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Load development struggles

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WVshooter

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Jan 21, 2012
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NC
#1
I’ve been working up this load for 300 Norma, AXSR rifle, 27” Bartlein barrel, first time with a magnum, and reached a point where I’m looking for suggestions.
Started with new Lapua brass sized for .002 neck tension, 230 A-Tips .050 from lands, 9 1/2M primers and H-1000.

I did a powder charge test from 82.1-85.1 in .6 gr increments OCW style, ascending order, 3 rounds each total. Stopped at 84.5 because it was flattening the primers pretty hard by then. Went from about 2900 fps up to 2980 fps. Best groups and ES were at 82.1 and 84.5.

I loaded up five rounds each of 82.1 at .030, .050 and .070 from the lands and fired them in the same ascending order style and got these results.
IMG_9456.jpeg


Loaded up 10 rounds at 82.1/.070 to see if I could confirm it and it looked like this.
IMG_9457.jpeg

Decided to test the same load again to see if this was me and to check neck tension results so I loaded up ten each at .002 and .003 neck tension and got these results. ES at .002 was 21 and at .003 was 49.
IMG_9458.jpeg

I shot every test at the same range, same time of day, nearly identical conditions prone on a bipod with a rear bag. My 215 Berger load I did is pretty consistently .5 MOA but this 230 load after that one outlier seating depth group is closer to 1 MOA.

Looking for some outside input. Time to change powders? Drop the charge a little?
Repeat a previous test?
What say y’all?
 
#2
That’s A LOT of shooting for a 300NM for both the barrel and for you, especially if it’s your “first time with a magnum.

So, some of that looks like shooter fatigue to me. The .070” off group at 82.1 looks good and shows what the gun is capable of (albeit a small sample so we’d expect that group to grow if you shot 20 rounds.). If it was me, I’d stop right there. Come back, if you want to verify, and shoot a three shot group at some later date when you are warmed up but haven’t shot much.
 
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#3
OP, I hate to say it, but it looks like you got bit by the sample size bug. The good thing is that you repeated the test, instead of going off of one group and calling it good (BTDT and learned my lesson many years ago).

I've got about a dozen barrels I load for as a hobby (or insanity). I have some that are temperamental with certain bullets and stupid easy with others...seems like yours is an example of this. I also have barrels with wide, forgiving nodes...and some that you have to stay on top of.

I'm a fan of the idea that you go back to the 215gr Bergers if they're consistently half-minute. Nothing makes shooting less enjoyable in a hurry than chasing accuracy. If you are after a better BC than the 215s, then just move up in the Berger line.
 
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#8
I shoot 230gr Bergers in 300PRC, 245 Bergers in 300NM, and 300 Bergers in 338NM. All from the same WinTac-chambered, factory AI AXMC/AXSR, 27” barrels as yours. They all seem to like somewhere around.030” jump. While it should work OK, I think H-1000 is a bit fast for Normas with heavier bullets. I’d switch to Berger first, then if that doesn’t do it, go to Retumbo or N568. N570 is “the bomb” for 300NM and 245s, but I’m not willing to give up even more of the the already short barrel life of the 300NM to such a barrel-burning powder.

Also, and I hate to say it, but “first time with a magnum” is ringing MY clue phone. The disparity in groups looks a LOT like what happens with inconsistent recoil management. Be honest with yourself. Do you know exactly where your reticle goes throughout the entire recoil pulse? Is it tracking straight back and returning to the aimpoint? If not, find a mild/decent load and forget about load development until you’re satisfied with your recoil management, then proceed. You only have “so-many” rounds to shoot on a 300NM barrel.
 
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#10
vh20 said:
I shoot 230gr Bergers in 300PRC, 245 Bergers in 300NM, and 300 Bergers in 338NM. All from the same WinTac-chambered, factory AI AXMC/AXSR, 27” barrels as yours. They all seem to like somewhere around.030” jump. While it should work OK, I think H-1000 is a bit fast for Normas with heavier bullets. I’d switch to Berger first, then if that doesn’t do it, go to Retumbo or N568. N570 is “the bomb” for 300NM and 245s, but I’m not willing to give up even more of the the already short barrel life of the 300NM to such a barrel-burning powder.

Also, and I hate to say it, but “first time with a magnum” is ringing MY clue phone. The disparity in groups looks a LOT like what happens with inconsistent recoil management. Be honest with yourself. Do you know exactly where your reticle goes throughout the entire recoil pulse? Is it tracking straight back and returning to the aimpoint? If not, find a mild/decent load and forget about load development until you’re satisfied with your recoil management, then proceed. You only have “so-many” rounds to shoot on a 300NM barrel.
Click to expand...
First time doing load development with a magnum. I’m not an expert but I shoot a lot, dry fire a lot and yes my reticle tracks and returns to the target and I’m generally able to call my shots when I make mistakes. All my shooting is with an Ultra 338 can on the gun too and I don’t find the recoil to be all that bad.
 
#11
WVshooter said:
First time doing load development with a magnum. I’m not an expert but I shoot a lot, dry fire a lot and yes my reticle tracks and returns to the target and I’m generally able to call my shots when I make mistakes. All my shooting is with an Ultra 338 can on the gun too and I don’t find the recoil to be all that bad.
Click to expand...
Just saying...I started shooting 338LM 13 years ago with brakes, and since 2017 with TBAC 338 Ultras, adding 338NM, 300NM, and 300PRC rifles along the way. I shoot 2-3x/week. There are still days I struggle with it and know I am not on my "A-Game" with recoil management.

I don't flinch, and don't think I "pull" shots very often. But if you don't manage that recoil properly, it will bite you. Dry firing will not help with this. Most of the time I'm satisfied. But when I do notice a problem, it's usually the reticle going off to the left of the aimpoint during the pulse (right-handed shooter). Also sometimes it may go up - usually a sign of putting too much pressure on the cheek weld. Almost never do I see it go down, or right.

Anyway, the my main point is to be self-critical of your recoil management, notice what it's doing, and whether or not it might have an effect on your groups.
 
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#12
I shoot a 7-300 PRC. It is definitely harder to concentrate on shooting well than any one of my 6 or 6.5mms. 3,900+ foot pounds of energy does that to me, even more so when I developed a load for my buddy's 300NM at around 4,200 ft/lbs.

I had to keep the shot strings to less than 10 before I started to degrade my fundamentals. I guess that makes me a bitch. Surprisingly his 300NM loved 215 Bergers over 82gr H1000. Stupid accurate (in the .4s).

As the OP apparently has a half-minute load with the 215s as well, I'll trust his self-assessment that he can handle the big magnums well enough to tell a difference.
 
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