Re: More about 208 AMAX
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sandwarrior</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mavrick10_2000</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: colt933</div><div class="ubbcode-body">So I backed off the lands .010" and reduced my charge from 78.9 to 78.6 grains of H1000.
I don't know if it's the warmer weather, or the change in pressure spike based on not jamming the bullet into the lands anymore, but my accuracy is still 1/2 - 3/4 MOA and the velocity has surged to 3020 - 3050 fps.
I thought the H1000 powder was fairly temperature insensitive. So what gave me this 150 fps jump in velocity?
Also, I have around 500 rounds through the barrel now. </div></div>
Jammed you might have been approaching or at max pressure, and it actually loses velocity at a certain point. By not jamming you can gain back some velocity. That's my guess based on your info . H1000 is pretty insensitive to temps.
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+1
That is the same principle the 5.56 uses to get more velocity than it's civilian brother/cousin. By giving it that free jump, the bullet gets a run at the lands. Meanwhile the case never experiences that high/sharp peak pressure as when you seat into the lands.
Personally, I believe that on most bullets, seating into the lands is the way to gain accuracy. It's been a benchrest standard for a while. This is done by guys consistently shooting under .1's! But, the inverse applies here. Do you need to shave accuracy down to that on a tactical rifle? No.
The other plus thing is when you find the right load making the jump can still be incredibly accurate. I found this out with a .257 Weatherby I used to own. I found this thing could shoot .5 moa groups with the right loads (and bullets) while making better than a 1/2" jump to the lands! So, making the jump doesn't have to affect accuracy, you just experiment until you find the right harmonic load for that jump. Finding the right load also included seating depth, BTW. My .257 Wby worked best when seated to minimum length. Believe me when I say I lost some hair over how to get it to work too. I couldn't seat the bullet out to the lands because it was so far. Making the jump and finding a load to fit that was the only way for it to work. When it did it worked beyond my imagination.
Try that with the .208's in your rifle. You've already tried H1000, so load off the lands and try more/less of that. Also try RE-22 and RE-25. Ramshot Magnum as well. I've used that in 7mm Mag and WSM and .300 WSM and .300 WM. It works well but is more temp sensitive than most powders. </div></div>
With this rifle, I used the ladder test for the first time, following the instructions in the stickys in the reloading forum. So I jammed the bullet into the lands. I got to 3/4MOA accuracy at max pressure loads, but my velocity was around 2875 while I saw so many other people claiming 3000+ with the same bullet and powder combination in the 700P.
But other people here say that the 208 AMAX does not need to be jammed and may be more accurate with a jump based on its secant ogive design. Thus far, I have found more accuracy with the bullet jammed .010" and more velocity with it jumping .010". I am in the process of trying some reduced charges with the .010" jump. Next I will try 78.0 and 78.5. My accuracy load has been 78.9 but jammed .010".
