Re: 338 Edge
I would have to agree with Shawn in that if your barrel is a 1-10 twist you should never see a problem with stability at any of the velocity range you should be using the Edge at.
Couple questions. I assume this is a match grade barrel that was new when the rifle was built??? Or was it a factory barrel rechambered to the Edge??
What I am getting at is if it was used, make sure the bore is completely free of copper and carbon fouling.
A good build up of either ahead of the throat can cause what you are seeing but I would say this is unlikely.
I also feel this is a mechanical issue. How did you measure your twist rate in your barrel. If I had to guess just reading the behavior of your rifle, I would say you have a 1-12 twist assuming everything else is set up properly.
Just curious how you measured your twist rate.
Like Shawn mentioned, check out the usual suspects, crown, brake and such.
If all checks out, I would seat those bullets to within 10 thou of the lands or even touching and drop back to 85 grains and work up from there.
One other reason for this may be that you have a loose bore. What brand of barrel is it if it is a custom pipe. I have seen exactly what Shawn has discribed many times with barrels with larger then nominal bores. They really start to shoot good at very upper end loads. The reason, in my opinion is that they need a serious kick in the rear to bump the bullet base up to fill the bore properly and this results in better consistancy and accuracy.
A bullet such as the 300 gr SMK has a relatively stout jacket and needs a good slap in the rear with high pressure to bump it up in a looser bore diameter.
This would be fairly uncommon with the top end match barrels but could happen.
If the upper end loads do not solve your problem, Just to prove the theory, get some 250 gr SMKs and see how they shoot. If they stay on point and the 300 gr SMK will not, I would almost bet you have a barrel that is not exactly 1-10.
BAscially test one thing at a time to eliminate it as a reason for the problem. That way you will be able to see exactly what effect each has on the rifles performance.
Keep us posted.
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