I'm starting to wonder if the way I was holding the rifle is the culprit.
That can sure make a difference! If your gonna do serious load testing you'll have to get your bench technique down to a science so you can concentrate on the loads instead of everything else. Eliminate variables as much as possible. Get yourself a descent front rest, get comfortable with it. Make sure the sling stud on the front of the stock isn't hitting and (for lack of a better word) bouncing around the rifle. Every shooter is different but I preferred to use free recoil for all my load testing. Get yourself a descent back bag also! Don't rely on the ranges canvas sand bags. Get your own setup and get real comfortable with it.
Your cheek weld can also make a difference and cause small parallax errors if you mount the rifle different each time you test a group. You can test parallax by mounting the gun as normal, watch the crosshairs and the bullseye. slowly move your head around and if the crosshairs are moving, you've got parallax. Play with your front adjustable objective until you can dial out the parallax. The yardage settings are usually off a bit on the Adjustable Objective.
Some ranges I've seen connect the benches together with lumber so you can stand your rifles like in a gun rack. These really suck for load testing as everyone down the line can cause all kinds of movement to your bench just by fooling around on theirs. One range even had the roof connected to the benchs and every time the wind would blow you could watch your crosshairs moving around! lol
Anyway there's a lot of things that can give ya a fit at the range and spoil your range testing and like I said, a 1/4 moa problem can be hard to find. If you have any benchrest matches going on in your area, it's a great place to learn. Those guys seem to love teaching and helping folks out in hopes you'll be joining them sometime.
