Thread: Seating Depth Test. Waste of Time?

I enjoy reloading and my process is normally find a decent velocity with good SD and ES and 20 thou jump, then tune seating depth in 3 thou shorter increments.
Did this today at range with 223 I’ve just got shooting 65gr SGK and BM2. 0.2 grain over max.



But…..then I read all of @gimp posts regarding accuracy. Based on that, does this tell me nothing? And if I was really interested in finding out about accuracy, I should’ve just shot some 10 shot groups with the right velocity load that I liked?

Stings a bit to think of all wasted time and components if all this is true.

Not everything you read on the internet is useful

Had you not read that you would be off happily hunting and sending animals to the chiller

Originally Posted by 7mmsaum

Not everything you read on the internet is useful

Had you not read that you would be off happily hunting and sending animals to the chiller

Haha quite the opposite. If I’d read that earlier, and is true, I wouldn’t bother with seating depth tests.

Don't worry have a read of the same question on the accurate shooter forum

https://forum.accurateshooter.com/th...#post-38990711

Originally Posted by johnd

Don't worry have a read of the same question on the accurate shooter forum

https://forum.accurateshooter.com/th...#post-38990711

That thread completely misses the point from the second post onwards

Accuracy has everything to do with a consistent barrel harmonic

Everything you do with ammo alterations/ bedding/ tuners etc is to alter barrel harmonics so that the barrel crown releases the projectile in the same harmonic “place” as the previous shots

A muzzle moves considerably in relation to the point of aim with each shot

The more consistent you can get the harmonic “ wave “ as it travels the barrel the more “ accurate” the rifle

All barrels flex with harmonic waves -watch a 50 fired in slow motion

To repeat - all ammo adjustments alter barrel harmonics, there’s a huge complicated synergy between internal ballistics and barrel vibration/harmonics

Some ask the question……why/how does ammo adjustment alter accuracy, it’s because it alters a barrel harmonic

This article barely scratches the surface

https://www.guntweaks.com/barrel-harmonics.htmlu

A pedant could feed on it for years, a hunter just goes and lives life

Originally Posted by johnd

Don't worry have a read of the same question on the accurate shooter forum

https://forum.accurateshooter.com/th...#post-38990711

Benchrest shooters are insanely obsessed with the idea that tweaking the tiniest aspect of the load (tuning) will produce the best precision for the conditions, going so far as to "tune" during matches by changing the load during relays.

I have not seen any convincing evidence that the "tuning" aspect is anything more than a sport entirely consisting of confirmation bias, playing in the noise, and the results are essentially random as far as the tuning - the winners are the best shooters with the best built guns.

That's my working theory but I'd love to see some meaningful data. That whole thread is nonsense speculation and theory. Just go shoot some 30 round groups with a tuned vs slightly "out of tune" load and prove the difference. It isn't a hard test.




The next question, if there was a difference, would be - can it be resolved and is it practically significant for any particular use? And is it worth trying to identify when the process to genuinely identify it is impractical.

Not too many people in that thread seem to understand the power of statistical testing methods. Once one does, seating depth doesnt matter.

Ironically I'm out happily hunting but I'll put together a post when I'm home next week

@7mmsaum you may need to have a look at that link... it comes up 404

BTW I don't do seating tests. I prefer to jump bullets and test for the velocity I want. Once I have the true velocity I will get my charge weight tweaked with the OBT feature on GRT.
It works for me.

There’s a zillion articles on barrel harmonics

https://huntinginaustralia.au/rifles...rel-harmonics/

Originally Posted by 7mmsaum

There’s a zillion articles on barrel harmonics

https://huntinginaustralia.au/rifles...rel-harmonics/

When it goes "thunk" and the deer drops like a stone on the spot and you have no care for SD or ES.

Originally Posted by TeRei

When it goes "thunk" and the deer drops like a stone on the spot and you have no care for SD or ES.

Legend then keep shooting and share the venison with yer mates

I must admit that Gimp has really upset my peaceful world of reloading.
After the initial “ this is Bullshit “ reaction.
I realised that although my observations aren’t exactly the same, there have been instances of similarities that are freakishly in the same ballpark.
I’m in the throes of doing an extreme makeover of my load development process .
If this proves itself to be both productive and efficient all I can say is .

Bugger………

Originally Posted by Ground Control

I must admit that Gimp has really upset my peaceful world of reloading.
After the initial “ this is Bullshit “ reaction.
I realised that although my observations aren’t exactly the same, there have been instances of similarities that are freakishly in the same ballpark.
I’m in the throes of doing an extreme makeover of my load development process .
If this proves itself to be both productive and efficient all I can say is .

Bugger………

Please do some testing for yourself. I'm intrigued to see the results. I only have limited rifles with which to gather and share data, and any findings such as the .260 powder charge test can only be treated as a case study relevant only to that rifle, powder, bullet, brass etc, until a much larger body of data is available to look at for trends.

If you shot at hv da today that range has some really weird crosswinds and with 20 knt southerly I flagged it , the old porirua range was way more consistent even in a 3o nkt norwester as it was behind and just raised the group an inch or two .