Ruger Blackhawk Hunter better accuracy?

[Harold Money jr]

I have a Ruger Blackhawk Hunter I shoot reloaded 240gr XTP's, 19.9gr of 2400, standard cci pistol primers and various cases all checked for length. My gun seems to shoot a few bullets in a tight group then the group moves a couple inches like 3 hit dead on then 3 hit 2" higher. Both good groups but not together. We're talking 3" group total. I put a Leupold scope to eliminate iron sight discrepancies but, the same stuff happens. The trigger is good. Things that are on my mind to try are
1) premium factory ammo.
2) barrel lapping
3) numbering the cylinders and recording where they hit
4) base pin upgrade

What do y'all think? I love the gun it just not as accurate as I want.

 

[mr.big]

I like IMR 4227 in the Blackhawks I have loaded for,

 

[Snowwolfe]

Revolvers are tough to diagnose because shooters ability is more important than ever. The first thing I would do is shoot a few groups using the same cylinder chamber each time. I would hold off getting a premium barrel for now.
Do you feel any tight spots in the barrel when pushing a tight patch through it?

Also, if you shoot 3 shots the revolver could easily be shifting in your hand causing the change of impact. Grip is everything.