groups at 400 yards

[hofts]

for you guys in the know,,, i was wondering, if my groups are 2" at 100 yards with a semi auto 300 win mag, approx what would my groups be at 400 yards, all things being equal and me doing my part. thanks

[denton]

No better than 8". For most rifles, and most conditions, group size increases linearly with distance, provided the wind is perfectly calm...which it usually isn't.

If you have a very accurate rifle, you will see groups get a little vertically egg-shaped at 500-1000 yards, due to variation in muzzle velocity.

The wind is the big factor in spreading groups horizontally. That effect is cumulative as the bullet travels, so it increases more rapidly than just a simple linear curve.

[skb2706]

Best way to find out........set up your 100 yd target at 400 yds. Shoot it and see. It will be exactly four times harder to see....that part is linear. Add in the fact that the bullet will be in flight longer, the drop is parabolic and your optics that work great at 100 yds. fail miserably at 400 yds. You would be extremely lucky to get linear results.

[M.T. Pockets]

I agree that the only way is to measure off 400 yards and find out. I sight my .300 Win. dead on at 200 yards. On a still day it groups from 2" - 4" at this range, if I'm shooting well.

Step back to 300 yards and the group opens up a bit and moves down about 8". A 10 mph crosswind will also move the bullet a few inches at this range. I'm still very comfortable shooting at 300 yards.

Moving to 400 yards is a big step from 300 yards. The group will open up to about 12" and down about 24" - 28". I've found that most ballistic charts are a bit too proud of the trajectory at longer ranges and the drop is more than they say.

A 10 mph wind could move your group quite a ways. Make sure you have a big target. I'd say shooting at 400 yards is at least twice as hard as shooting at 300.

I'm just a hunter that likes to shoot a lot. I know target shooters that can shoot much, much better at that range. But they've worked extremely hard over a long time to get that good, and they have better equipment than my factory rifle & ammunition.

Have some fun and get out there and shoot for yourself at 400 yards, you'll have some fun and it's good practice.

[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!!!