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Rifles, Reloading, Optics, Equipment
Reloading
308win load help.
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<blockquote data-quote="Bart B" data-source="post: 1126006" data-attributes="member: 5302"><p>First off, I think 46 grains of Varget under a 168 in a .308 case is a bit too hot. Unless your bullets are under size and the bore's over size.</p><p></p><p>Your tests have demonstrated what I've observed over the years shooting few-shot groups; 5 or less shots in each. In my opinion, yours are all statistically equal. A few grains spread in charge weights for 168's in all the .308 Win barrels I've worn out with Sierra's 168's show insignificant difference in accuracy through 200 yards with several makes of powders, primers and cases. Doesn't matter if each load shoots to a slightly different point of impact relative to the aiming point; that's normal and adjusting the sight will fix that. And the bullet's jump distance to the rifling increased about .070 inch from when the barrel was new to some 3000 rounds later as the throat advanced from wear and all rounds had the same OAL length.</p><p></p><p>If your marksmanship qualities are good enough to shoot different loads into 1/2 MOA or thereabouts at 100 yards hand holding a bag-rested rifle to your shoulder, quit testing loads and pick one at random and start shooting for fun instead of testing.</p><p></p><p>Should someone shoot several dozen 5-shot groups with any load, they'll typically have a 3X to 4X extreme spread from the smallest to the largest group. And the smallest group is rarely the first group shot.</p><p></p><p>You're effectively rolling several pairs of dice when shooting groups. Each pair will average 7 (zero in their spread) and a few boxcars (12's, maximum spread) as well as a few snake eyes (2's, minimum spread). Each pair represents the variables in each of the three parts of the shooting system; you, your rifle and your ammo. Smallest groups happen when all the variables are at their minimum, or cancel each other out. Biggest ones happen when they all add up in one direction. And humans holding onto rifles typically have the variables with the biggest MOA values in pointing the barrel at the same place from shot to shot.</p><p></p><p>Dozens or hundreds, if not thousands of rifle ammo testers will disagree with the above. So be it.</p><p></p><p>For those wanting to see how 5-shot (or 10-shot) group sizes vary across several, go to this web site then download each match's file, open it and see how the top ten's group sizes varied across several of them. As well as how they varied at different ranges.</p><p></p><p><a href="http://www.benchrest.com/showthread.php?93618-2015-NBRSA-Nationals-Complete-Results" target="_blank">http://www.benchrest.com/showthread.php?93618-2015-NBRSA-Nationals-Complete-Results</a></p></blockquote><p></p>
[QUOTE="Bart B, post: 1126006, member: 5302"] First off, I think 46 grains of Varget under a 168 in a .308 case is a bit too hot. Unless your bullets are under size and the bore's over size. Your tests have demonstrated what I've observed over the years shooting few-shot groups; 5 or less shots in each. In my opinion, yours are all statistically equal. A few grains spread in charge weights for 168's in all the .308 Win barrels I've worn out with Sierra's 168's show insignificant difference in accuracy through 200 yards with several makes of powders, primers and cases. Doesn't matter if each load shoots to a slightly different point of impact relative to the aiming point; that's normal and adjusting the sight will fix that. And the bullet's jump distance to the rifling increased about .070 inch from when the barrel was new to some 3000 rounds later as the throat advanced from wear and all rounds had the same OAL length. If your marksmanship qualities are good enough to shoot different loads into 1/2 MOA or thereabouts at 100 yards hand holding a bag-rested rifle to your shoulder, quit testing loads and pick one at random and start shooting for fun instead of testing. Should someone shoot several dozen 5-shot groups with any load, they'll typically have a 3X to 4X extreme spread from the smallest to the largest group. And the smallest group is rarely the first group shot. You're effectively rolling several pairs of dice when shooting groups. Each pair will average 7 (zero in their spread) and a few boxcars (12's, maximum spread) as well as a few snake eyes (2's, minimum spread). Each pair represents the variables in each of the three parts of the shooting system; you, your rifle and your ammo. Smallest groups happen when all the variables are at their minimum, or cancel each other out. Biggest ones happen when they all add up in one direction. And humans holding onto rifles typically have the variables with the biggest MOA values in pointing the barrel at the same place from shot to shot. Dozens or hundreds, if not thousands of rifle ammo testers will disagree with the above. So be it. For those wanting to see how 5-shot (or 10-shot) group sizes vary across several, go to this web site then download each match's file, open it and see how the top ten's group sizes varied across several of them. As well as how they varied at different ranges. [url]http://www.benchrest.com/showthread.php?93618-2015-NBRSA-Nationals-Complete-Results[/url] [/QUOTE]
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