ELR and ES errors?

[GasLight]

Hello all,

I don't have much experience, well any really, with ELR shooting, but I did have a question of my own reloading recently and shooting out to 1000. Reading through a lot of the information in the beyond 1000 yards forums lead me to really wonder on this one at these ranges. What are you ELR'ers doing to compensate for ES errors? What is an acceptable ES for shooting at ELR ranges? I have a load that drives tacks at 100 and the ES is still around 20. This would make an 11" difference at 1200 yards.

Thanks for the input!

DD

 

[RobertB]

Re: ELR and ES errors?

Play with everything you can with your load. Seating Depth, primers, matched and sorted brass and bullets. And then go see what it actually does out in the field. Make sure everything is the the same and right for each shot. Parralax, eye relief, grip and trigger and that the gun is level. Start with small things and work up. What is your SD?

 

[GasLight]

Re: ELR and ES errors?

on that load over a 5 shot string the SD is 8. My question though is more relating to ELR... if I can see an 11" difference at 1200, how is that being compensated for at 1500+?

 

[Lindy]

Re: ELR and ES errors?

ES is not a reliable figure of merit. To understand why, read this:

http://riflemansjournal.blogspot.com/2010/07/statistics-for-rifle-shooters.html

 

[GasLight]

Re: ELR and ES errors?

Ok, read through the majority of that, and feel like I get the point you are making, ES is not a reliable statistical indicator. This does not change my question, but perhaps I need to clarify. What are folks shooting ELR doing about the variations in muzzle velocity from round to round, that can potentially make a difference of a hit or miss? We have no way of predicting what round will be slow or fast before we shoot that round over a chronograph. How can you reliably hit a man sized target at 1500 yards, when you have a potential muzzle velocity difference that can well put you off target, not to mention everything else that is going on at that range?

I am just trying to clarify because it seems as though some folks are having very good luck engaging targets at this range, but I have not read anything relating to muzzle velocity variations from round to round.

Thanks

Dave

 

[Lindy]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">but I have not read anything relating to muzzle velocity variations from round to round.</div></div>

Two factors may account for that.

(1) More people post about ELR shooting than are actually doing it.

(2) The ones who are doing it have no method of compensating for that variation - actually, there is none - so they pretend that it doesn't exist.

 

[jrob300]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">but I have not read anything relating to muzzle velocity variations from round to round.</div></div>

Two factors may account for that.

(1) More people post about ELR shooting than are actually doing it.

(2) The ones who are doing it have no method of compensating for that variation - actually, there is none - so they pretend that it doesn't exist.
</div></div>

Velocity + shooter error will determine your vertical. This will also determine your smallest theoretical group.

I personally do not look at ES. I take my most promising loads from development and shoot them at 500 yds. I take the load with the least vertical. Velocity is what it is.

John

 

[groper]

Re: ELR and ES errors?

what can you do to compensate? Well there is only 1 thing you can do... develop a load with the most consistant velocity possible... theres nothing else you can do!

 

[GasLight]

Re: ELR and ES errors?

OK, I wasn't sure there was a way to compensate for this. What is an acceptable muzzle velocity variation for ELR shooting? Are these loads being prepared in similar fashion to benchrest shooting? With my best load having an ES of over 20, this definately concerns me going past 1000 yards. So I thought I would pose the question here for those that are shooting these extreme ranges with success.

 

[Lindy]

Re: ELR and ES errors?

What you might have gotten from the link that I posted is that you don't know what the ES of your load is. You know the range of the rounds which you chronographed.

One thing some people do is to ignore the ES, but instead calculate the maximum velocity variation from one shot to the next.

But there is simply no way to predict what the variation in velocity is from one shot to another.

 

[GasLight]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">What you might have gotten from the link that I posted is that you don't know what the ES of your load is. You know the range of the rounds which you chronographed.

One thing some people do is to ignore the ES, but instead calculate the maximum velocity variation from one shot to the next.

But there is simply no way to predict what the variation in velocity is from one shot to another.
</div></div>

Lindy this is at the heart of my question. What is an acceptable variation? How can you mitigate the effects of this variation well enough to take shots at human sized targets at extreme range?

Is it really just luck when someone is making hits at these ranges? Or are the targets just large enough to absorb this error? Forgive me for the question as I said previously my experience in this area is extrememly limited, and the question was only brought up when I noticed the difference in my little 6.5 at only 1200 yards which is close to the effective supersonic range of this caliber. I can only imagine that the error gets to be a much larger number at ranges talked about in ELR shooting. From what I am reading people are having much success at these ranges, so I am just trying to be educated on how they are dealing with this issue.

Thanks again for the consideration

Dave

 

[ARMECA]

Re: ELR and ES errors?

From my experience, shooting solid banded bullets in place of jacketed tends to decrease the ES & SD...

 

[GasLight]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ARMECA</div><div class="ubbcode-body">From my experience, shooting solid banded bullets in place of jacketed tends to decrease the ES & SD...</div></div>

To what extent? what do you consider acceptable for ELR work?

Thanks

DD

 

[jrob300]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">What do you consider acceptable for ELR work?</div></div>

Dave,

The question you've asked is a little open ended the way it's worded. Each of us probably has differing expectaions and requirements.

The question is, what do YOU want to hit at ELR? That will determine the level of accuracy and precision required.

If you're shooting a 36" plate at 2000 yds, that's one thing, but hitting an 8"x12" plate at the same range is quite another.

For me personally, it's rather vague. I want to hit the smallest thing at the furthest range for the least money.

So, I shoot the most accurate ammo I can make within reason, and shoot it from the rifle I have today. I shoot a 300WM. It's what I have and probably will not be upgraded. I get what I get.

For others, they build extremely expensive (for me, at least) purpose-built rifles and load (as mentioned) solids because they expect the ultimate in accuracy and are willing to pay for it.

So, in my mind, you work backwards. What do you want to hit and how far away. "Mission defines the equipment".

John

 

[GasLight]

Re: ELR and ES errors?

That question was posed directly to ARMECA, and I also feel like I have quantified my accuracy requirement by posing specifying 'a man sized target'.

Your explanation may very well be the answer to my question. If I have an muzzle velocity variation of 11" at 1200 yards with my 6.5, then I better have absolutely everything else figured to dead perfect in order to hit an 12" target at 1200 yards.

Perhaps everyone is working backwards, and only shooting at targets of a size that will allow their muzzle velocity error to be absorbed as long as everything else is perfect? I only asked the question because in all of the reading I have done on ELR, I have not seen mention of a muzzle velocity variation (MVV) error. And I was shocked at how much my personal MVV would induce an error into my POI at only 1000 yards.

I appreciate hearing from you guys that are shooting extreme ranges and how you deal with this issue.

Dave

 

[jrob300]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">I also feel like I have quantified my accuracy requirement by posing specifying 'a man sized target'. </div></div>

Sorry, missed that Dave.

John

 

[jrob300]

Re: ELR and ES errors?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave</div><div class="ubbcode-body">I was shocked at how much my personal MVV would induce an error into my POI at only 1000 yards.</div></div>

The other question is: is this in theory, or do you see it on the target? In other words, have you shot at 1200 yds and seen the 11", or was that calculation?

If you have chrono error, it may make it look worse than it seems, which is why if I have a load that looks promising, I'll go proof it at least 500 yds. to see what the vertical really is on target.

John

 

[GasLight]

Re: ELR and ES errors?

this is based on a ballistic calculator using information gathered over an Oheler 35. It doesn't change my question even if my muzzle velocity variations are in part based on chrono error. Are you arguing that there are people shooting ELR that have ZERO muzzle variation from shot to shot?

When you note your vertical at 500, are you determining how much of this is due to the muzzle velocity variations? Do you then calculate that variation into your solution for ELR ranges?

I am just asking if this is taken into account during computation for a firing solution at distance, say 1500+ yards? Or is it being covered by another method?

The heart of my question as stated before, is it seems to me that there is definately an unquestionable and unpredictable variation in muzzle velocity from shot to shot. When shooting at extreme ranges, this difference can become a great enough value to create a situation where even inspite of everything else in the firing solution being dead nuts perfect, there is potential for a miss strictly based on variance in muzzle velocity. So my question remains.. How is this being compensated for, as in my reading, I don't see it taken into account anywhere. It seems to me that we are all plugging in an Average Velocity into our ballistic calculators and trusting that, which to me at these kinds of distances raises a ton of doubt.

This error does not seem to be linear either, where if I shoot a group at 500 and measure the vertical distribution of the group, I can then speculate that I will see the same linear distribution at distance. So, if I can shoot an MOA group at 500 means little at 1500 due to the exponential error growing due to muzzle velocity variance.

Anyway, maybe I will not get a solid answer to this question. Maybe no one thinks about this, and they are seeing the results anyway. It is just me thinking, and wondering basically why no one else is thinking of this...

DD

 

[Lindy]

Re: ELR and ES errors?

It's not that no one is thinking about it. Everyone who has shot farther than 500 yards <span style="font-style: italic"><span style="font-weight: bold">knows</span></span> that.

The problem is that since the muzzle velocity of a given shot is indeterminate until after the shot is taken, <span style="font-style: italic">there is no way to compensate for the vertical variation of an individual shot.</span>

 

[groper]

Re: ELR and ES errors?

yeah dude, what exactly are you getting at here??? Of course we use an AVERAGE velocity, its the best number we have for MV!!!

You have an oheler 35, great, its one of the best chronies you can buy and should give you very accurate numbers by its design. USE THEM to find a very low ES load. From my understanding, a load with ES under 10fps is what you should be trying to achieve.

You ALSO HAVE a ballistics calculator, great, use it and experiment with your muzzle velocity numbers to see its effect on drops at distance for the load your using. You will soon see at what distance how much vertical can be expected from your ES given by your accurate chrony.

What else do you want? a magic rifle that tells you the exact velocity of your next shot?

 

[CoryT]

Re: ELR and ES errors?

For handloads, pay careful attention to the ladder test and work out the proper charge weight to minimize vertical spread. For a descriptions, see

http://www.6mmbr.com/laddertest.html
and
http://optimalchargeweight.embarqspace.com/#

Part of what appears to be happening with these optimized loads is pressure and velocity variations are reduced. The bullet leaves the muzzle at what is reffered to as an 'accuracy node' in the vibration cycle. It also seems that slower shots leave with the barrel whip at a higher point and faster shots lower.

When a benchrest rifle can produce a 2" vertical spread at 1000 yards, even if it quadrupled rather than doubled you would still have only 8" at 2000.

With an SD of 8, some 98% of all shots will be within 24 fps of average. Many will be within 8 fps of the average, about 60%, and about 20% will be within 16 fps of average. While the actual velocity of a given shot is unknowable in advance, a tight SD load at an accuracy node can produce much better results than may otherwise be expected.

 

[Crosshairs6]

Re: ELR and ES errors?

Correct me if I'm wrong but all you are talking about is internal ballistics for your rifle. It's all about limiting the variables. RobertB mentioned this earlier.
What type bullet and powder combination works best with your rifle? (hence load development)
Are you reloading with the same components? (Brass, primers, powder,etc.)
Bullet seating depth?
Are you leaving your ammunition in the sun on the range?
Any of these issues equate to differences in chamber pressure. Differences in chamber pressure mean different muzzle velocities. Compound any of this with a poor optic, human error, etc. and it will make for a larger shot group especially at extended range. Personally, I believe a ballistic PC will get you so far. It is only a guide. There is no substitute for firing the rifle at your desired maximum range and find out what you and the rifle can do together. That is why I shoot.