Lessons Learned on the Final Stage of the Journey to Subsonic Sub-MOA Accuracy with the 300BLK

[bangbangping]

More than 1000 words right there.

[dellet]

1. As for the scientific method, there are a number of flaws:

• * Your testing covered six months, half a year of seasonal changes. Could that affect the results?

• * Day to day variations in conditions (yours as well as at the range)

• * Random headstamps and trim lengths. This could result in clusters of good/bad groups.

• * Given the point above, I assume other loading anomalies. For instance, what was the shoulder bump? Was it consistent?

• * Changes to the brass itself over the life of the test. You don't mention how much brass you had and how many times each piece was reloaded.

• * Barrel wear over the life of the test. You should do round-robin testing to eliminate this factor.

• * Changes in your shooting ability over the life of the test. Again, you should do round-robin testing to eliminate this factor.

• * Extrapolating from a single barrel/bullet to all barrels/bullets. Can't be done, regardless of your math, because you can't derive a universal equation from a single test. If you want to claim a universal truth, at least try several barrels, multiple bullets, and shoot sub and super. From a machine rest. And tens of thousands of shots, with all other variables eliminated or accounted for.

• * Human bias. You assumed what would happen before you tested, and then you tested your assumptions yourself.

Human bias? I pointed out I started at the low end of the harmonic curve to test dispersion patterns on purpose. I admitted to that bias up front, which is about all you can do in any scientific experiment.

The real point is that mathematicians and people who work in military ordnance have known about this barrel harmonics curve for nearly (300) years. Every USAF fighter pilot, including my father, is briefed on it in gunnery training. That was (50) years ago. I knew about this curve a year ago when I tried getting decent load information to refine my tests to find a sub-MOA subsonic load and I all got was heckle and jeckle criticism from guys like you. I got the twenty question treatment. That suggested to me that you guys really didn’t know, so I set about over the last year to collect the test data necessary to demonstrate one more time what the barrel harmonic curve looks like.

You argue my test results are flawed and then you cite a laundry list of items that you claim should effect my conclusions instead of the nature of my test data. However, if it were possible to refine and improve upon those laundry list items, it would only make my dispersion patterns better, not worse. This is actually called arguing both sides of the fence by the way. In legal circles it’s called collateral estoppel and is grounds for having your whole argument thrown out.

You claim I should have control over the weather before my test data can be considered valid. This means you don’t know the difference between the effect of a first order variable and something that could barely be considered a fourth order variable, and I’m supposed to take you seriously.

My cartridge lengths were the best I had and I admitted to the fact that there was some variability up front, but look at my results. I achieved sub-MOA data without perfectly uniform cartridge trim lengths. Cartridge trim length is a third order variable, by the way. Had my trim lengths been better, my patterns would have been tighter, which only supports my conclusion on barrel order harmonics – a first order variable.

Finally, I held back on my discussion of the harmonic curve between maximum COL and zero freespace, but you accepted my treatment of the subject at face value. If you had been able to do the math yourself, you would have been able to recognize it and you would have pointed it out. It doesn’t effect the conclusion, but it does effect the relative value of the result. This means you are trying to argue things dogmatically that mathematically you don’t understand.

You don’t know the difference between a first order variable and a third order variable. I’m through with you.

And finally: "Driving at 35mph?" Mixed metaphor. I want my subsonics to stay subsonic.

Look Sunflower, you have quite a few things working against you like pride, arrogance and a hard head. You have a good idea and possibly the skills to work it through to the end, but you just don't have the experience and knowledge to begin to see the variables you are missing.

Your statement that since you were able to achieve sub MOA in spite of those variables is a joke. You honestly don't know if those unknowns hurt or helped your final results.

From all your words and graphs and charts, I am pretty certain you really do not comprehend what all happens, when and what the order is between the time the primer is struck and the bullet hits the lands. This is the next gap in your knowledge that needs to be filled.

All your worrying about CTBO and the calculations you made are all half baked, simply because you did not sort bullets by base to ogive and bearing surface lengths. You have no way of knowing if your .001" movement of the bullet changed the time it took hit the lands because of the distance traveled change or the burn rate change of the powder moving it at a different speed.

In short, what you found was a way to put on a chart, the results of a precise small movement and how it helped to average out all the other inconsistent variables to achieve a certain goal of mediocre results.

Then you get all butt hurt about it when you're called on it.

[gds]

Man, talk about a way to make shooting no fun.

[SwampDog_13]

Man, talk about a way to make shooting no fun.

You ain't kidding! I've got my hooked on phonics on order just so I can read these long posts but I think the holiday might slow down the shipment.

[rebel]

OK, so harmonics are affected by more than a few parameters, subsonic or supersonic really doesn't matter. This is what you, me and all of us wish to achieve. Precision and accuracy, which are to different things by definition. These groups were shot on the same morning, with the same bullet but 2 different powders. Very frustrating for him because he is not willing to just go with it. He has also never repeated this performance. I have been shooting distance a long time - he may never shoot this well with this rifle again. Shame, it was just born. 6.5 x 47 L 140 gr ELDM at 300 yards IMR 4350

100 yards H4350, same bullet

Now neither powder shot as well at 100 or 300 as the groups posted.
Lapua same lot new brass. Both powders are one lot obviously. CCI 450 primers same lot. Bullets set .010 off the lands. But his test is greatly flawed for future load data and what is actually occurring with these loads - anyone care to weigh in as to why?
What doesn't make these fantastic groups definitive and why did BR BR Bob and and I tear his playhouse down after he shot them?
Batman........anyone?
I'll answer that - while his components were top notch, there is not enough data there to even to begin to base a theory on.
You can brag a bit, but if you can't do it again, and again, and again - then the rifle don't shoot like that.
Gotta be a wizard to know that crap

[dellet]

OK, so harmonics are affected by more than a few parameters, subsonic or supersonic really doesn't matter. This is what you, me and all of us wish to achieve. Precision and accuracy, which are to different things by definition. These groups were shot on the same morning, with the same bullet but 2 different powders. Very frustrating for him because he is not willing to just go with it. He has also never repeated this performance. I have been shooting distance a long time - he may never shoot this well with this rifle again. Shame, it was just born. 6.5 x 47 L 140 gr ELDM at 300 yards IMR 4350

100 yards H4350, same bullet

Now never powder shat as well at 100 or 300 as the groups posted.
Lapua same lot new brass. Both powders are one lot obviously. CCI 450 primers same lot. Bullets set .010 off the lands. But his test is greatly flawed for future load data and what is actually occurring with these loads - anyone care to weigh in as to why?
What doesn't make these fantastic groups definitive and why did BR BR Bob and and I tear his playhouse down after he shot them?
Batman........anyone?
I'll answer that - while his components were top notch, there is not enough data there to even to begin to base a theory on.
You can brag a bit, but if you can't do it again, and again, and again - then the rifle don't shoot like that.
Gotta be a wizard to know that crap

It looks to me like the difference in those two groups is about a foot.

[rebel]

That's my foot dummy!

[smustian]

That's my foot dummy!

Either you have TINY feet or that is one big ass target. They look the same size in the picture. For the sake of argument we will say that your feet are not small which would make your group about 3" at 100 yards. Since there is no real measurement tool shown then I must be right. Better luck next time Rebel.

[Netpackrat]

[rebel]

That's my foot dummy!

Either you have TINY feet or that is one big ass target. They look the same size in the picture. For the sake of argument we will say that your feet are not small which would make your group about 3" at 100 yards. Since there is no real measurement tool shown then I must be right. Better luck next time Rebel.

Not my group. Wish I could claim it. Read smus, read!