Math Quiz...

[JustMe2]

Load #1. I feel the "mode" is more important than ES and SD. The mode = most. Where did most of the bullets impact? You can always expect a flier which will change your ES or SD. Also verticle spread is more important than horizontal spread because environmental factors have more of an affect on the horizontal spread than the verticle spread, like wind, trigger pull, mirage, breathing, shoulder fit/recoil angle, scope level, forearm pressure, etc. Some of these also affect verticle but they generally have a greater affect on horizontal. This is why the winner of a competition has the most Xs or 10s, not the one with the smallest ES and basically what med358 explained.

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[Pudgy]

Which load would be more accurate @ 750 yards?
(I don't know the answer, not going to mention rifle or load info.)

Bullet DiA. = 0.264", ~124/125 grain
Est. B.C. = G1 - 0.600 / G7 - 0.298

#1. 3/8 MOA at 100 yards with an extreme spread of 32fps, muzzle velocity of 2,904fps
or
#2. 7/8 MOA at 100 yards with an extreme spread of 8fps, muzzle velocity of 2,841fps

I'm sure this will be easy for some… I'm scratching my head after a day at the range. I'm wondering how much the ES could play on accuracy at this distance (10" steel plate).

Load one by a long shot

I shoot F-class and have had 20 shot strings with an ES of 25 and scored 200 - 13 x

At the recent SWN Palma (800-900-1,000 yds) 29 out of 45 shots were sub 1/2 MOA
With a load that in practice had an ES of 20.

The point is the majority of my shots were sub 1/2 MOA. If I had started with a 7/8 MOA gun, I would have no chance at all to shoot that good.

Remember ES is the Extreme spread- that is some are 15 FPS faster and some 15 FPS slower and most are somewhere between.

Can you shoot good enough to notice 15 fps change?

While an ES of 30 isn't ideal, it's way better than an almost 1 MOA gun to start, before adding all the human and environmental factors.

 

[huntinghuasna]

I appreciate all the feedback, some interesting (helpful) concepts. I'm definitely gonna do a little more playing around to ensure my numbers are solid then take this rifle out to 600 yards and start grouping cold bore shots to settle it.

 

[Taylorbok]

@RegionRat has got the correct answer, in this case the smaller group with the larger ES is still the better option. The way to figure it out is use your calculator and enter the max and min numbers from your ES and the difference in the elevation correction is how much you are potentially adding to group size due to ES

 

[MSURunner]

Not knowing the sample size for both the group size and velocity readings hurts being able to make an accurate assessment, but this website does a good job of running those simulations to let you know what you're chasing. What you will need is a decent SD, not ES for your shots. ES doesn't tell us much about the collective dataset, just the extremes.

Bison Ballistics

If you really wanted get a better idea, run through the simulation multiple times with multiple conditions present to give yourself a better idea of what it is doing. As others have said, I would stretch it out a bit further and shoot a 5+ shot group to see how it performs as that larger group size doesn't seem indicative of the tighter ES.

 

[lancetkenyon]

Give me load #1 all day long.

These numbers are close, based off a 140 Hyb that I have several loads in my Shooter app. But BC is G7 .317, so close enough for a comparison. Numbers across the board might increase 2-3%.

Load #2 starts out with too many deficiencies.
More than double the group size to start. 7/8MOA @ 750 yards is a 6.5" group size at 750 compared to 2.8" for load #1. 3 3/4" more with no other errors.
TOF is close enough. .900 vs .919. Not a lot of time for wind to effect bullet flight.
32fps ES allows for around 3.1" difference in vertical, so allow for 1.5"+/1 from POA. And that is at max ES between slow and fastest. Anywhere in between cuts that drop variation. 8fps allows for .8" difference. So allow .4" +/- for error to POA.

Also, unless you have 20-50 rounds for ES verification, take those ES numbers with a grain of salt. That 8 could easily be a 30+ ES, and the 32 could be a 60.

Increasing round count, the ES will never go DOWN. But I bet they go up.

 

[floyd kittrell]

When in doubt, shoot it 750Y; you need to figure out your dope anyway.

X's 2

 

[FireFlyFishing]

How many shots/group for your data?

What were your SDs?

If it were me I would work on group two and play with different seating depths. You may get your numbers and groups on paper to beat group1.

 

[huntinghuasna]

How many shots/group for your data?

What were your SDs?

If it were me I would work on group two and play with different seating depths. You may get your numbers and groups on paper to beat group1.

Very small sample, two three shot groups ea... Not sure of SD's, gonna have to see if I can pull from new Garmin Xero. This is a hunting rifle and I'm trying to limit components spent on load development, using McGuire Ballistic 125g Copper Rose over 38.5 - 39.5g Varget. Planning on trying to tune load #2 with COAL then taking both loads to 600 yards for the real deal, cold bore groups. This is going to take a few trips to the range. The 3/8 MOA is suprising to me, need to prove this is repeatable, not even sure if I'm a 3/8 MOA shooter with this rifle (or any rifle).

 

[MSURunner]

Very small sample, two three shot groups ea... Not sure of SD's, gonna have to see if I can pull from new Garmin Xero. This is a hunting rifle and I'm trying to limit components spent on load development, using McGuire Ballistic 125g Copper Rose over 38.5 - 39.5g Varget. Planning on trying to tune load #2 with COAL then taking both loads to 600 yards for the real deal, cold bore groups. Going to take a few trips to the range.

Garmin should show the SD on there. If not, pull the shot strings individual velocities and put them into a dozen plus different SD calculators online. I would also echo the proof in the pudding regarding which would shoot better at range. I know it sucks blowing through components, but you'll need a larger sample size to have good usable data at 600+ anyways. If I were trying to save the components usage and was torn between those two, I would probably load up a 3-5 shot group on both and shoot them at 300, then pick the winner and shoot it at 600 to confirm. Then you should have another 6-10 shots worth of velocity to start getting a better idea of SD for the winning load. That is still not a great sample size, but it's a helluva lot better than 3 and you'll have some data that you can use to help determine what the BC is for that bullet in your rifle.

 

[Frank in the Laurels]

..nonsense, the only thing that can even remotely answer that question is a sheet of paper....I've seen countless educated guesses go down the toilet with a single sheet of freezer paper...

 

[med358-boise]

The purposes of mathematics is not a number, it is a decision.

In this case, the math in my view is close but not conclusive because of too many variables and too many things having to be held constant which is inconsistent with real world practical applications; so therefore, the decision is further testing via actual shooting is required.

 

[heat_and_fam]

Which load would be more accurate @ 750 yards?
(I don't know the answer, not going to mention rifle or load info.)

Bullet DiA. = 0.264", ~124/125 grain
Est. B.C. = G1 - 0.600 / G7 - 0.298

#1. 3/8 MOA at 100 yards with an extreme spread of 32fps, muzzle velocity of 2,904fps
or
#2. 7/8 MOA at 100 yards with an extreme spread of 8fps, muzzle velocity of 2,841fps

I'm sure this will be easy for some… I'm scratching my head after a day at the range. I'm wondering how much the ES could play on accuracy at this distance (10" steel plate).

Are those group sizes over 3 shots or 20?

 

[bultinkle]

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