Have you done any trigger work, like Arrowdodger mods ? I have a 2014 Mayfield Model-60 and the trigger was about 5-6 lbs. when I bought it last year (NIB-an unused closet queen). I did most of the Arrowdodger mods and got the trigger down to about 2-3#. I was just out y-day and shot 8 diff brands of SV & HV. The worst was about 3" (Herters bulk HV) and the best was under 1" for 5-shot groups (S&B SV). I only shot 15-30 of each brand so not really definitive, but a good idea of what it likes. And it was 1-2*C with a 5-10mph tail wind that prob pushed them around a bit. Also, as was said you should check the muzzle and maybe run a brush on a drill in the chamber a few seconds. Could be you have 'Carbon Ring' clogging the leade. If you know someone with a borescope you should look inside. Those are only about $70 on Amazon - Teslong 0.2" diameter - lets you know how well (or not) you're cleaning.
