SuperKirby
You are shooting your Pro-Hunter correct?
Did not realize also that you were shooting open sights... if so you might well run out of ramp before you are able to get to the correct elevation...
Check your front sight, can you push the front blade out... is it dove tailed in or is the front sight all one piece? If you have a dovetail you may well want to push that one out and go with a shorter blade to raise the muzzle.
If you have a mic you can measue the height of the current sight and them go down from there... There is a possiblilty that the sight height is stamped on the bottom of the sight also.
Are you going to be using the open sights for hunting or are you planning on scoping the gun???
I get very good accuracy with a 300 grain bullet and 110-120 grains of BH or T7.
Keep after it you will get it...