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ES/SD, Primers, Neck Tension, Give me your input!

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ES/SD, Primers, Neck Tension, Give me your input!
« on: February 20, 2018, 06:58:14 PM »


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I'll preface this with me just getting into reloading. I've always bought match ammo but built a custom rifle for this season and wanted to really feed it something it deserves. I spent a bunch getting all of the equipment that I always heard people say "I wish I had that..." "Oh man that would be so nice to have..." etc... Anything that made them better or made it easier on me I was down for.

Anyway, I got a good load worked up and just wasnt happy with the SD and ES. It shot well under 1/2 MOA at 600, but I know they could be better.

I went to the range tonight after making a primer change. (I wanted to make one change at a time to see what affected what and know what part was actually making a difference)

Over 20rounds I had an SD of 7.6 (with the federal primers vs the CCIs) And other than 4 oddly high shots (random and not in an increasing heat order) had a 15fps ES.

What is everyone getting, checking, tweaking, to improve their SDs?

« Last Edit: February 21, 2018, 03:03:09 PM by gconnoyer »

Re: ES/SD, Primers, Neck Tension, Give me your input!
« Reply #1 on: February 24, 2018, 01:02:50 AM »

Jeff M

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If the bullet goes where I aim it, that's all I care about.

Personally, I think too many guys, especially new guys, get caught up in chasing numbers.  If they were to simply load their ammo without all the additional nonsense, and then spend that time savings on the range burning said ammo, they'd be in much better shape come match day.

You telling your squad "I have an SD in the single digits!" doesn't win you the match.  Impacts do.

Unless, that is, you're talking about benchrest or something.  But then I suspect you would still be on the reloading bench because that 1/2 MOA group would be making you ill.  LOL

As far as neck tension, I do know that number on my ammo.    .002"  Why?  Because that's what I read on the internet.  Honestly.  It has worked for me so far, so I see no reason to change it.
Every time you make a typo, the errorists win.

Re: ES/SD, Primers, Neck Tension, Give me your input!
« Reply #2 on: October 05, 2018, 06:16:23 PM »


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Okay, this thread has some age on it, but I'm trying a new place to participate in topics that I see here without the drama & dick swinging that I see elsewhere...

To the topic, I've never quite been able to calculate why there is so much emphasis placed on SD. For me, ES seems to be adequate. If I know the range of velocities over a reasonable representation, I can effectively predict a POI at given range - within an equally reasonable impact 'range'. Now, not being an acedemic or statistical analyst, maybe I'm missing something regarding the significance of SD over ES...

I use a chronograph for two things: 1) to assist in determining a stable, repeatable load, and 2) to provide a starting point for a ballistic solver.

Stable loads, at least in my experience, tend to level out (in terms of velocity) over a small range of powder charges, indicating a 'node'. Even when I have trouble interpreting what a ladder test or a group test of same charge has printed on paper, the velocity readings can assist in interpretation. I've always found that anytime I've been under 20 fps ES, I have a well behaved load. And this is WAY out of what many PR guys claim to be "acceptable".

As for the use of velocity for ballistic solvers, I've never seen an accurate solution derived from a measured average from a chronograph alone. It ALWAYS requires field verification. Always.

Knowing your speed & ballistic coefficient is all neat 'n stuff, but unless you go out and verify & record results at various ranges in various conditions, it's all just theoretical reference material. The target doesn't lie. But the target will tell different stories on different days. Hard data is the only data you can rely on.