country boy,
Thanks for reminding me of the specifics about the rifle, etc.
Some other people on this thread have also said that the two things they've seen open up groups at longer ranges are wind (especially), and to a certain extent scope parallax--though parallax normally has a far greater effect beyond 200 yards. In fact that was the very first response to your post. Do you know how to check for parallax?
I'm still doubtful about the wind, mostly because I've actually measured wind a lot. Most shooters have very little idea of wind velocity unless they do, and also don't understand how much it can affect bullet drift, even at relatively short ranges.
Combining a little parallax and wind drift can make a considerable difference, even at 200 yards.
You also mentioned that your groups at 200 were scattered side to side, while your brother's were more vertical. Somebody else mentioned a slightly canted reticle as a possibility, but this shouldn't affect group side IF the reticle is aligned with a vertical line on the target the same way for every shot. But if not, at 200 yards, tilting the rifle from shot to shot, even slightly, can make considerable difference. In fact it can make considerable difference even at 100 yards, especially with a relatively high-mounted scope. I have a buddy who was having enormous problems getting a new lightweight rifle to group accurately, and he eventually asked me to help. He'd mounted a scope with a pretty big objective, which required high mounts--and it turned out he was tilting the rifle a little, differently for each shot. I coached him some, and the problem went away.
You've also stated the rifle was rested on sandbags, front and rear. Was the same rest used both at 100 and 200? Did you check to make sure the front sling swivel stud was sufficiently in front of the bag to not bump it during recoil? Did you rest the forend on the same place every time? Some rifles can definitely be affected by forend placement.
Some relatively lightweight rifles can also be affected by the hardness of the front rest. Even sandbags can be compacted hard enough to affect groups after some shooting. With lighter-weight rifles I've found a folded towel over the front rest can make a big difference in group size, as was recently discussed on another thread.
MD, Thanks for all of these suggestions. This is exactly the kind of information and recommendations I've been looking for. I appreciate constructive criticism without treating people like they are an idiot, as I have seen so often by others. I think I would almost rather find out that I'm the culprit than it be a rifle or scope problem......
During my next range trip, I will pay particular attention to the sling studs placement, both front and back. I will also check the wind more closely. I spent a great deal of time checking the original scope (VX5) for parallax and playing with the adjustments, but could not see any problems as it was set. Both scopes have the adjustable ring on the eyepiece.
