:
Make sure the spring ends can rotate / fit slippy washers / grease correctly.
Remove the little spacer on the triggers second stage adjustment.

I rate this rifle highly enough that I'm very close to buying a second... in .22.
I've had HW's and yes, Great trigger but on the whole, they're like a Mk2 Ford Escort 1.1... great place to start if your gonna throw money at it and make it something special.

*I will confess that when 'upping' the power, I went over the top with the washers and blimey it can make Serious power And retain its excellent shooting charactaristics.