.338 MAI Range Report

Started by gitano, July 02, 2008, 09:10:10 PM

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gitano

AS I said in another post, the stars aligned today and I was able to get to the range with what I think is going to be my 'go to' load for my .338 MAI. To recapitulate: I had a devil of a time getting everything to work correctly on this rifle when I first started load workup. Fnally, last range trip everything settled back down and all four bullets (180 Ballistic Silvertip, 200 Ballistic Silvertip, 210 Partition, 225 Hornady), shot produced pretty good groups. The best of the bunch - but not by too much - was the 225 Hornady. So... after doing some number crunching, I decided that I'd work on loads for that bullet. The load I settled on is:
 
56.21 grains of Ramshot Hunter (104.4% of case capacity) with bullet seated 0.479" deep (to center of cannelure). Average muzzle velocity was 2563 f/s, producing 3,282 ft-lbs of muzzle energy, at an estimated 50,777 PSI max chamber pressure.
 
I was fiddling with the "removability" of the Warne QD rings and took them off the rifle and them put them back on. I don't know about anyone else's rings, but this caused mine to be off aim by 7" low and 7" wide. :frown Fortunately I brought plenty of ammo.
 
Below are three, 3-shot groups. All three are ~1" in the largest dimension. The first one is before windage adjustment. The second is after windage but before elevation adjustments. The third one is after windage and elevation adjustments. The third group was shot from a barrel too hot to handle, just to see how the rifle shot 'hot'.
 
Paul
Be nicer than necessary.

gitano

These three groups can be combined by subtracting the mean of each group from each individual shot's location. In other words, compensating for the different 'scope adjustments. Doing so puts all nine shots into a rectangle that is 0.938" x 0.896". (It's essentially a square as the difference between the x and y values is only 0.042".) The diagonal of that rectangle is 1.297".
 
Using all nine shots to predict where 95 out of 100 shots would land yields an ellipse whose x-axis is 1.64" and whose y-axis is 1.55" and having an area of 2.00 square inches. In other words, based on the distribution of these nine shots, if I was to shoot another 100 shots, 95 of them should land within ~0.8" of the point of aim (at 100 yds). 99% of them should land within 0.9" of the point of aim. That's good enough for me for big game animals out to 300 yds.
 
Paul
Be nicer than necessary.

Paul Hoskins

Geez Paul, that's really good for a larger caliber. I see nothing that can be improved much. You're not gonna miss with that kind of load in your rifle unless it's operator error. It is a hunting rifle and not a bench gun.   .....Paul H

gitano

That's my thinking Paul. Provided no wierd "mystery" developes like it did two years ago, HB and I should be able to get this rifle blooded this fall.
 
Paul
Be nicer than necessary.

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