# of Shots per Group and MOA - Results

[Bob Wright]

Very interesting report! I need to work harder at being more honest with myself about what me and that particular rifle can repeatedly do. I think the end result is it will force me to try even harder in every aspect of reloading and shooting for my hunting.

 

[HRM Johnny]

Speedengineer,
Great post. I appreciate all the work that went into it. Thank you very much.
Johnny

 

[SO92]

@speedengineer

Thank you for your time and efforts on this project. I appreciated the insights as well as the discussion it generated.

 

[User4302021]

This is why I verify a winning combo at 200yds w/20 shots (4 groups of 5 shots at same POA).

 

[Ranchdog]

Well this sure makes me feel inadequate in the realm of shooting. Thank you for the paradigm shift in grouping size to test group number process for hunting rifles.

 

[speedengineer]

.25 all day, (as long as you do your part!)

Seriously though, this has to be one of the best posts I have ever read on this forum. Unfortunately, despite its clarity and simplicity, we still get people coming up with lame excuses as to why they choose to define their rifle's accuracy using low-shot-count groups.

Mr SpeedEngineer Sir, a challenge, should you choose to accept it! Would you turn your brilliant analytical mind to the practice of one-shot-per-charge-weight ladder tests? I fear another sacred cow might be facing the captive bolt gun....

Yeah...I've never done a ladder test, mostly because I don't want to waste the time and ammunition. I think many people have tackled this topic already. The idea of looking for a velocity plateau of a few fps (using a 1-shot ladder test) when your standard deviation of velocity is of similar or larger magnitude is silly.

I'm not interested in doing a full statistical analysis, but this graph took only a couple minutes in excel. It just applies some random velocity variation to a nominal velocity vs charge weight profile (linear) by using a normal distribution with a specified standard deviation. The point is just to visually indicate how much noise one would expect to see in any given 1-shot per charge ladder test. It's repeated 5 times, a through e.

^ Line "e" looks like a real swet spot around 57gn! ...Oh wait, that's just noise.

I'd guess that one would probably need to have an SD of around 2 fps or less for this type of test to have any reliability.

I once searched the internet really hard to find someone who had performed a 1-shot ladder test twice in a row, to see if they got a similar result the second time as they did the first. I wasn't able to find anyone who had shared such info. And, I bet even if someone out there did get two tests in a row to agree on a plateau, a third test likely would not!

 

[Tiny Tim]

I once searched the internet really hard to find someone who had performed a 1-shot ladder test twice in a row, to see if they got a similar result the second time as they did the first. I wasn't able to find anyone who had shared such info. And, I bet even if someone out there did get two tests in a row to agree on a plateau, a third test likely would not!

I seem to remember reading someone doing something similar. May have been 3 targets, shot round robin. Three cartridges at each powder charge. He never went to the depth of analysis you are. I really don't remember much about it. Had muzzle velocities recorded for each. It may have been an OCW test. Sorry, dont remember the details.

 

[LongBomber]

The thing with a satterlee velocity test is you actually should shoot the string 5-6 times and end up exactly with your first chart. Where the lines of multiple strings converge would be your node. An example would be around 56.5-56.6 in your first graph. And several clear examples are in each chart. Then you need to hope one lines up with your barrel time, if you are a believer in that.

I have shot multiple paper ladders which do line up with each other, but that is back to shooting at something over 600y and looking for vertical only. I doubt that many do the ladder test in that way since the magnetospeed and labradar came out. Much easier to just look at speeds and guess. Out of something over 50 ladder tests tracking the speed, I don't think any have lined up perfectly.

Yeah...I've never done a ladder test, mostly because I don't want to waste the time and ammunition. I think many people have tackled this topic already. The idea of looking for a velocity plateau of a few fps (using a 1-shot ladder test) when your standard deviation of velocity is of similar or larger magnitude is silly.

I'm not interested in doing a full statistical analysis, but this graph took only a couple minutes in excel. It just applies some random velocity variation to a nominal velocity vs charge weight profile (linear) by using a normal distribution with a specified standard deviation. The point is just to visually indicate how much noise one would expect to see in any given 1-shot per charge ladder test. It's repeated 5 times, a through e.

View attachment 203617
^ Line "e" looks like a real swet spot around 57gn! ...Oh wait, that's just noise.

View attachment 203618

I'd guess that one would probably need to have an SD of around 2 fps or less for this type of test to have any reliability.

I once searched the internet really hard to find someone who had performed a 1-shot ladder test twice in a row, to see if they got a similar result the second time as they did the first. I wasn't able to find anyone who had shared such info. And, I bet even if someone out there did get two tests in a row to agree on a plateau, a third test likely would not!

 

[ilc]

Where the lines of multiple strings converge would be your node. An example would be around 56.5-56.6 in your first graph. And several clear examples are in each chart.

I think you've nailed it. Random numbers generated by a computer can convince people that they have discovered a magic load.

Guns are just random number generators.

 

[L.Sherm]

Somebody explain to me what " minute of game is"

 

[Mikecr]

to say aggregates don't matter is really saying you are ignorant of probability and statistics.

It's contempt I guess, as I believe averages(plain or fancy) will not influence hunting shooting capabilities.
I don't 'shoot at' game. I 'shoot game'. And I wouldn't accept a caused percentage of misses for graphs.

For a bit I had a Tubb2000 new from the factory & worked up a load as standard for best hot grouping.
In good conditions It was reliable for true 1/4moa 5shot groupings @ 600yds -with a fresh foul & sighter warmed (IBS format). That seemed promising, but I had actually bought the gun for varmint hunting.

So then I ran a test I do with every gun I intend to hunt with. I shoot a 10min shot rate, because every gun I've tested hates a 10min shot rate. I shoot 200yds, because that happens to be my worst distance and it's far enough for this.
I shoot 1 cold with immediate followup, 10mins later I do it again,, repeating.
A good hunting gun and load will hit a 1" dot at this range, shooting with this crummy scenario, any day, off a field rest. A bad hunting gun can't do it, regardless of load, and regardless of it's hot grouping capability.
While I had not yet worked up a cold bore hunting load for it, I could tell right off the bat by this pictured result -the gun had no varmint hunting potential:

I never shot the gun again. Just sat it in the safe for a few years and then sold it for a pretty good profit.
It was 'competitive' (per it's design, probably still is). But that's all.
I could have stretched the shot interval and put a huge effort(months) into better cold bore results with this gun, but I didn't feel good enough about that test result to pursue it.
Looking back, I know I made the right decision there, because that's just really bad...

This doesn't seem a success story I'm sure but most hunting guns are not really.
Not when you cast aside your wallet groupings, and objectively test and accept what you're dealt for real world HUNTING ACCURACY capabilities.
The reason I bring this long story up is that I just don't see how statistics could change the outcome.

 

[User4302021]

Where the lines of multiple strings converge would be your node. An example would be around 56.5-56.6 in your first graph. And several clear examples are in each chart.

There is nothing at 56.5 in that chart.

If you notice, all the converging lines that look like "flat spots" are in between increments. It is simply the lines crossing one another from one increment to another. There is no actual data there.

If you actually shot a number of shots at those increments, then they too would be as scattered as the rest.

 

[LongBomber]

You are right there is no data at 56.5, going with the steps in the graph you are infering and building a range where the es/sd numbers are the tightest, not going for a flat spot in velocity. Really you have convergance from 56.4-56.6 and again up higher. That convergance is a reduction of es, and when you shoot more it typically does hold up.

There is nothing at 56.5 in that chart.

If you notice, all the converging lines that look like "flat spots" are in between increments. It is simply the lines crossing one another from one increment to another. There is no actual data there.

If you actually shot a number of shots at those increments, then they too would be as scattered as the rest.

 

[jasonco]

Good stuff here!