Thread: .243 load development part deux

Originally Posted by whanahuia

If the load hasn't grouped 3 shots to a standard you are happy with, firing two more isn't going to improve it. It can at best stay the same.

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Pretty much this. 3, 5 or really even 10 can't show you how big the extreme spread of the group (group size) is going to be but it can tell you that it will ATLEAST that size so if its worse than what you want a 30 round group to look like at 3 shots adding more data is irrelevant as i dont care HOW bad it it just that its bad at that stage. It doesn't give any hard data on what teh final result will be.

It's not contrary as there are 2 seperate statements. Low samples sizes cant prove how precise a load is. And a low sample size can show how precise a load could be best case. It takes alot of shots to get an accurate measure of precision (mean radius stabalises around 30 and is a better metric @gimp has done lots of posts on how to get this. There are a few apps but I digress. It is true in the case it can prove that a load won't ever be better as its already shown it can be atleast that bad. But it one 5 shot group is under the precision required more data is required to confirm it will remain under with time but if its already too bad then no amount of shots will make it smaller ie a 2.5 inch 3 shot group at best will be a 2.5 inch 30 shots group. But a 0.1 inch 3 shots group could also end up a 2.5 inch 30 shot group. The more shots the more likely it will and the smaller the likely deviation.

I generally work on as soon as a shots thrown outside 2 inchs I stop testing the load because im looking for a bear minimum of 1.75inchs at 100 for 30 rounds. But obviously ideally want something better. In field conditions the hit probability difference between a 0.5 and 1.5moa system with an average wind caller is very minuscule as other factors come into play.

So in the above image portraying a 30 shot group. If you at random picked any 3 shots it could give wildly different results. Maybe you shoot the 3 worst in that group maybe you shoot the 3 touching but most likely you shoot something in the middle.but there's a huge range of possible outcomes.

Below an average expected increase in groups size vs shots fired. You will see that even 50 shots groups expect to increase 7% from the average 30 and vary 10% between 50 shots groups. This is because the group size only factors in 2 shots. Mean radius becomes consistent much faster and id pretty steady around 30 shots.

Originally Posted by Stocky

Attachment 279105

So in the above image portraying a 30 shot group. If you at random picked any 3 shots it could give wildly different results. Maybe you shoot the 3 worst in that group maybe you shoot the 3 touching but most likely you shoot something in the middle.but there's a huge range of possible outcomes.

Below an average expected increase in groups size vs shots fired. You will see that even 50 shots groups expect to increase 7% from the average 30 and vary 10% between 50 shots groups. This is because the group size only factors in 2 shots. Mean radius becomes consistent much faster and id pretty steady around 30 shots.

Attachment 279106

Thanks for explaining that, that makes sense

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Originally Posted by Zedrex

Watched and most of his commentary is around his view on barrel tuners and why he doesn't use them, he also touches on other variables (temperature) that, if I'm understanding him correctly make barrel tuners like everything else inconsistent in their effect on accuracy and I am aware that there are many enviromental variables that will impact grouping

My understanding of your comment in response to "There is plenty of evidence out there where shooters have experienced groups converging and diverging as they move up through load weights in as little as 0.2gr increments with a variance of sub MOA to 1.5MOA over 3 load increments.- Feel free to provide that data and shut us up, or drink."

Is that you were dismissing varying load to tune harmonics was a load of old bs and in both of Marks video's he alludes to charge weight, seat depth as being methods to tune a load and barrel harmonics in order to try and have the projectile exit the muzzle during the barrels "dead" moment which reinforces my thought that charge weight MUST have an influence on grouping.....BUT I also think that what you were maybe trying to say is that harmonics are not going to have a marked effect on grouping at the distance I was shooting the test loads...and that's a possibility BUT it's also possible that it may have an effect AND it MAY be that that effect is negligible. I think I asked IF harmonics could have an impact and when questioned I replied with the "plenty of evidence out there" which there is but I didn't have the context of "over what distance" Marks video mentions a 1/4" difference but again no context of over what distance...so it's back to insufficient data

I don't really consider Mark to be an expert tbh but you brought him up. The video I linked to is his take on barrel tuners, yes, but in it Mark brings up that charge weight, seating depth, barrel length, and temperature as also being things that tie into harmonics - all playing together with the aim of timing bullet exit with when the muzzle is resting. His main gripe with tuners is that temperature (of the barrel steel) is one that you cannot control and the effect it has means tuners cannot work as claimed, as the goalposts are moving too much.

Temperature also affects the powder (as none of them are perfectly temperature insensitive) so its impact can be twofold. If Mark's argument is that barrel tuners are snake oil because the effect that a small change in temp defeats whatever it is that they are claimed to be doing... does it not also stand to reason that the effect of tweaking charge weight or seating depth to try and control harmonics would also be undone by a change in temperature?

So my position is either that: the effect of harmonics is real but nothing you do can realistically control them - so you may as well not bother trying. Or the effect of harmonics is negligible - so you definitely should not bother trying. Whatever it is, I don't think you'll see a significant difference between 42gr vs anything else, once you do some large sample size testing.

But who the fuck am I and what the fuck do I know? If the results you've gotten so far and the research that you've done lead you to believe that you could well be onto a magic harmonic sweet spot that you can exploit - just by using 42gr of powder - in your 243 hunting rifle to get it to go from shooting dinner plates to golf balls... Well I've told you what I suspect you'll find... But, this is not a hill I care to die on. If you are not convinced, fine. I'm really not interested in getting any further into the weeds over it with you, let alone having a lively debate or "robust discussion".

Once you go shoot some statistically significant groups at 41.5gr, 42gr and 42.5gr, you'll have your answer.

I don't watch videos from that chap Mark but from what I've seen, he doesn't have a firm understanding of the theoretical principles behind rifle precision, and doesn't question or test the conventional wisdom.

This chap here believes in Nodes, and believes in tuning seating depth etc. This test he does demonstrates wonderfully that although he believes in them, he cannot actually find any evidence, with large sample testing. At the end, he has not updated his belief system to match the evidence. It's quite interesting

https://youtu.be/_h4iAiGYbwg?si=6eeh0-JX7HzVFpdg

The harmonics thing...... Why the rail guns,super heavy barrel jobbies are supposedly so good. They are soo stiff there is next to no wobble in barrel at all when shot is fired. They can absorb,distribute heat much better too as have larger surface area. But few folks like carting truck axel size barrels around for hunting...some do,but not many.

It could also be the weight means there is little movement of rifle full stop too. Heavy rifles much easier to shoot well than light ones....

You have to remember that exceptional results are possible with very light high-quality barrels. If you're looking to shave that last 0.1moa to win a bench rest match, yeah, you'll see it

Thanks for sharing your journey into reloading, there are indeed people like Basenjiboy who are generous with their knowledge. What made you decide on 95gr SST's ? Did you make the decision based on your rifle twist rate, in which case could you say more about that, and if you dont mind more detail about your rifle.

He chose the 95grn set cause that's what's in deer season he likes. Rifle is described some posts back....franchi

The more I see too, the more I get frustrated at what the "commercial" focus on hunting rifles has lead us to deem important.

What accuracy do we really need? Probably 2moa. Yet everyone seems concerned about harmonics and nodes etc that are going to improve accuracy by what? Somehow its become important to have a rifle that will shoot well enough to kill at 600 meters, when by the time the projectile gets there it won't be the rifles accuracy that's the most important aspect, but rather the shooters ability to read the wind.

Im just as prone. Im not happy these days unless I can shoot some tiny group each and every time I go out. But the reality is I spent much of the last 10 years hunting wth a "problem" barrel that probably, if put through the tests Gimp suggests, would be terrible on mean radius at around 4moa. But it never cost me a single animal.

My only question is did you try 95gr BT's......

Originally Posted by Stocky

Attachment 279105

So in the above image portraying a 30 shot group. If you at random picked any 3 shots it could give wildly different results. Maybe you shoot the 3 worst in that group maybe you shoot the 3 touching but most likely you shoot something in the middle.but there's a huge range of possible outcomes.

Below an average expected increase in groups size vs shots fired. You will see that even 50 shots groups expect to increase 7% from the average 30 and vary 10% between 50 shots groups. This is because the group size only factors in 2 shots. Mean radius becomes consistent much faster and id pretty steady around 30 shots.

Attachment 279106

The important thing with the right-hand side of this table is that the correction factor, e.g. from 3-shot to 5-shot groups is for an AVERAGE group, and you need to shoot 10+ 3-shot groups to obtain a reasonable average

Been an interesting thread. Imo there's a couple of things at play here. Firstly it appears some people don't know the difference between target/range accuracy and hunting accuracy. They are very different things and it appears some think they need a rifle to be able to shoot tiny groups consistently over multilabel shots to shot animals where you only ever fire one or two mostly. So three shots is sufficient into the kill zone at your maximum distance consistently for your ability . Then you know if something goes wrong on your first shot, you are likely to make a hit with your second. Es imo is very important. If you have very low velocity difference, then your loading procedure is working. If you have big velocity differences from even a small group then you need to find out why and change something in your loading technique . Es isn't to show accuracy primarily . There are other things for that. If your load isn't accurate then there's something wrong with the shooter, rifle , load components. Probably in that order. Fixing one or more of those will sort your accuracy.

Nosler manual has bit in it about sighting in for hunting that,although a bit left field makes sense to me. Fire first shot from steady rest as best you can then follow up with two quickly, similar to what might happen on game....as much a test of YOU as the other bits.