Originally Posted by lonzonoscar
This is my first post to this forum. I will be going on a Dall Sheep hunt in 2015 and needed to hone in my long range shooting precision. I am shooting a .300 WSM in a Tikka T3 Lite. I don't reload so depend upon factory bought ammo. After purchasing boxes of ammo from 6 different suppliers, I found my best precision was with Nosler's Custom Accubond-180 grain and HSM's Berger VLD 185 grain. At 100 yards I can get 3 or 5 shot groupings of less than 1" in this factory rifle that I purchased a year ago. This is from a bench. The next step was to shoot at 400 yards using a bench. I thought I would be around 4" or 5" groupings, but found that I am averaging 9" with the HSM and 7" with the Nosler. Can anyone give me some advise on why my groupings are much larger than expected when I went from a MOA of 1 to 4?
First of all...I'd roll with the Nosler ammo for a hunt like that.
Your groups...lots of things effect a bullet, the longer its in flight, the more "visible" these things become on the target.
Also, its harder to hold MOA as the distance grows...some things can help with this though...this why I prefer thin reticles in my scopes...aim small, miss small...but you can't aim small if your reticle covers the target.
You didn't mention your scope...and this is most likely the problem...parallax....most scopes without a parallax adjustment are factory pre-set for 100-200 yards...and even the ones with parallax adjustment, most people don't adjust them properly...the numbers on the parallax knob are pretty much useless, don't use them.
Aim at a 400 yard target, move your head side to side (not moving the rifle)...if the reticle appears to move on the target...you have parallax.
If your scope has a parallax adjustment...forget the numbers on the knob, turn it while moving your head as described above...when the reticle stays still on the target...it is set for that distance, and many are slightly out of focus when set for zero parallax...not so bad that you can't use them, but a little out of focus.