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Range Report on .375 x .284 Win
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Old 10-16-2008, 02:03 AM
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Default Range Report on .375 x .284 Win

Finally got the gun to a field-ready condition and got to the range. AS I said before, the rifle isn't finished yet, needing bluing and a wooden stock, but it is ready for hunting. SO... I needed to get it sighted in and find a good, precise load. One outta two ain't bad for a start I guess...

After considerable work with QuickLoad I settled on a powder - AA 2495, a bullet - the Accubond 260, Optimal Barrel Timing theory node - 5, and calculated a range of charges - from -1% down from node charge to -3% down from node charge. That range turned out to be from 49.50 grains to 48.50 grains. Divided into 5 increments of 0.25 grains each, I loaded four rounds each of five loads. I also loaded 6 rounds with the Speer 235-grain round-nosed, flat-based bullet for getting 'on paper'.

Getting on paper was quick and easy and the 235s shot well at 25 yds. After 3 shots, I moved the target to 100 yds. I shot the bullets "round robin" in order to minimize any effects fue to shot string order. In other words, I shot one bullet from each of the five loads; waited for the barrel to cool off; shot the next set of five shots of one each from each charge group.

The temperature when I arrived at the range was 34F (1C) and when I left it was 35F(2C). there was a steady wind from the 9 o'clock position of about 10 mph.

Shooting the rifle was a real pleasure. Even from a bench on a cold day, it wasn't unpleasant. Mush better than my .3338 WM, even though the ME for the .375 was a bit more than it is for my .338 WM loads. The .375's extra weight makes all the difference.

As you can see, it ain't great. I really don't know why. The simple points to consider are that the barrel was brand new and these were the first 26 shots out of it. Of course there's the obvious one, being the "nut behind the butt". Possible, but later shots would render that expalanation unlikely. Operator error (again me) in the manufacture of the finished rifle - probably the most likely cause. Could also be that the gun doesn't "like" the 260 Accubond - it is after all, a boat-tail. Could be the charges were wrong. I simply don't know, but I wasn't exactly 'proud' of the groups. There is one subtlety that renders the results not quite so bad though.

If you examine the group in the upper left (the 48.50-grain group), and the group at center bottom (the 49.5-grain group), three of four of the shots are at least "OK". What's important, is that the outlier in both was the first shot from a cold barrel - on a cold day.

Removing the outlier (first shot) from the 48.50-grain group (the lowest (-3%) charge), renders a 3-shot groups with dimensions of 0.804" x 1.300". That's not "bad".

Removing the outlier (first shot) from the 49.50 grain group (the highest (-1%) charge), renders a 3-shot groups with dimensions of 1.745" x 1.530". That's not great, but it is 'tolerable' for the time being.

None of the remaining three groups have outliers whose removal (with justification of being the first shot from a cold barrel), makes any real difference in groups size.

The little verticel 3-shot group at about 4:30 o'clock, is a 0.500" x 1.200" group from the MAI.

From lowest to highest, the average MVs for each four-shot charge were: 2417, 2429, 2440, 2452, and 2463 f/s. Even though the best 3-shot group's MV is the lowest (2417 f/s), it still delivers 2020 ft-lbs to 300 yds. Therefore, I will "work" with that charge and see if I can't tune it a bit and make sure it can consistently deliver about 1 MOA.

I'll have some more thorough statistics for each group sometime tomorrow.

Oh yeah, the target says that the range of charges goes from 45.5 to 49.5. That's wrong. WHat I stated above - 48.5 to 49.5 - is the correct charge range.

Paul
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Last edited by gitano; 10-17-2008 at 03:16 PM..
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