Lowering ES and SD

rockytop65

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Sep 1, 2019
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Ms
Wondering if someone might could help me with bringing my ES an SD down on my 300rum. I’m fairly new to reloading an have done all I know to do. My col is as far as I can go an still get in the mag. I’m using H1000 an fed. 215m primers, have also tried cci primers. My ES is 26 and my SD is 12.
 

Jud96

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Jun 30, 2013
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Tip Top of West Virginia
That’s really not a terrible ES and SD to start with. I’ve found best results by finding a flat spot or “node” in my powder charge. I start a few grains below book max and work up one round at a time in .2 or .3 grain increments shooting each shot over the chronograph until I see pressure signs. Then I look over my data and there will be a window in your charges where loads that are .5gr or more different will have velocity numbers within a few FPS of one another. Then I load in the middle of those charge weights and go test 5-10 shots over the chronograph with that load and if the ES is under 20 I call it good.
 

YZ-80

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Feb 20, 2019
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665
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Maryland
Wondering if someone might could help me with bringing my ES an SD down on my 300rum. I’m fairly new to reloading an have done all I know to do. My col is as far as I can go an still get in the mag. I’m using H1000 an fed. 215m primers, have also tried cci primers. My ES is 26 and my SD is 12.
Well, don’t beat yourself up. These numbers are pretty decent, in fact I’ve read that if you can keep ES under 20, you are in pretty good shape. I watch for vertical dispersion at 300 yards and I’m under 1/2 minute. I’m seeing ES of around 30. For my needs that is more than sufficient but I know there is room for improvement. Anyway, I was watching a YouTube video the other day and a guy was testing all kinds of factory .308 ammo (Federal
GMM, Hornady, etc). I was quite surprised to hear him report spreads with some of these factory brands of 70 to 90 FPS. Now I don’t feel so bad about my spreads but I still wanna get them down. Controlling neck tension seems to be a significant factor but I think I need to experiment with some different primers too. Just my .02.
 

rockytop65

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Joined
Sep 1, 2019
Messages
13
Location
Ms
What’s your full dataset look like, and how far are you shooting?
I mostly shoot 300yrds at my house an have shot some out to 800yrds. Just joined a club that has a 1000 yrd range. That’s why I want a little better. I’m using 87grs h1000 with 210 Berger vld. Been up an down with powder, using rem. Brass also tryed federal brass
 

rockytop65

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Sep 1, 2019
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Ms
Thanks guys for the tips I’ll do a little more testing. Like putting lead down range
 

johnnyk

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Dec 24, 2001
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2,160
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Potters Hill, NC
I'm no expert on the subject but a couple of things I have noticed is neck tension and bullet design. I think seating depths and pressure(s) also play a role but don't know enough yet.

Specific neck tension is a new "learning curve" for me. All I ever really knew was that it needed to be consistent throughout the lot of brass I was using and that was controlled by regular annealings and sorting your brass. With consumer annealing machines becoming more affordable & available, hopefully the science will soon be common knowledge. You can find your rifles preferred tension by using bushing dies and purchasing different internal diameter bushings. If you got multiple rifles/cartridges it can get expensive.
By sorting brass I mean keeping it separated by the number of times it's been shot and by head-stamp, if you use different mfg's. The work hardened condition determines its softness or brittleness.

Bullet design: I've noticed a trend in about three of my rifles. In my .300WinMag (Pac-Nor), I can shoot Berger 215gn Hybrids and 212gn ELD-X's with the same load data and the ELD-X's slightly beat out of the Bergers in accuracy, velocity and ES/SD's! It's not much but I see it on the LabRadar and on paper. I first noticed this when shooting 140gn VLD's and A-max's in my 6.5-284Norma (Lothar Walther). Again, recently in my 6mmBR (Shilen), the 108gn ELD-M's are just a tad tighter and consistent than Bergers of similar weights. I don't know why. Truthfully, I really want the Bergers to shoot but I can't kick the Hornady's to the curve, especially if I feel they'll give me a edge at LR, PLUS they're CHEAPER!
 

Mram10us

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Oct 19, 2019
Messages
2,574
Location
Idaho
Do a test with annealed and neck turned brass with the usual case prep and see if it helps you. I noticed a difference in accuracy with my edges and rums, but did not check sd and es. Simple on paper data. The guys above have everything covered.
 

dougduey

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Joined
Apr 11, 2011
Messages
751
Location
San Antonio, TX
I went down this rabbit hole not to long ago. Hers what I learned, and it was stated earlier. Consistent neck tension and powder charge are what’s needed. I use the Sinclair Neck Turn mandrels to set a perfect neck tension just before I start drooling powder. I also get my powder charge to the kernel of powder. I haven’t bought the A&D. FX120i scale and auto trickled yet (which can accurately get a charge to the 0.001 gr weight) so I have to do it with a pair of tweezers. I hit May target charge (on my Chargemaster) then remove powder a kernel at a time until it weighs 0.01 gr less. Then I drop one kernel back in the pan to get it back to my target charge weight. It’s time consuming but it works. Got an ES of 2 and SD of 0.0 the other day in my 280 AI with this method.
 

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