bullet needing time to stabilize?

So I recently bought a savage based rifle with a Shilen 7mm mag barrel on it. Supposedly it will shoot 4-4.5" groups at 1k if the shooter does their part. I put a Leupold vx3 8.5-25 lr scope on it in Burris Signature rings and sighted it in at about 40 yards since that's the farthest I have currently available. I used the rounds that came with the rifle, but it shoots about 2". I talked to the PO and he told me that I need to shoot a minimum of 150 yards to allow the bullet to stabilize. Does that sound right? Every other rifle I have will easily outshoot this one at this range. I always thought the farther distance you shot at, your groups would widen.

Forgot to mention I have made sure all the screws were tight on the bases, rings, and action

Yup, he is probably correct. It will be easy for you to check. Shoot it at 200 yards! I have seen some rifles shoot a smaller relative group at 200 yards than at 100. For example, a five shot group of 1.2 inches at 100 yards and 1.6 inches at 200 yards.

4"-4.5" groups at 1k is a very bold claim.

Yes, it is true. Long range bullets have a very short bearing length compared to their overall length. No matter how perfect your reloading methods are the bullet will not engage the lands perfectly even. The bullet will stay "crooked" as it gains rpm during it's travel through the barrel.

Once it leaves the barrel the bullet will seek it's own center and stabilize on its axis. It can take a considerable distance for this to happen.

Think of an old school children's top. Wrap the string around it and chuck it on the floor. It will wobble for a bit then it will calm and spin in the same spot until it drops enough rpm to loose stability.

I read sierra's exterior ballistics info in my reloading manual. My eyes only recently stopped rolling back in my head. Lots of tech speak, but the bit I gathered did lead me to believe that bullets do need a bit of time to stablize. This was MY understanding, not saying that is what they were trying to tell me.

I have seen it time and again at the range. 100 yard targets look nice, then the 200 yard targets go bigg. Back at 300yds and beyond groups close up again.

I dont know what causes it, but it does happen. Magic, or Level III gnomes with the abilities to affect trajectories may cause it. Or maybe there is something more tied to science. It doesnt matter. It does happen.

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Originally Posted by geargrinder

4"-4.5" groups at 1k is a very bold claim.

Yes, it is true. Long range bullets have a very short bearing length compared to their overall length. No matter how perfect your reloading methods are the bullet will not engage the lands perfectly even. The bullet will stay "crooked" as it gains rpm during it's travel through the barrel.

Once it leaves the barrel the bullet will seek it's own center and stabilize on its axis. It can take a considerable distance for this to happen.

Think of an old school children's top. Wrap the string around it and chuck it on the floor. It will wobble for a bit then it will calm and spin in the same spot until it drops enough rpm to loose stability.

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GG did a good job of explaining things. I always think of what the arrows do when they come out of my recurve. At ten they would try to go in at a 45, at 20 not bad and by 30 we are cooking with gas.

Well I shot it at about 100 yards and the groups got better. Planning on doing some more shooting as time and weather permits.