Erik Cortina/Jayden Quinlan Podcast

[jasper2408]

Here is the interview of Jayden Quinlan, Hornady Ballistician, by Erik Cortina. Just a heads up as I am just now viewing it myself.

https://www.youtube.com/watch?v=E2hFMhTRbaY

[37L1]

A lot of discussion over semantics, while mostly saying the same thing, IMHO.

Believe the target is my take away. If you have a load that proves out on "X" amount of "X" shot groups, and you take it out to distance and it still is consistent at "X" amount of "X" shot groups, then take it to competition and it is still consistent, I believe you have a proven load for your barrel.

What if that initial "X" was 3? Is it still statistically invalid?

[grayfox]

Not planning on watching this or another video on that subject. All of them are ignoring the major variable in any multi-shot string, and that is the shooter. No shooter is rock-solid guaranteed to repeat the exact same position, aim, holding and firing every time, so target spread will happen regardless if the load is accurate or not... which is why 10-shot-1-hole (I mean, diameter of the bullet-one-hole) are scarcer than hen's teeth. Especially for the majority of us shooters. Competition shooters come close (with bench rest, 16 lb rifles and hair-triggers, lol) but the only thing that can statistically verify the rifle+load combination is to use them isolated from all other variables. Using a super-heavy mechanical rest that can be verified by objective measurements as being exactly aligned every shot, every time, and an isolated trigger pull that can't disturb the rifle alignment, is the only way to do that, period.
So my thesis is that most of any variation in the load you see on target is your own minor, micro-inconsistencies, multiplied by the yardage out to the target.
And for most of us, we are not anywhere near as good at this as a competition shooter. Nor do we all have $4000-5000 rifles nor all the hours to dedicate to shooting. Someone who does, Lord bless him, but we don't.
All of which is to say that I first of all try to find a load that objectively launches at near-equal conditions from the barrel (ie, constant MV low SD and small ES), ie, mechanical accuracy first; the closer I am to that, the more accurate that load will be. And even though I tend to pull the 4th or 5th shot, or whatever, the load is accurate, only I need better shot consistency.
I know others do it differently, and that's fine, they have their way, I have mine.

[StoneHendge]

then take it to competition and it is still consistent, I believe you have a proven load for your barrel.

That's cutting edge - I hope it doesnt cause too much controversy!

[SCJim]

. Competition shooters come close (with bench rest, 16 lb rifles and hair-triggers, lol) but the only thing that can statistically verify the rifle+load combination is to use them isolated from all other variables. Using a super-heavy mechanical rest that can be verified by objective measurements as being exactly aligned every shot, every time, and an isolated trigger pull that can't disturb the rifle alignment, is the only way to do that, period.
So my thesis is that most of any variation in the load you see on target is your own minor, micro-inconsistencies, multiplied by the yardage out to the target.

I agree 1000 percent. When shooting my .22 I minimize my contact with the rifle and use a "pinch" trigger pull. Once I have the crosshairs on target my forefinger on the trigger and my thumb on the trigger guard is my only contact. All of my attention is on the wind flags once the rifle is set, just waiting for the right moment to pinch that trigger. Now you can't do that with a AR with a 5 pound trigger pull, but my goal this year is to find and perfect a minimal contact technique

[Harpoon1]

[grayfox]

Maybe so.
However, for 98% of shooters, if the largest variables (shooter/position/grip/etc-oriented uncertainties) are left in the equation and not accounted for, then any purported statistics will mean, well... close to zero.
37's method above will satisfy most shooters except for the strictest competitive.

[jasper2408]

Just to get off the thread subject for a second, in the first video the other fella, not Jayden, states that the group dispersion also shows up in bolted down barreled actions, maybe not as much as if a shooter were firing the rounds, but it still does it. It is around the 25-26 minute mark. This would take out the shooter variable completely.

[JASmith]

A lot of discussion over semantics, while mostly saying the same thing, IMHO.

Believe the target is my take away. If you have a load that proves out on "X" amount of "X" shot groups, and you take it out to distance and it still is consistent at "X" amount of "X" shot groups, then take it to competition and it is still consistent, I believe you have a proven load for your barrel.

There was another comment about the inability of the shooter to replicate all the nuances of hold, wind, etc.

Nonetheless, showing consistency over multiple days and variety of conditions proves consistency for BOTH the laod and the shooter.

[37L1]

Best comment was that your group never gets smaller as you add the number of shots.

[SCJim]

Best comment was that your group never gets smaller as you add the number of shots.

ain't that the truth. I use 5 rounds to get velocity averages. 2 + rounds for seating depth testing (I adjust the bullet depth at the range) but for evaluation of the finished load 20 to 50 rounds is necessary in my opinion. In regard you your comment, these are screen caps from OnTargets extended target data taken at 5, 10 and 25 shot points of one of my targets from last weeks .22 ARA factory match

[grayfox]

This might be true, however it is also true of any bell shape, normal-distribution, since the sample/total population size increases. As more and more of the potential bell-shaped universe is produced, the normal curve will fill in extending more out into the respective wings, as it were. So ES might indeed increase but I would say that is not as important to most shooters.
What is more important is what happens to the mean and SD. Do they shift, change or alter in any significant way? Those values tell more about whether the load/rifle/shooter combo is accurate and consistent, or rather, the level of same.
And is the particular bell-shape broad or narrow? But that is indeed the reason to look at the SD.

ES might tell the shooter what dispersion could occur out at a far distance, probably mostly in the vertical, but at some finite shot count (for that target). For those who are shooting several shots out to a distance -- some on here suggest that would be 500 yds+... Or something.

[SCJim]

ES might tell the shooter what dispersion could occur out at a far distance, probably mostly in the vertical, but at some finite shot count (for that target). For those who are shooting several shots out to a distance -- some on here suggest that would be 500 yds+... Or something.

This is a unpopular opinion these days but I think SD and ES #'s are overrated. I have loads with triple digit ES's that I use out to 850 yards that I used to get my long range master card. Still working on my High Master. My .223's pet Varget/ 80 SMK load has a ES of close to 200 FPS but I shoot high 190 scores with it at 600 yards. I quit living by the chrono when developing that load and it gave me a .3 MOA 10 round group @ 300.

What I do like is finding flat spots in the velocity curve. What I mean by that there there is a small differences in velocity at a given charge weight plus or minus a couple of tenths of a grain of powder. To me that seems to allow for temperature differences. But once past getting the velocity curve on the initial charge workup I ignore the chrono numbers and just let the target tell me what I need to know

[muvef]

Cortina wants to argue about how to tune and clean his $10,000 guns. His methods just don't/won't work with a $200 off the shelf Grendel barrel and never will.