Thread: .243 load development part deux

You see what I mean?

Originally Posted by earplay

Reading this thread got me to thinking if there was a way to visually represent some of the primary factors and their order of importance ('effect size') relative to load precision, that might be helpful to newcomers. I'm only a little further up the reloading mountain than the OP by the looks, but I like to read and try and condense information to better understand the overarching principles at play.

I was wondering if the following diagram might help capture some of this...happy to be corrected or have this expanded upon if useful.

Attachment 279017

I personally am a big fan of the word "esoteric"


You need another arrow on the left facing the other way which is for "effect size" (low top high bottom) and then a dashed line between the middle 2 sections labeled "unproven above". I'd also separate charge weight above the line and seating depth (juuuuust) below it.
Otherwise, excellent

Bullet should be on its own, as a major player at level two; and the bottom Firearms factors should be Barrel and Bedding, I reckon

The thing with this is . . . There were a lot of theories out there, developed over the last 100 years or so, primarily round trying to understand and explain various barrel/load harmonics. These are what you read when you do "research". However they are all based on a good deal of "belief", just like those other research books like the Bible and Koran!

Recently Hornardy used fully scientific methods to understand the results of various barrel harmonic/reloading methodologies. What they found is explained in their podcast #50. Just as Galileo came up against the religious authorities of the day with his proof that the earth went round the sun, so to has Hornardy, many people not wanting to change their "belief system" and sticking with whatever flavour "bible" they happened to favour for the time being.

No skin off my nose if people don't want to change their reloading beliefs, but the noise of the ranters makes it difficult for people to hear.

Originally Posted by John Duxbury

Bullet should be on its own, as a major player.

Indeed

Originally Posted by John Duxbury

You see what I mean?

No I dont. His last post to stocky that I presume you are referencing is quite fine and his points/questions are valid.

Whats more I just went and re-read the other thread referenced, and It was yourself starting the BS by calling him a cunt. SO what's your problem? where is this coming from?

If you historically do not like the way he replies, then why get involved in the thread? It's actually a reasonable discussion.

Originally Posted by gimp

I personally am a big fan of the word "esoteric"


You need another arrow on the left facing the other way which is for "effect size" (low top high bottom) and then a dashed line between the middle 2 sections labeled "unproven above". I'd also separate charge weight above the line and seating depth (juuuuust) below it.
Otherwise, excellent

Nice refinements. I also wondered if the model should be encompassed by a circle with something to the effect of "shooter related factors", to reflect that system precision includes the shooter.

Originally Posted by whanahuia

No I dont. His last post to stocky that I presume you are referencing is quite fine and his points are valid.

Whats more I just went and re-read the other thread referenced, and It was yourself starting the BS by calling him a cunt. SO what's your problem? where is this coming from?

If you historically do not like the way he replies, then why get involved in the thread? It's actually a reasonable discussion.

Well, I disagree, but we did try to have a reasonable discussion again. He wasn't upset at me this time though. I called him a cunt last time.

Originally Posted by earplay

Nice refinements. I also wondered if the model should be encompassed by a circle with something to the effect of "shooter related factors", to reflect that system precision includes the shooter.

This is the tricky bit, because just about everything brought up so far can be explained by the OP not being able to shoot his way out of a bucket if he was inside it. I mean this in a kind way. An explanatory way.

We have to assume for any of this, that the shooter can remove the effect of his abilities as far as possible from the experiment, that he is not part of the system and is not a variable at all.

Originally Posted by Zedrex

OK, let me clarify the first statement you quoted, from a limited data set I've shown that my 243 does not like Boat tail factory ammo from 2 different manufacturers at 2 different weights (100gr Fiocchi and 95g Winchester BST) both these were "all over the place" and using your own logic of "If a 3 shot group is bad that combination is done" I've exceeded that data set gathering by a factor of 7, so I believe my statement holds true that from the data available THIS particular rifle doesn't like BT projectiles, I suppose I could try EVERY boattail out there to gather further evidence but at this point, I don't feel it's necessarry, especially as I have plenty of historical data that the rifle favour flatbase projectiles a la Deer Season XP, ergo my choice of the SST in 95grain to build up a load.

I agree there's a lot that may be assumed but there's also anecdotal evidence of people tuning their loads to match the harmonics of their rifle and logic (and physics) says this must actually be possible, for every action there is an equal and opposite reaction so the frequency/duration of the vibration of the barrel will be directly proportional to the size of the bang, thus tuning to have the bullet leave the muzzle at a certain point of the wave.

My BT (boattail) comment comes from my research and I found a lot of commentary that flatbase bullets are "easier to get accurate" than "boattails that are less forgiving of variables" and yes I'm paraphrasing and no I can't recall the source(s) but it was more than one which was also reinforced by an article for which I posted a link on one of my other threads.

AND I really do get that y'all are trying to help and it's appreciated, it truly is AND I'm still going to question what y'all are telling me, not because I think all y'all are talking shite but because I need to know how you know what you know. @gimp is a prime example of someone who backs up his statements with historical evidence and that gets my attention, as does the fact that he doesn't start crying when I question what he offers. I'm not LOOKING for an argument, I'm seeking a discussion that explores a number of elements without the "because I said so" bullshit

Okey harmonics - now this discussion drops into some things that are hard to observe and provide evidence for. I will link credible sources. However it's important to realise that, at a higher level - with all the theory-based methods for load tuning to match harmonics, the "results" that show up in 3 or 5 shot groups simply disappear when you aggregate 10-30 shots from any of those loads. Achieving good precision simply doesn't need you to try "tune for harmonics". People say they have been doing it for decades, yes. No-one has been willing to provide evidence. Every single large sample test I've seen shows there is no difference. Small sample tests are invalid as we know.

The fact that people have believed something for a long time doesn't mean it is impossible for that thing to be wrong.

Barrels vibrate, but the effect size is tiny, and the cross-velocity vector generated from barrel whip is variable in magnitude and direction. This variability is caused by inherent variations in the pressure-time curve which are present even with the most consistent of loads. Yes "vibration nodes" exist as physical phenomena, but you can't actually take advantage of them through handloading.



https://dsiac.dtic.mil/articles/rand...er-dispersion/ This is a complex description of the actual sources of dispersion - i.e. why don't all your bullets go in one hole? Note all the separate components, of which barrel whip is only one. You can't tune harmonics to get good precision from a shit bullet with an asymmetrical jacket that has COG offset which induces an angular rate of variable magnitude and direction.

Angular rate = bullet wobble, imparted by asymetrical engraving, centre-of-gravity offset from a non-concentric bullet, bullet-barrel interactions (e.g loose spots in the bore or rough spots that damage the jacket)
Cross-velocity = velocity vector perpendicular to the long axis of the barrel


https://storage.googleapis.com/wzuku...nse%20Maps.pdf - this shows modelling that has been aligned with observational data, for the magnitude of the angular rate and cross velocity of a projectile, mapped against the variable pressure-time function out to + - 3 standard deviations. This shows that while low values in both can co-incide at a single pressure-time function value, every load has variability in the pressure-time function, so for example while there may be a low point in the angular rate and cross-velocity at the mean, it is variable as the pressure-time function varies. If your bullets leave the barrel with variable angular rate and cross-velocity, they will disperse and you will get a group rather than 1 hole. Conversely you may find a load that has a high angular rate and cross-velocity at the mean pressure-time function, but they will reduce at pressure-time function values 1-2-3 SD away from the mean. Your bullets will still disperse and you will still get a group rather than 1 hole. You cannot remove the variability in the pressure-time function.

All of this is stuff that is impossible for us to take direct observational measurements of. We have to rely on what we really care about anyway, which is results on paper.



It's a whole hell of a lot easier to dump the heavy theory and modelling though - and just shoot a 10rd group with a powder charge near-to-max and a good bullet seated 0.030"-0.100" off the lands ! (and some other criteria already listed elsewhere)


It's not that "charge weight and seating depth don't matter", it's that - if you pick the right components, there's a window of function you want to be in for those parameters anyway, and it's difficult-to-impossible to detect any precision difference from adjusting those parameters. So far. Maybe something will come along and provide evidence that causes me to update my understanding again. Almost certainly this will happen to some degree.

Another example to assist the OP and those seeking to understand . . .

Many people will start their load development with a charge ladder. Look up manual. See what the starting load is. Load one round at start and then in increment (lots of people use 10 steps) to book max. I do this 90+% of the time.

If you have a really top notch barrel often the result of this ladder is a very good group, often sub MOA. I have seen this with at least a dozen rifles over the years. Makes it hard to explain node theory from that.

If the OPs rifle were mine I'd go to the range with a range of projectiles of known reliability (for accuracy for now) with mid power loads for each and have some fun firing 10 round groups. In 40 or 50 rounds there will be the odd "operator error" ("pulled" is banned in my shooting vocabulary) and see if there are any patterns that emerge. The key is to enjoy the exercise, shooting is fun!

QUestion Gimp.

Why near to max? Especially for those with less experience, would not something closer to a starting load show if the projectile will work? Safer and easier to chuck through a range of projectiles at known safe pressures and pick the one that works best then take it up towards max for your end result?

40-50 rounds is a good days wallaby blasting.... Much funnera

Sorry wall of text. I'm not re-writing or reformatting it.

Originally Posted by Tentman

Another example to assist the OP and those seeking to understand . . .

Many people will start their load development with a charge ladder. Look up manual. See what the starting load is. Load one round at start and then in increment (lots of people use 10 steps) to book max. I do this 90+% of the time.

If you have a really top notch barrel often the result of this ladder is a very good group, often sub MOA. I have seen this with at least a dozen rifles over the years. Makes it hard to explain node theory from that.

If the OPs rifle were mine I'd go to the range with a range of projectiles of known reliability (for accuracy for now) with mid power loads for each and have some fun firing 10 round groups. In 40 or 50 rounds there will be the odd "operator error" ("pulled" is banned in my shooting vocabulary) and see if there are any patterns that emerge. The key is to enjoy the exercise, shooting is fun!

I think you and I are on the same page on that.