Thread: 1000yrd load???
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Old January 30, 2013, 01:08 PM   #13
Bart B.
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Join Date: February 15, 2009
Posts: 4,707
I've used Varget with different charge weights for 155's in four different .308 Win. case makes/types ranging in weight from 150 grains up to 170 grains with both large and small primers. Accuracy's been about 1/2 MOA at 600 with all of them in two different Palma barrel contours. Therefore, the sweet spot with Varget is more like a sweet range; it's pretty wide. It's been my experience with IMR4064 in .308 Win. cases that it also has a sweet range, not a spot. So did folks shooting it in 30 caliber handloads with new cases in their Garands; 'twas much more accurate than IMR4895. With the right powder, most any round will have a sweet range in my opinion.

I've found that powders with the lowest change in muzzle velocity for a 1/10th change in charge weight give the best accuracy. One way to find one is to look at the velocity change between the 100 fps velocity colums in Sierra Bullet's loading data, or any other that lists loads in 100 fps increments. Some powders cause 50% more increase in veocity with a 1/10th grain increase in charge weight compared to others 15 fps versus 10 fps. Do some comparisons between IMR powders 4895 and 4064; it's interesting.

And yes, stay away from both of Sierra's short tailed 30 caliber match bullets in 168 and 180 grain HPMK styles. Sierra originally made their 168 Int'l bullet with a short, 13 degree boattail for 300 meter free rifle use. It was great for that as well as match rifle use up through 600 yards. Sierra's first 180-gr. FMJBT match bullet had the longer 9 degree boattail as did their first 200-gr. FMJBT match bullet. These were great and when both were changed to hollow point HPMK versions, they shot even more accurate. A favorite use the 180 was to replace the 172-gr. bullet in 7.62 NATO match ammo with it then shoot matches winning them and setting records with M14's on the US Army Rifle Teams. Sierra changed their 180's boattail back to the 168's short one as a cost saving method. The US Army Team (and nobody else, either) no longer got good 1000 yard accuracy and contracted Sierra to go back to the old long boattail making special order bullets for them. Ever wonder why Sierra's 175 HPMK has a long tail? The ballistic engineers at Lake City Army Ammo Plant knew what boattail shape was best so that's what they asked for in replacing the Sierra 168 in their M852 match ammo.

Yes, Unclenick, runout under 3 thousandths is good enough to shoot 1/2 MOA all day long from good .308 ammo in great rifles fired by even better shooters.

Regarding Berger's secant ogive bullets compared to Sierra's tangent ogives on their match bullets and where they rest in the leade when chambered. I don't know if Berger did any tests with leade angles over a wide range to see if one enabled best accuracy compared to a short jump to leade distance their secant ogived bullets often need. I've a gut feeling that a leade angle less than 1 degree might work well with them seated into that leade. Reducing the 7.62 NATO chamber's leade angle is one reason that round shot the same bullets more accurate than the 30 caliber's leade angle; 2.5 degrees down to 1.5 degrees really worked out.

Kraig, case prep, other than turning necks to a .001" spread in thickness and sorting by weight to a 1% spread, in my and that of many other long rangers' opinions, isn't needed. Uniforming and deburring flash holes, sorting to exact weights and trimming to exact lengths has never proved to be mandatory. But it does make some folks feel better and nobody shoots better than they feel.
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Last edited by Bart B.; January 30, 2013 at 01:36 PM.
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