hi. I'm looking for wisdom i happen to be lacking. i shoot benchrest (100-200 yrds) and have done so for some time. i also shoot hi power competition (200-300-600 yrds service rifle) and have just finished a rifle for 600 and 1k yrd bencherest. my question is about the rifle. i took it out to the range (after taking a year to build it) to get my chronograph data and shot groups at 100 yrds. 4 different powder charges all grouped in the 1/4" range. i had 6 rounds left of one powder charge.i shot those 6 at 200 and there were 2 holes in the target .4 center to center. there were 3 bullets in each hole. the holes measured in the .1 and .0's. i have never experienced a rifle that tightens up at 200. the rifle is a hall action, shilen barrel, shehane stock, bob white smithed it and t&m did the stock work. any input is greatly appreciated. all this started because i saw a video of gallon milk jugs being shot at 1k yards and i wanted to join in the fun! thanks in advance for the wisdom.