Seeking empirical evidence to support or refute powder/seating-depth nodes

[VenatusDominus]

Then what your seeking is a totally different subject than handloading. If you want to know why barrel harmonics affect seating depths then you will have to research or set up your own testing.

The goal of handloading is to find the combination of components that get the results you want in your rifle. The various processes to get there are well documented science.

I believed that seating depth had an effect on barrel harmonic. It just makes sense and I can wrap my brain around it. But recent data with larger samples sizes suggests it might not. If I can get the same accuracy without fussing with seating depth, then why do it? Erik Cortina, Keith Glasscock and many others have posted videos on how seating depth is critical to accuracy. Their conclusions were all based on small groups. Recently Keith tested seating depth effects on accuracy with large groups in a controlled study and discovered his conclusions base on his small groups did not hold up. Yes, Erik wins by fussing over seating depth, no argument, but based on Keith's results, Erik may have shot the same groups with any of the seating depths from his ladder.

 

[Koda_]

I believed that seating depth had an effect on barrel harmonic. It just makes sense and I can wrap my brain around it. But recent data with larger samples sizes suggests it might not. If I can get the same accuracy without fussing with seating depth, then why do it? Erik Cortina, Keith Glasscock and many others have posted videos on how seating depth is critical to accuracy. Their conclusions were all based on small groups. Recently Keith tested seating depth effects on accuracy with large groups in a controlled study and discovered his conclusions base on his small groups did not hold up. Yes, Erik wins by fussing over seating depth, no argument, but based on Keith's results, Erik may have shot the same groups with any of the seating depths from his ladder.

If you understand and agree how seating depth affects harmonics then throw the data that refutes that in the trash.
Anytime you add more shots to a group size you will only increase the group size, that does not at all invalidate small sample sizes. Average group size is a different subject also affected by human error (eg: fliers).
Many times people get lucky, they pick a charge weight, a seating depth to start and its just there... no reason to tune any farther just go hunt. That also does not invalidate small sample sizes.

That whole article on large sample sizes is just one study, a theory at best but not conclusive, and only covers finding optimal combustion but its led to a lot of confusion. Throw that article in the trash. Most rifles will shoot accurately with a random book load, but do not confuse accuracy with precision. Not once did that article mention precision and nobodys going to load 60rds randomly to see if it shoots accurately and hope they get lucky. The OCW test is a better way to find your best charge weight because it uses less ammo and you will validate that small sample size later during fine tuning seating depth, or just shooting that recipe if you got lucky.

The "why" is right under your nose. Your putting too much into this and letting data irrelevant to your rifle needs cloud your results.
Combustion, Harmonics, Ballistics. Thats it.

 

[VenatusDominus]

If you understand and agree how seating depth affects harmonics then throw the data that refutes that in the trash.
Anytime you add more shots to a group size you will only increase the group size, that does not at all invalidate small sample sizes. Average group size is a different subject also affected by human error (eg: fliers).
Many times people get lucky, they pick a charge weight, a seating depth to start and its just there... no reason to tune any farther just go hunt. That also does not invalidate small sample sizes.

That whole article on large sample sizes is just one study, a theory at best but not conclusive, and only covers finding optimal combustion but its led to a lot of confusion. Throw that article in the trash. Most rifles will shoot accurately with a random book load, but do not confuse accuracy with precision. Not once did that article mention precision and nobodys going to load 60rds randomly to see if it shoots accurately and hope they get lucky. The OCW test is a better way to find your best charge weight because it uses less ammo and you will validate that small sample size later during fine tuning seating depth, or just shooting that recipe if you got lucky.

The "why" is right under your nose. Your putting too much into this and letting data irrelevant to your rifle needs cloud your results.
Combustion, Harmonics, Ballistics. Thats it.

I have been using the OCW test since discovering it in 2022 and I have loaded accurate ammo with it. To be honest I would probably not take a shot that is over 600 yards and within that range most of what we are talking about doesn't matter on an 8" vital zone. But I enjoy the scientific side of shooting and enjoy studying and discussing it, even if it may not be needed for practical use in the field.

 

[ShtrRdy]

The following is an example of the method used in the video link I posted in post #30.

On one of the YouTube channels I follow, (Triggered Precision Machine), there was a challenge proposed earlier this year. To fire a 20 shot group within a time frame of 20 minutes while using a bipod on the front and squeeze bag on the rear.

This YouTube channel has had a few shooting challenges over the last couple years and I always give it a try. On this challenge i figured the biggest variable was going to be me. On the minus side l wasn't disappointed, while on the plus side 15 of my 20 shots made a nice ragged hole of 0.421".

 

[VenatusDominus]

The following is an example of the method used in the video link I posted in post #30.

On one of the YouTube channels I follow, (Triggered Precision Machine), there was a challenge proposed earlier this year. To fire a 20 shot group within a time frame of 20 minutes while using a bipod on the front and squeeze bag on the rear.

This YouTube channel has had a few shooting challenges over the last couple years and I always give it a try. On this challenge i figured the biggest variable was going to be me. On the minus side l wasn't disappointed, while on the plus side 15 of my 20 shots made a nice ragged hole of 0.421".

That is a group to brag about for sure, nice shooting!!!

 

[Mike6158]

I've been testing two new rifles. Neither are special. In fact I'd call them sub par for the brand. The first is a Ruger American Gen II in .223. The stock sucks, It feels cheap. But it shoots pretty good. I used David Tubbs final finish on the barrel. I always borescope a new rifle or barrel. It needed help and the "sandpaper bullets" made a difference. YMMV and I wouldn't use it on a custom barrel. 100 yards. Yes the target is upside down but I had already numbered it (at the range) when I started writing on it. 9.29.24 This is the 4th of five 5 shot groups. ES is horrible. SD is horrible. And therefore it might not repeat. I have the next "faster" charges loaded and ready to test. The Tubb breakin is 50 rounds 55 gr. This was shot with 21.7gr Varget and a 62 gr Barnes TTSX. Load data is an attached PDF, one for each target.

This one is a Rem 783 in .308. The 5th group is tolerable and not subsonic at the temperature I was shooting at. The bullets are big ole 190gr Hornady SUB-X's. Powder is 12.1gr Trail Boss for group 5. 5 shot groups. Load data is in an attached PDF. ES 8.8 and SD 3.3. Avg velocity 1169.1. This barrel also had the final finish treatment when I first got it.

So... the way you get verification data is by loading and shooting. And sometimes, you don't get verification because the environment will mess with you. You will mess with you (reloading and shooting).

The more you load and shoot the more you learn bout the rifle, load, and yourself. For the subs, I was looking for the fastest subsonic round. Every frikken load test, the weather cooled off 10 degrees. When you're trying to find the edge of something and the edge moves, that's not good. Now I have 2 sets of data that tell me where the edge of subsonic is at a specific temperature.

That kind of group with a subsonic round is what I wanted but did not expect. I don't expect it to repeat but I don't plan to load it again until it's 90-100 degrees. May it will, maybe it won't.

 

[VenatusDominus]

I've been testing two new rifles. Neither are special. In fact I'd call them sub par for the brand. The first is a Ruger American Gen II in .223. The stock sucks, It feels cheap. But it shoots pretty good. I used David Tubbs final finish on the barrel. I always borescope a new rifle or barrel. It needed help and the "sandpaper bullets" made a difference. YMMV and I wouldn't use it on a custom barrel. 100 yards. Yes the target is upside down but I had already numbered it (at the range) when I started writing on it. 9.29.24 This is the 4th of five 5 shot groups. ES is horrible. SD is horrible. And therefore it might not repeat. I have the next "faster" charges loaded and ready to test. The Tubb breakin is 50 rounds 55 gr. This was shot with 21.7gr Varget and a 62 gr Barnes TTSX. Load data is an attached PDF, one for each target.

View attachment 606648

This one is a Rem 783 in .308. The 5th group is tolerable and not subsonic at the temperature I was shooting at. The bullets are big ole 190gr Hornady SUB-X's. Powder is 12.1gr Trail Boss for group 5. 5 shot groups. Load data is in an attached PDF. ES 8.8 and SD 3.3. Avg velocity 1169.1. This barrel also had the final finish treatment when I first got it.

View attachment 606647

So... the way you get verification data is by loading and shooting. And sometimes, you don't get verification because the environment will mess with you. You will mess with you (reloading and shooting).

The more you load and shoot the more you learn bout the rifle, load, and yourself. For the subs, I was looking for the fastest subsonic round. Every frikken load test, the weather cooled off 10 degrees. When you're trying to find the edge of something and the edge moves, that's not good. Now I have 2 sets of data that tell me where the edge of subsonic is at a specific temperature.

That kind of group with a subsonic round is what I wanted but did not expect. I don't expect it to repeat but I don't plan to load it again until it's 90-100 degrees. May it will, maybe it won't.

Nice shooting, looks like what you are doing works. I am envious of the subsonic .308 load (assume you run a can). I live in the communist state of California and can only dream of someday playing with subsonic .308's out of a can. I am currently working on building a 300 Blackout AR-15 for that very purpose. I recently put one foot in Idaho, so I am one foot closer to the dream.

 

[Csafisher]

I believed that seating depth had an effect on barrel harmonic. It just makes sense and I can wrap my brain around it. But recent data with larger samples sizes suggests it might not. If I can get the same accuracy without fussing with seating depth, then why do it? Erik Cortina, Keith Glasscock and many others have posted videos on how seating depth is critical to accuracy. Their conclusions were all based on small groups. Recently Keith tested seating depth effects on accuracy with large groups in a controlled study and discovered his conclusions base on his small groups did not hold up. Yes, Erik wins by fussing over seating depth, no argument, but based on Keith's results, Erik may have shot the same groups with any of the seating depths from his ladder.

You might want to check out reloading all day on discord. The folks there are a lot more open to the theory's posted here. Many people on this forum have been doing it "right" for 30 years and you simple cannot teach an old dog new tricks….. and many of them don't understand basic statistics.

 

[VenatusDominus]

You might want to check out reloading all day on discord. The folks there are a lot more open to the theory's posted here. Many people on this forum have been doing it "right" for 30 years and you simple cannot teach an old dog new tricks….. and many of them don't understand basic statistics.

Thanks for the advice, I will have to check it out.