Great video on seating depth testing.

[huntnful]

This was a great watch for sure. Some interesting numbers! Take away from it what you wish

My takeaways:

1. This is a 20lb+ straight shank barreled F class rifle with a smaller cartridge, shot by a shooter with a wall of medals. If I think my 10lb magnum rifle will shoot the same, I'm wrong. And if I think I will see the minute differences that he is seeing, I'm wrong as well probably.

2. Average 5 shot groups of .41-.46". The "best" 5 shot group seating depth shot from a .25" group to a .63" group.

3. Once groups were taken to a sample of 33 shots, the WORST small sample size depth, actually became the best, most stable load.

4. From "worst" to "best", the variation is about 10%. I put those in quotations because you can switch sample sizes around and also vary which one is the worst or the best.

5. After 100 rounds of seating depth testing, he almost came to an inconclusive result.



Interesting test for sure. Also why I quit messing with seating depth so much. It'd take me 500 freaking rounds to legitimately prove a 10% change in group size with a magnum rifle. And taking a group from a .7 to a .6 isn't going to kill me any extra animals until you get a LONG ways out.

 

[Jason Snyder]

I listened to a Hornady podcast a while back where they did large sample size comparisons and said you’re wasting time worrying about seating depth.

I’ll be honest, I’ve wasted a lot of components and time over the years.

 

[sndmn11]

I've never understood the seating depth obsession for some folks. I do think it can be a way to manipulate pressure and velocity consistency, but I can't prove it and don't want to try.

 

[huntnful]

I listened to a Hornady podcast a while back where they did large sample size comparisons and said you’re wasting time worrying about seating depth.

I’ll be honest, I’ve wasted a lot of components and time over the years.

I think some bullets are more forgiving to seating depth for sure. Berger hybrids and Hornady ELDM’s certainly fall in that category, and that’s also why I like shooting them haha.

 

[huntnful]

I've never understood the seating depth obsession for some folks. I do think it can be a way to manipulate pressure and velocity consistency, but I can't prove it and don't want to try.

Hahaha I feel the same exact way. For hunting purposes, it just isn’t worth it.

 

[sndmn11]

Hahaha I feel the same exact way. For hunting purposes, it just isn’t worth it.

You shoot 2-2.5x farther than me, and 3x farther than @KickinNDishin . I just set the boat tail where I think it makes sense, do a short string to find pressure, and that's about the extent of it.

 

[Harvey_NW]

In the Hornady podcast they say there's 15-20% variability in 30 shot groups, and still 10% in 50 shot groups. The average of his 99 shots is .7458", the variability at 15% would be .8577" for the high, and .6339" for the low, so each seating depth stayed well within the calculatable variability. If he repeated the test over and over they could flip flop again. So even at 33 shots per test, you couldn't make an assumption that one was better than the other. This is exactly why I quit doing seating depth testing and started doing the painless, lol.

I could see doing some small sample testing in older SAAMI chamber designs to see if there's any significant outliers with a certain combo, like a bullet with a short bearing surface. But understanding the statistics now I would have to prove it with a significant size before I would trust the results. And I just shoot modern or custom chambers and high BC stuff now to mitigate any of those misunderstood variables anyway.

 

[Shooter Mike]

I've never understood the seating depth obsession for some folks. I do think it can be a way to manipulate pressure and velocity consistency, but I can't prove it and don't want to try.

That’s kind of my approach- I use neck tension and seating depth to manipulate pressure and velocity. I’ve only got a few years of reloading experience but never made any noticeable improvements with seating depth changes that were proven in a moderate sample size. Quality components and attention to detail have yielded greater benefits than seating depth for me.

I think people hear things like “finding the node” and since it sounds scientific they accept it, without applying the actual scientific method to see if it’s real. Just my perspective.


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[Castle Rock]

This is a topic that has been done to death
Average shooters with average guns don’t see the difference
People with good gear who can use it see obvious difference

 

[Harvey_NW]

People with good gear who can use it see obvious difference

Until they take it to statistically valid sample sizes, like in this exact video..

 

[Castle Rock]

Until they take it to statistically valid sample sizes, like in this exact video..

What a stupid thing to say, competition shooters are shooting thousands of rounds a year under controlled conditions

 

[Harvey_NW]

What a stupid thing to say, competition shooters are shooting thousands of rounds a year under controlled conditions

I think claiming you have a 1/4 MOA gun because you won a competition with a .25" AGGREGATE of 5 shot groups that doesn't correlate group POI is stupid, but Benchrest shooters do it all the time. Keith is a competitive F-Class shooter and coach himself, but the minute he upped his sample size in a controlled condition testing format, his groups grew to .6-.7". Weird..

 

[Shooter Mike]

I think claiming you have a 1/4 MOA gun because you won a competition with a .25" AGGREGATE of 5 shot groups that doesn't correlate group POI is stupid, but Benchrest shooters do it all the time. Keith is a competitive F-Class shooter and coach himself, but the minute he upped his sample size in a controlled condition testing format, his groups grew to .6-.7". Weird..

Dispersion isn’t real, birds aren’t real, and the earth is flat.


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[SloppyJ]

Personally, I've seen some big swings in precision when it comes to seating depth. Like others mentioned, I think there are some bullets that are more picky than others. Secant vs Tangent Ogive designs certainly make a difference.

I've had an idea to start with a seating depth test first on a known mild load and I'm going to try it with my 300PRC to see if it helps me cut down on time for load dev. I have two little ones running around and if I had somewhere to shoot at my house it wouldn't be bad but I don't so I have to load rounds, wait until I have time to shoot, and then do it all over again.

Let me rephrase my goal with the initial seating depth test, it would be to arrive at a load that I feel is acceptable for my needs quicker. Not to get the ultimate accuracy load because I don't have time to sit around and do all of that right now. Most times I luck out and find something plenty good enough for me.

 

[Formidilosus]

Personally, I've seen some big swings in precision when it comes to seating depth.

With statistically relevant group sizes- 20 to 30 shot groups?

Because I have yet to see seating depth dramatically change 30 shot group sizes (95% probability), regardless of bullet type- that is standard hunting bullets and most common match bullets. Picky bullets are just picky and the real group size is going to be larger regardless- you might/will get a few small “groups” but when repeated over and over- they average out.
Every legit person/group that has bothered actually testing it, is finding the same outcome.

 

[Castle Rock]

With statistically relevant group sizes- 20 to 30 shot groups?


Every legit person/group that has bothered actually testing it, is finding the same outcome.

Can you provide links to any sold studies showing such please
I have consistently proven with large data samples with my own gear that it makes a real difference

 

[SloppyJ]

With statistically relevant group sizes- 20 to 30 shot groups?

Because I have yet to see seating depth dramatically change 30 shot group sizes (95% probability), regardless of bullet type- that is standard hunting bullets and most common match bullets. Picky bullets are just picky and the real group size is going to be larger regardless- you might/will get a few small “groups” but when repeated over and over- they average out.
Every legit person/group that has bothered actually testing it, is finding the same outcome.

Admittedly no, only 3 to 5rd groups. Not dismissing the lack of statistical relevance but to me if you try 5 different seating depths and one stands out head and shoulders above the rest, that's at least something to investigate. I know a small sample size isn't enough to have a definitive answer but it could provide enough info to show you where to direct your efforts.

Are you saying sesting depth is a complete waste of time? What's a solid method to pick a seating depth? If my gun doesn't shoot the bullet I want to use should I scrap it and try something different or move to a new powder charge or completely new powder?

I see a lot of info on how not to do things when reloading but i havent been able to find a good resoruce on troubleshooting when things don't work perfect, which they rarely do.

Honestly just trying to learn here and I have a 300prc to find a load on so I'm very vested in getting to a solution quickly once the barrel is broken in. All of the bullets I'm trying are new to me so I have no previous experience to go off of and it's my first magnum anywhere near that capacity.

 

[Formidilosus]

Admittedly no, only 3 to 5rd groups. Not dismissing the lack of statistical relevance but to me if you try 5 different seating depths and one stands out head and shoulders above the rest, that's at least something to investigate. I know a small sample size isn't enough to have a definitive answer but it could provide enough info to show you where to direct your efforts.

The issue, is that if you run that same seating depth “test”, over and over- the best group will change nearly every very time. And some point every depth will have the smallest group on paper.

Are you saying sesting depth is a complete waste of time?

Varying seating depth by 5-10 thousandths and believing you are doing something? Pretty much a waste of time.

What's a solid method to pick a seating depth?

Painless load development (mine)

I have had multiple people ask me to lay out how I do load development being that what I do is different. Since Shaen @Shooter71 just rebarreled a Tikka 595 in 6XC I thought it would be easy to show how I do it. It’s a Master Sporter with a T3 lite profiled 20” barrel- keep in mind it is a T3...

rokslide.com

If my gun doesn't shoot the bullet I want to use should I scrap it and try something different or move to a new powder charge or completely new powder?

First is understanding/ truly understanding that a single or even a few 3 or 5 shot groups isn’t telling you much- just trying to read tea leaves. A single 10 shot group is about an 80% +/- probability, a 20 shot group is about an 85-90%, and 30 shot is a 95% probability. You need to be shoot a minim of 10 round groups, and counting every single round- there are no flyers or group reduction nonsense.

Then… Load so the bullet is not touching the lands; it load it at Sami spec, or with the boattail at the neck/shoulder junction of the case. Then, if a rifle does not shoot a combo well doing so/ you change powder or bullet. No amount of small changes- powder “ladders”, or seating depth is going to noticeably change the true group size.

 

[Grundy53]

Can you provide links to any sold studies showing such please
I have consistently proven with large data samples with my own gear that it makes a real difference

Coincidentally, I was listening to a Hornady podcast today, and their senior ballistician (Jaden Quinlin sp?) spoke about seating depth. He did repeated ladder tests using 100 round groups at each depth. His conclusion was that it made very little difference, if any. I'm no expert just repeating what I heard from an expert.

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[SloppyJ]

The issue, is that if you run that same seating depth “test”, over and over- the best group will change nearly every very time. And some point every depth will have the smallest group on paper.




Varying seating depth by 5-10 thousandths and believing you are doing something? Pretty much a waste of time.

Painless load development (mine)

I have had multiple people ask me to lay out how I do load development being that what I do is different. Since Shaen @Shooter71 just rebarreled a Tikka 595 in 6XC I thought it would be easy to show how I do it. It’s a Master Sporter with a T3 lite profiled 20” barrel- keep in mind it is a T3...

rokslide.com

First is understanding/ truly understanding that a single or even a few 3 or 5 shot groups isn’t telling you much- just trying to read tea leaves. A single 10 shot group is about an 80% +/- probability, a 20 shot group is about an 85-90%, and 30 shot is a 95% probability. You need to be shoot a minim of 10 round groups, and counting every single round- there are no flyers or group reduction nonsense.

Then… Load so the bullet is not touching the lands; it load it at Sami spec, or with the boattail at the neck/shoulder junction of the case. Then, if a rifle does not shoot a combo well doing so/ you change powder or bullet. No amount of small changes- powder “ladders”, or seating depth is going to noticeably change the true group size.

Appreciate it. I'll try this with my 300prc and see if I can save some time, components, and sanity. I'm all about making this shit as easy as it can get and this would be much easier than everything I've tried so far. It's certainly worth a shot.

Have you found that if you have a good barrel then you can get most everything to work within reason? I'm wondering if this is more dependent on how well your barrel likes a specific bullet or if most things will work if your barrel isn't a turd. I certainly have some rifles that downright do not get along with certain bullets it seems.