groups at 400 yards

[dakotah]

The groups, it would seem aught to be linear. But sometimes it isn't so. I suspect that bullets not perfectly balanced may explain the first example. I have seen a rifle that shoots almost as tight a group at 200 yards as at 100 yards. (It was a 35 whelen shooting a Hornady bullet at about 2700 fps from muzzle. Sorry, don't recall the bullet weight though.) That was a very fine shooting Whelen by the way.

If you shoot bullets out of the magazine and the bullets have a soft tip, the ballistic coefficient changes. At 100 yards the point of impact may not be as affected as at 400 yards. Thereby making the group size larger than the linear estimation/calcualtion.

If there is a large varition of velocity, I believe that the further the range the more effect this varition has more so than the linear estimation/calculation would give you. I believe that you will see this most often in long range black powder rifles for instance.

Then there is the condition when a bullet goes sub sonic, the group size may also be altered.

As a general rule you could probably figure the linear rule though. I have gone hunting with a rifle that should hit dead on at 300 yards and I did not check it. I never had problems doing that.

But if you want to be sure measure it!!!