stabalizing question

recon762

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Minuteman
Feb 28, 2008
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Bozeman,MT
Question for you reloading goroos. I have a AI AE 20in barrell i heard they dont like heavey bullets say 175s i loaded 44 grains R-15 and sierra 175s and my AE put five in one hole i was more than impressed. My question is i know they are stabalized at 100 with that kind of group but does that mean they are stabalized at say 500 600 700 a 1000. so i guess im asking if a bullet is stabalized at 100 does that mean it will also shoot good at extended ranges thanks guys
 
Re: stabalizing question

Not necessarily. It might be on the very edge of stabilization at 100yds, and may become unstable at longer ranges, although I doubt it in this case.

I'm not sure what twist the AE has, but from my experience running a 1:11 short barreled (20") .308, the 175's have never been a problem at any distance I care to shoot them at.

This is at 6500' asl minimum here in Wyoming.
 
Re: stabalizing question

It is going to depend a lot on the muzzle velocity. If you got them between 2700 and 2800 fps at the muzzle, you're probably going to be good to go. (You are close to my 1K load for 175 Bergers. My rifle has a 24 inch barrel.) Some boat tail bullets don't fully stabilize until 200 to 250 yards or more. If the projectile has become stable in flight at super sonic velocity, it should not become unstable until it goes through the trans sonic area. Shortly there after it will start to yaw and pitch again as it becomes unstable. You may see "keyholing" again in targets at extended ranges.

I'm going to make a guess and say that unless acted on by other forces, that load won't start keyholing until 1100 to 1200 yards. (If it is in fact at the velocity I stated above.)

The longest range I've fired my 308 with those bullets was 1250 yards and SOME of the bullets were keyholing. If I remember right, about 6 : 10
 
Re: stabalizing question

First, I know that your AIAE won't have any problem stabilizing the 175 grain bullets. It should have the same twist as my AIAW, which is 1:12. I have shot the 208 bullets from my AIAW and it stabilize the bullet nicely up to 1000 yards. Capable of going further, but don't have the opportunity to do so.

Speed is going to be your nemesis. If you can get it up to reasonable speed, like Victor pointed out, in the range of 2800 fps, then you are GTG. Now, just because a load that shoots bughole at 100 yards, doesn't mean that it will do the same at 300, 500, and beyond. That's the fun and frustration of working up a load. Bottom line is you don't know until you shoot it. And don't forget to have fun while doing that.
 
Re: stabalizing question

Bullets become more stable as they slow down (and the rotational velocity stays the same) until they start to approach the speed of sound.

Rotational velocity is set by the twist rate of the barrel and the Muzzle velocity. Thus, if the bullet is stable for the first 100-200 yards, it will remain stable down to the sound barrier.