Seating depth - does it even matter?

[huntnful]

OK, this is one way to do it, maybe a little imprecise. Kind of seems like 0.25moa adjustment wasn't applied to the second 2 groups?

The was no shift made between the .110 off and .210 off.

Only the two .010 off groups would see a shift. Since I moved it after I shot the first .010 off group.

Sorry if that doesn’t make sense. But I shot it in a circular pattern. Groups 2-6 had the same setting on the turret. I overlayed group 1 & 6 as if I didn’t dial down 1/2 MOA from the first group.

 

[Packmansion]

The was no shift made between the .110 off and .210 off.

Only the two .010 off groups would see a shift. Since I moved it after I shot the first .010 off group.

Sorry if that doesn’t make sense. But I shot it in a circular pattern. Groups 2-6 had the same setting on the turret. I overlayed group 1 & 6 as if I didn’t dial down 1/2 MOA from the first group.

So it doesn't matter?

 

[huntnful]

So it doesn't matter?

Not much, if at all by my eyes. I’ll keep just putting hybrid bullets up near the lands and testing powders.

 

[Packmansion]

We can finally stop talking about seating depth!!!

 

[huntnful]

We can finally stop talking about seating depth!!!

Wishful thinking hahaha. But I’m glad I tested it to see the lack of difference across a LARGE jump.

 

[JGRaider]

Max mag box length or .02 off has worked for me 99% of the time regardless of the bullet or powder used.

 

[Harvey_NW]

As promised, here’s my extreme seating depth test now that season is over.

Since this barrel was still shooting excellent with my N570 144 Berger load, I didn’t want to burn it up more than necessary doing this, so I switched it over to H1000 just for this test.

So this is a new bullet/powder combo that has never been down this barrel. So a good baseline for testing I think.

I loaded .010 off, .110 off & .210 off. All with 65.5gr. H1000.

Started with a clean barrel, and shot 2 foulers.

View attachment 982378
View attachment 982379


Here’s the groups, labeled in the order that I shot them. I waited 5 minutes in between groups and shot the groups as 5 consecutive shots. I dialed down 1/2 MOA after the first group landed a little high.
View attachment 982380

Here’s the velocity numbers in correlation to each depth as well.
View attachment 982382

30 shots into a 1” cone across .200 seating depth difference and 56fps ES encompassing all 30 shots as well.

Great shooting man, thanks for burning the powder and contributing the data set!

Waiting on a few components and then I'll be doing some testing of my own this winter to add.

 

[huntnful]

Great shooting man, thanks for burning the powder and contributing the data set!

Waiting on a few components and then I'll be doing some testing of my own this winter to add.

Yes sir. Happy to contribute.

Now that I think about it, I’m having a 6 creed chambered, and when it’s done I just like to get 100 pieces shot at mild charges. I can do a larger test while doing that as well.

 

[Harvey_NW]

Yes sir. Happy to contribute.

Now that I think about it, I’m having a 6 creed chambered, and when it’s done I just like to get 100 pieces shot at mild charges. I can do a larger test while doing that as well.

That's exactly my plan, except I doubt it will never be sufficient for the masses because you're not in a powder charge node, or your barrel isn't broke in, etc.

 

[wind gypsy]

It does look like it shot a little better 0.010" off. You could probably say it isn't going to make a measurable difference in hits/misses but i dont think it's proof that seating depth doesnt matter.

 

[huntnful]

It does look like it shot a little better 0.010" off. You could probably say it isn't going to make a measurable difference in hits/misses but i dont think it's proof that seating depth doesnt matter.

Agreed. Looks like it doesn’t matter THAT MUCH. Threw much higher SD’s as well.

Again, very small test. I just wanted to see if the bullets started spraying at any point. Which they really didn’t.

20 shots from the 4 deep seating depths still gave a 1 MOA group.

 

[khuber84]

Agreed. Looks like it doesn’t matter THAT MUCH. Threw much higher SD’s as well.

Again, very small test. I just wanted to see if the bullets started spraying at any point. Which they really didn’t.

20 shots from the 4 deep seating depths still gave a 1 MOA group.

Amazing what a well built rifle will do! Berger hybrid ogive is likely the most forgiving bullet for seating depths as well.

 

[solarshooter]

It does look like it shot a little better 0.010" off. You could probably say it isn't going to make a measurable difference in hits/misses but i dont think it's proof that seating depth doesnt matter.

This is why I preach the T test. No need to just look at it, we can quantitatively assess whether or not it's meaningfully different. Just need x/y coords of each shot. @huntnful , I think one of the apps, maybe hornady, will output a table of x/y coords, if you can screenshot me those coords I'll assess it.

 

[huntnful]

This is why I preach the T test. No need to just look at it, we can quantitatively assess whether or not it's meaningfully different. Just need x/y coords of each shot. @huntnful , I think one of the apps, maybe hornady, will output a table of x/y coords, if you can screenshot me those coords I'll assess it.

That’s above my pay grade lol. Keeping it simple here.

Shoot. Look. Nod. Doesn’t matter much. Move on. lol

 

[solarshooter]

That’s above my pay grade lol. Keeping it simple here.

Shoot. Look. Nod. Doesn’t matter much. Move on. lol

OK, too bad. I think some folks will see this and conclude it does matter, a little bit. Would just like to know what the actual data says.

 

[huntnful]

OK, too bad. I think some folks will see this and conclude it does matter, a little bit. Would just like to know what the actual data says.

I do agree with you. And the same people don’t even know what the hell a T-test is (myself included) and will just be forced to believe or not believe the guy putting all the data together and telling them everything is statistically irrelevant because sample size and it won’t change age their mind either way whatsoever anyways lol.

It’s not personal at all. Just being honest lol

 

[JGRaider]

Amazing what a well built rifle will do! Berger hybrid ogive is likely the most forgiving bullet for seating depths as well.

That title belongs to the 139gr Scenar, IME.

 

[BBob]

And the same people don’t even know what the hell a T-test is (myself included)

Must educate yourself young man I ignorant of it as well other than knowing of it and hearing the name from researchers here and there

T-Test in Statistics: Formula, Types and Steps - GeeksforGeeks

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[solarshooter]

I do agree with you. And the same people don’t even know what the hell a T-test is (myself included) and will just be forced to believe or not believe the guy putting all the data together and telling them everything is statistically irrelevant because sample size and it won’t change age their mind either way whatsoever anyways lol.

It’s not personal at all. Just being honest lol

Fair.

It took me a while to wrap my head around the concept. But I think there are many complicated topics in firearms and reloading (and hunting) that take time and experience to understand, and in my opinion this one is pretty vital to testing and interpreting data correctly.

I am no stats expert, but this is my mental model of the concept. Say I have 2 loads, Red and Blue, which are actually slightly different from each other. If I could run a perfect test and take tons of samples, I'd be able to see the following perfect illustrations of these two distinct populations:


But since we live in an imperfect world, I can only take 10 samples of each, and this is what my data shows me:

Not so obvious if those are the same or different now is it? And this is what the T-test let's us quantitatively evaluate.