Re: 100 accuracy good, 200 not
Alot of shooters think. "well if my rifle shoots an inch at 100 yards then it should shoot 2 inches at 200 yards". When nothing could be farther from the truth.
Shooting at 100 yards is only a good test of accuracy for a rifle that will be shot at 100 yards or less in the woods.
When I test loads for my varmint rifle I am concerned about the 300 yard groups. The 100 yard groups are totally irrelevant.
Now when shootnig longer range that is when you separate the wheat from the chaff.
When shooting longer distance it takes the skill of the shooter, as well as the quality of the equipment. If both aren't up to par then long distance accuracy will suffer greatly.
It could be a dozen reasons. Basically an inaccurate rifle, bad shooting, poor stock design, poor load performance..................and on and on.
Start with your shooting. Do you know anyone with a rifle that you personally know will shoot 2" groups at 300 yards?? If so then spend some time behind that rifle. What groups do you shoot from that rifle??
There is no replacement for practice and quality equipment.
Personally I do not believe the power of the scope is very important. I have shot 3X9's to 400 and 500 yards for years. No problem with the power, just as long as the scope qualtiy is there.
Basically you asked a question that can not be answered on the internet. It has to be done at the range. And with many shots fired down range. Practice is the only rememdy, along with better equipment.
My first suggestion would be about your trigger, and trigger control. Tom.