The MkII triggers can be ground and polished down to a better pull. I wouldnt try it if you arent mechanically inclined. I have 3 MkII rifles, and one of my triggers is down to around 2lbs.
Which stock is on the gun ? How many different loads have you tried in it ? Handload or factory fodder only ?
All 3 of mine are 1/2" shooters.