Here to stir pot on seating depth

[Ledzep]

35 shots at each seating depth. ES/SD data was not meaningfully different. 8-9.5 fps SD across the board.

This difference in mean radius at 200yd (distance it was shot) is worth roughly 0.1 MOA total group size from best to worst.

 

[Taylorbok]

35 shots at each seating depth. ES/SD data was not meaningfully different. 8-9.5 fps SD across the board.

This difference in mean radius at 200yd (distance it was shot) is worth roughly 0.1 MOA total group size from best to worst.

View attachment 7980394

In my experience a seating window is roughly .006" wide You could have by chance skipped over your really killer depth. I usually pick an arbitrary starting point and seat .003" deeper for 10 groups, I usually find a really good place in there
Try it and see what happens

 

[Ledzep]

In my experience a seating window is roughly .006" wide You could have by chance skipped over your really killer depth. I usually pick an arbitrary starting point and seat .003" deeper for 10 groups, I usually find a really good place in there
Try it and see what happens

Knock yourself out. I'm not repeating 35-shot test groups every .003".

Everything I have seen up to this point says that big swings in performance as the result of small incremental changes is usually the product of interpreting results of small sample noisy data. YMMV.

 

[timintx]

Knock yourself out. I'm not repeating 35-shot test groups every .003".

Everything I have seen up to this point says that big swings in performance as the result of small incremental changes is usually the product of interpreting results of small

Were you controlling barrel temp ? Are you saying you shot 35 rounds in a row without stopping ?

timintx

 

[Rocketvapor]

Following this discussion.
I'm still working to fine tune a load for the Berger 85.5 in my 22 Nosler.
Whether or not seating depth/jump has any great effect, I want to eliminate as much as I can.
Not a great shooter but don't want unwanted variables skewing my results. Using a seating stem (Hornady VLD stem) I was getting some variation in overall length.
Went through a few 100 count boxes of the 85.5 and found 0.010" variation in BTO with MOST centered. One box of 100 were all at the short dimension. One box mostly at the long dimension. Started on a 1000 box and most were at the medium dimension.
That gives me +/- 0.005" and about what I was finding in COAL of my rounds.
Next I need to check my reloading to see if using bullets with equal BTO ( the medium length ones) fixes my COAL variations. If not is there a tool that can actually seat using the ogive @ the land diameter instead of using a narrow seating stem?
It wouldn't be a lot of trouble (time for me is free) to seat a little long with a seating die then final seat with a comparator insert fitted to a junk die.
Any thoughts?
Case in picture is sized to pass a 0.217" pin, light chamfer to break the sharp edge so about 0.218" ? My bore is 0.219/0.224.

 

[Taylorbok]

Knock yourself out. I'm not repeating 35-shot test groups every .003".

Everything I have seen up to this point says that big swings in performance as the result of small incremental changes is usually the product of interpreting results of small sample noisy data. YMMV.

I don't shoot 35 round groups. I shoot 3-5 shot groups. I have been able to repeatedly get tighter groups using this method.

 

[Ledzep]

Were you controlling barrel temp ? Are you saying you shot 35 rounds in a row without stopping ?

timintx

I can't remember for this specific set of tests. All groups were the same and were either 3x 10's and a 5 or a 20x and a 15x with time to cool to ambient between. All in a pneumatic return accuracy fixture ("rail gun") bolted to a pedestal in a 200yd indoor tunnel with Oehler acoustic targets and fixed chronograph screens. ETA: For that matter, I also did several tests where I shot 7x 5 shot groups then repeated the test with a single 35 shot group and the results were indistinguishable. 1.250" straight profile barrel.

I don't shoot 35 round groups. I shoot 3-5 shot groups. I have been able to repeatedly get tighter groups using this method.

You're playing in noise. Look up statistical analysis or statistical process control and determine for yourself how many samples need to be in a test to accurately represent the total population of that load, thus giving you the ability to accurately quantify one load vs. another. Dig through my post history, I've addressed this a few different times here. All of the sinusoidal, "node", etc.. BS fades away when the sample size is increased and you start getting smooth lines and "swoops" data sets like the graphs I posted above.

Or don't. I doesn't hurt me for you to believe in superstition.

 

[timintx]

Thanks led zep for your reply , what I have found with large samples is if I clean the barrel , season with 7 rounds and then shoot no more than 9 rounds to check my ES , I can repeat it over and over if temp is controlled , but the barrel must be recleaned to repeat it . With that said the reality is after 16-20 rounds through the barrel all bets are off. I have never had single digit ES for more than 12 rounds in a row . So when I settle on a depth it is only within these perimeters. This is why large shot samples without cleaning can give some bad numbers even though it is a good seating depth .

timintx

 

[acudaowner]

I see the bullets I load them I shoot them and no excuses I shoot good I get good results I shoot like crap nothing is going to make the groups any better . no where in that did seating depth fix or hurt anything .

 

[timintx]

I see the bullets I load them I shoot them and no excuses I shoot good I get good results I shoot like crap nothing is going to make the groups any better . no where in that did seating depth fix or hurt anything .

How do you distinguish why the group was bad ? Or good?

timintx

 

[Near miss]

I am myself battling with Hornady 75s as where I could easily get scenar 77s to group 0.4moa median with my AR, the 75s are doing .8 to 1.2moa depending on charge.

I have now tried multiple powder charges and seating depths, I doubt I can improve much more.

My next desperate attempt is to load few outside mag length to see if putting them close(r) to lands will help.

 

[straightshooter1]

From what I have tested , seating depth primarily effects 2 things . Velocity variation and also causes a random dispersion at certain depths . The volume of powder can effect this as well . At certain volumes the velocity variance can be effected less or more .I have not found a bullet yet that was not effected by this variable. Average change in jump has been approximately .004-.005 before small spikes in velocities start to appear again but again this depends on the volume occupied by the powder at the time .

timintx

It has not been in my experience that .004-005" changes in "jump" has had any effect. In fact, I've gone as much as .033" change in jump (due to throat erosion after 2k rounds fired in my .308) and saw very little change where I continued to get nice small groups as when I started, keeping the same seating depth all that time. When I change seating depth that much, I do see changes in velocities and POI's and shapes of the groups.

 

[orkan]

It has not been in my experience that .004-005" changes in "jump" has had any effect. In fact, I've gone as much as .033" change in jump (due to throat erosion after 2k rounds fired in my .308) and saw very little change where I continued to get nice small groups as when I started, keeping the same seating depth all that time. When I change seating depth that much, I do see changes in velocities and POI's and shapes of the groups.

It's important to quantify the "effect" we're discussing here.

If 1/2MOA or marginally less is the delta, then I agree... often a huge swing in seating depth can produce no appreciable change in POI or group size. However, if we shrink the delta to 1/4 MOA or better, then you'll rarely see a 30 thousandths jump have no effect. Generally when you're shooting quite small, a 10 thousandths change in seating depth will produce some measurably different results.

 

[straightshooter1]

It's important to quantify the "effect" we're discussing here.

If 1/2MOA or marginally less is the delta, then I agree... often a huge swing in seating depth can produce no appreciable change in POI or group size. However, if we shrink the delta to 1/4 MOA or better, then you'll rarely see a 30 thousandths jump have no effect. Generally when you're shooting quite small, a 10 thousandths change in seating depth will produce some measurably different results.

That's a good point. So, just for reference, for my .308, I tend to get 1/3 MOA or better. And the only other cartridge I load for is a 6.5 PRC and I get the same kind of benefit keeping the seating depth constant regardless of jump as the throat erodes . . .

. . . until I can see my groups opening up, anyway.

Since I only load for these two calibers/cartridges, I do wonder how much this holds true for other cartridges and/or calibers???

Though, listening to Speedy talk about what he does with his competition guns, he leaves the seating depth constant for the life of the barrels. . . . like for 6mm's.

 

[orkan]

That's a good point. So, just for reference, for my .308, I tend to get 1/3 MOA or better. And the only other cartridge I load for is a 6.5 PRC and I get the same kind of benefit keeping the seating depth constant regardless of jump as the throat erodes . . .

. . . until I can see my groups opening up, anyway.

Since I only load for these two calibers/cartridges, I do wonder how much this holds true for other cartridges and/or calibers???

Though, listening to Speedy talk about what he does with his competition guns, he leaves the seating depth constant for the life of the barrels. . . . like for 6mm's.

I don't chase the lands either. I chase precision/accuracy. Sometimes that requires a seating depth adjustment across the life of the barrel... sometimes it doesn't. Seems to be pretty specific to the barrel I'm working with. I haven't noticed a trend on that, cartridge-to-cartridge. ...and I load for a few different things:

 

[Ledzep]

Thanks led zep for your reply , what I have found with large samples is if I clean the barrel , season with 7 rounds and then shoot no more than 9 rounds to check my ES , I can repeat it over and over if temp is controlled , but the barrel must be recleaned to repeat it . With that said the reality is after 16-20 rounds through the barrel all bets are off. I have never had single digit ES for more than 12 rounds in a row . So when I settle on a depth it is only within these perimeters. This is why large shot samples without cleaning can give some bad numbers even though it is a good seating depth .

timintx

My experience has been that SD's can start with 3-10 rounds extremely well, extremely poorly, or somewhere in between, but in typical cartridges (.308 or 6.5 Creedmoor for example) that aren't radically overbore, fouling effects don't rear their head for several hundred rounds, and by 35-50 shots repeat tests will converge to the same end result. The first 10 of one may be an SD of 5, the first 10 of the next may be an SD of 17, but by the time they hit 35 rounds they've both settled to 10.

I have lots of Varget, H4350, Hybrid 100V, and probably other powders groups/sets with a 140gr 6.5 Creed that have single digit 35-shot SD's. Lots more yet with 6 ARC, .308, and .300 PRC.

Nothing against cleaning. I think properly done it usually takes a single fouling round (until the barrel is well on its way to dying) to return it to normal, but for a lot of the tamer cartridges it's really not entirely necessary to clean more often than once every few hundred rounds. In the smaller cartridges like Valkyrie, 6 ARC, .223, etc... it may be more like thousands of rounds. With certain overbore magnums, things get wonky within 50-75 rounds. YMMV

 

[kthomas]

Seat .025-.045 off the lands. Don't worry about it again.

I'm not going to say it completely doesn't matter, but in terms of things you can change to affect precision, seating depth is one of those that takes a lot of testing to produce small improvements.

This.

I used to obsess a bit over bullet jump, but through my own extensive testing, I've found that it matters a lot less than I once thought. Maybe with specific projectiles and cartridges it matters more, but for 6BRA and 6.5 Creedmoor and hybrids, I've found it doesn't matter much.

For Berger Hybrids (which is my main staple), I'll seat them at 10 thou off the lands and maintain that exact same COAL as the throat erodes. No chasing lands. It doesn't matter.

I've also done my own extensive testing with tuners (with centerfire, not rimfire), and the results are much less impressive than most think...

 

[kthomas]

In my experience a seating window is roughly .006" wide You could have by chance skipped over your really killer depth. I usually pick an arbitrary starting point and seat .003" deeper for 10 groups, I usually find a really good place in there
Try it and see what happens

You must have a hell of a time chasing lands.

 

[Near miss]

Here is my view into the matter.
Conclusion up front:
Accuracy seems to be a lot more about the bullet / barrel combination than any amount of powder or seating depth.

I say this as a new reloader who has shot 2k precision ammo this year.

I have done a load for my MR223 for:
Berger 70VLD, averaging mean radius 0.3moa for all loads (but did not get the MV I wanted and availability is poor.)

Scenar 69, averaging mean radius of 0.36moa and with the best load it was really good but wanted better BC and more weight.

Scenar 77, I do not have solid data for this as I quickly noticed what works so I did not have to manage any data, but it does around .36 also. And at 2700-2740FPS, so I can get really good performance out of 16".

And latest, Hornady 75 BTHP.
Averaging 0.83moa mean radius. My handloads with it are below the accuracy of cheapest bulk I can get.

For reference, my Geco Target does .62moa

All data above is consisted of 5 shot groups of 10 or plenty more.
The data against powder and seating depth with Hornady 75:

Here the end results (mean radius) go into quite good gaussian line, meaning that it all is pretty much the same crap, with more or less luck.

Here is what 40mm/1.38moa mean radius means:

What 18mm/0.62 mean radius shows like:

Control group from that day, done with scenar 77s, including cold bore (middle one)
Mean radius of 9mm/0.31moa

 

[MarkyMark007]

like all threads here; loaded with people who refuse to have statisticaly significant sample size, and people who see a precision potencial in 0.001' increment from their shitty 2MOA AR's...

 

[MarkyMark007]

If not is there a tool that can actually seat using the ogive @ the land diameter instead of using a narrow seating stem?

if you want to have consistant OGIVE, you must get dies with seating sleeve (redding) or die chamber (forster) (or willson die for arbor press), in which you put whole cartridge into the die, not only bullet.
and than housing of this sleeve/chamber must be firmly in contact with shellholder in your press when seating the bullet.
only with this approach you will get consistant OGIVE dimensions of your cartridges no matter of your bullet seating force.

 

[Near miss]

like all threads here; loaded with people who refuse to have statisticaly significant sample size, and people who see a precision potencial in 0.001' increment from their shitty 2MOA AR's...

If I want to find a load that groups 1moa (around .3moa mean radius)
Why would I make samples of 30 when I can clearly see with less results what does not work?

Just as if you wanted to see if a bullet goes through a body armor, you kind of see quite clearly the first hit if it goes straight through. I hope you do not need to hit another one (or 30, to get statistical signifigance) again and hope one of those bullets does not pass?

Right now I can already see even from those measly 5 shot groups that I cannot get the group size to drop to half of what they are now without drastic changes.
And to be honest, I can spare none that are practical.

Btw, here is my seating depth test with scenar 77s. I just wanted to shoot a lot that day and made up a test.
60 shots, 1.97moa. So kind of 2moa rifle, at its worst, but still. The number 5 is mag-length. Around 2.260-2.264, as I do not use COAL as reloading datapoint, but the micrometer setting itself.

 

[Haney]

like all threads here; loaded with people who refuse to have statisticaly significant sample size, and people who see a precision potencial in 0.001' increment from their shitty 2MOA AR's...

You and your bullshit posts really suck the life from these threads .

 

[Gustav7]

If I want to find a load that groups 1moa (around .3moa mean radius)
Why would I make samples of 30 when I can clearly see with less results what does not work?

Just as if you wanted to see if a bullet goes through a body armor, you kind of see quite clearly the first hit if it goes straight through. I hope you do not need to hit another one again and hope one of those bullets does not pass?

Right now I can already see even from those measly 5 shot groups that I cannot get the group size to drop to half of what they are now without drastic changes.
And to be honest, I can spare none.

I don't think anyone has said you can't rule out horrible groups, especially when looking at powder charges or bullet combos. I believe what @Ledzep and others are trying to say is that when you do 1-2, 5-shot groups across differing bullet seating depths and one or two of those depth shows you a "better" group that is 1/4 moa better than the other groups, its hard to say with actual statistical confidence that they're truly better, or if you are simply looking at a statistically biased result. Meaning if you did 20 more 5-shot groups, the group you thought did better may not be the actual better grouping, or it may, or it may be the same.

As to the comment you replied to lol, I just ignore shit like that.

My goal for my rifles is usually in the 1/2-3/4 moa range for multiple 5-shot groups. I have done and still do seating depth tests, but its not because I necessarily believe in them, but its good practice for me, and I'm curious if I ever get something that does stand out. My last seating depth test for my Lothar Walther barrel'ed AR showed no real difference across 8 seating depths, running 2, 5-shot groups per depth. Best group was .45moa and worst was .79moa at 175yds. But no clear winner. Now I admit I may not be able to shoot the difference required to see that, so maybe it only doesn't matter for someone like me...but it has always ended up being more about practice and less about finding anything significant. It does interest me, so I'm very excited to see @Reloadingallday5 data set and info on it.

 

[Rocketvapor]

if you want to have consistant OGIVE, you must get dies with seating sleeve (redding) or die chamber (forster) (or willson die for arbor press), in which you put whole cartridge into the die, not only bullet.
and than housing of this sleeve/chamber must be firmly in contact with shellholder in your press when seating the bullet.
only with this approach you will get consistant OGIVE dimensions of your cartridges no matter of your bullet seating force.

Thanks,
Looking at the Redding Competition Seating Die for the 22 Nosler, part number 55768, and VLD stem 55742. The stem appears to be of larger diameter than the Hornady stem and contact the bullet at a larger diameter. This seems like it would reduce/eliminate seating depth variance caused by ogive variations in the pointy end of the bullet (forward 1/3rd).

 

[MarkyMark007]

Thanks,
Looking at the Redding Competition Seating Die for the 22 Nosler, part number 55768, and VLD stem 55742. The stem appears to be of larger diameter than the Hornady stem and contact the bullet at a larger diameter. This seems like it would reduce/eliminate seating depth variance caused by ogive variations in the pointy end of the bullet (forward 1/3rd).

no. you didnt understand.

https://www.redding-reloading.com/images/stories/PDFfiles/seaterquickstart.pdf

https://www.forsterproducts.com/pdf/instructions/br_seater_die_instructions.pdf

 

[MarkyMark007]

You and your bullshit posts really suck the life from these threads .

those threads are allready dead because of the bunch of retarded people.

 

[MarkyMark007]

As to the comment you replied to lol, I just ignore shit like that.

actually, you respond to post in which person doesnt understand statistics and is making conclusions from his 2 moa targets...

who is here retarded?

 

[Rocketvapor]

Guess I don't understand then.
Measuring BTO, bullet only, I get a 0.010" range on the Berger 85.5 (haven't checked other bullets yet).
If I want to get a consistent CBTO, ignoring OAL to the tip, it seems I would have to seat using the bullet diameter closest to the land diameter.
Seating based on the forward end of the bullet, relies on the shape of the ogive and manufacturing variations.
Precisely guiding the case and bullet during seating does sound better.
I can find my lands pretty well but seating depth just seems to depend on the bullet length behind the ogive (at land diameter).
Using the median BTO all the 85.5s would be withing +/- 0.005" seating depth. Maybe that's good enough.
My other favorite bullet is the plastic tip 88 ELD. I imagine it will also have BTO variations when I get back to measuring it.


Not one of those retarded 2 MOA shooters.
Maybe 1 MOA or a little over @ 600 ( I always seem to get at least a couple 9s).

 

[Gustav7]

actually, you respond to post in which person doesnt understand statistics and is making conclusions from his 2 moa targets...

who is here retarded?

Dude, if you're going to call people retarded, at least get your grammar correct.

I didn't agree with the "2moa shooter" above...did you even read what I put? I'm actually agreeing with you...at least in concept.

Back to the topic though...

 

[orkan]

The difference between this rifle shooting consistent .1's-.2's and shooting .3's-.4's was only 15 thousandths of seating depth.

 

[NH4X]

Following this discussion.
I'm still working to fine tune a load for the Berger 85.5 in my 22 Nosler.
Whether or not seating depth/jump has any great effect, I want to eliminate as much as I can.
Not a great shooter but don't want unwanted variables skewing my results. Using a seating stem (Hornady VLD stem) I was getting some variation in overall length.
Went through a few 100 count boxes of the 85.5 and found 0.010" variation in BTO with MOST centered. One box of 100 were all at the short dimension. One box mostly at the long dimension. Started on a 1000 box and most were at the medium dimension.
That gives me +/- 0.005" and about what I was finding in COAL of my rounds.
Next I need to check my reloading to see if using bullets with equal BTO ( the medium length ones) fixes my COAL variations. If not is there a tool that can actually seat using the ogive @ the land diameter instead of using a narrow seating stem?
It wouldn't be a lot of trouble (time for me is free) to seat a little long with a seating die then final seat with a comparator insert fitted to a junk die.
Any thoughts?
Case in picture is sized to pass a 0.217" pin, light chamfer to break the sharp edge so about 0.218" ? My bore is 0.219/0.224.

Now , use a bullet comparator and measure cbto ( case base to ogive )........I'd bet money those three different batches in your picture are within .001 of each other and THAT'S what really matters ,if it matters at all......assuming ,somewhat equal bullet seating pressure . Using COAL measurements, like in your picture ,with any hollow point will drive one to pulling their hair out......if they let it. Fellow 22 Nosler shooter here.

Also, one can go down the rabbit hole of sorting bullets by oal,base to ogive ,and weight, iffin they want to not " leave anything to chance "...... But ,it will only matter,maybe, if the rifle and shooter can shoot the difference.

 

[Rocketvapor]

Thanks.
Agree, OAL is almost worthless. I will, in a couple days, load another batch and check CBTO out of the seating die to see if the BTO makes any difference in CBTO. I hadn't been checking that. Getting a consistent JUMP might make a little difference at my shooting level. Seating depth will of course be a little different with the range of BTO I see, but using the middle of the bullet measurements, maybe 0.005" depth will matter less than a difference of 0.005" jump. Maybe I've been lucky and my rounds are more consistent than I think. Would like to know for sure.

Will I see the difference on target? Probably not but I will feel better about it

Glad to see another 22N shooter.

Late edit:
Took a couple loose pocket cases (saved for calibrating annealer), sized and seated one long BTO bullet and one short. Using my homemade case checker got 0.008" difference in the bullets and 0.005" difference in CBTO. The long bullet ended up being in the long cartridge. ???
Will have to wait until I reload a bunch.
Waiting for Midway to go to free shipping again and will get the Hornady comparator set. I do get pretty consistent results with the home made case though.

 

[Taylorbok]

What I've gathered is if your rifle puts up 5 groups of 3 shots 3/8" that is not significant sample size you need to shoot some absurd number of rounds into one group to gather a significant amount of data....

 

[kthomas]

What I've gathered is if your rifle puts up 5 groups of 3 shots 3/8" that is not significant sample size you need to shoot some absurd number of rounds into one group to gather a significant amount of data....

Statistics can be a cruel bitch.

 

[MarkyMark007]

The difference between this rifle shooting consistent .1's-.2's and shooting .3's-.4's was only 15 thousandths of seating depth.

this is 15 thousandths of primer seating depth?

and consistent shooting in .1's and .2's with your rifle on bipod and 3 shot groups? man, you can beat a benchrest champions!

 

[brianf]

this is 15 thousandths of primer seating depth?

and consistent shooting in .1's and .2's with your rifle on bipod and 3 shot groups? man, you can beat a benchrest champions!

not saying who can and cant shoot... as i shoot like crap now because of limited time

true consistent accuracy / true accuracy testing cannot be had off bipod and light bag

if not using a lenzi, seb or alike front rest and a proper very heavy rear bag or a mounted rifle cradle with recoil absorption...all claims about consistent accuracy below .2-.25" and the changes to precision from different variables are not valid over time.

short strings and particular days, there may be a trend

but shoot a few 20 shot strings several days in a row, calling each shot and recording POA POI... thats when real data pertaining to variables starts showing up

just the way it goes

 

[straightshooter1]

Thanks.
Agree, OAL is almost worthless. I will, in a couple days, load another batch and check CBTO out of the seating die to see if the BTO makes any difference in CBTO. I hadn't been checking that. Getting a consistent JUMP might make a little difference at my shooting level. Seating depth will of course be a little different with the range of BTO I see, but using the middle of the bullet measurements, maybe 0.005" depth will matter less than a difference of 0.005" jump. Maybe I've been lucky and my rounds are more consistent than I think. Would like to know for sure.

Will I see the difference on target? Probably not but I will feel better about it

Glad to see another 22N shooter.

Late edit:
Took a couple loose pocket cases (saved for calibrating annealer), sized and seated one long BTO bullet and one short. Using my homemade case checker got 0.008" difference in the bullets and 0.005" difference in CBTO. The long bullet ended up being in the long cartridge. ???
Will have to wait until I reload a bunch.
Waiting for Midway to go to free shipping again and will get the Hornady comparator set. I do get pretty consistent results with the home made case though.

Difference in BTO is different from CBTO in that when you seat a bullet the seating stem is not contacting the same place on the ogive as the comparator. There are variances between the BTO, as measured with a comparator, and the contact point for the seating stem. That variation will result in respective variation in seating depths and CBTO's. To get consistent "seating depths", the distance from the bullet's base to the contact point of the seating stem needs to be consistent, and since jump really isn't all that important as seating depth, CBTO is not anything to focus on except for a starting point in relation to the lands.

Because of having consistent seating depth is so important, I sort my bullets from base to my seating stems contact point using an appropriate comparator, which of course has a much smaller diameter than what's normally used for BTO's. With my Berger 140 Hybrids, I find I only get a variation of ~.001" in each box of 500 of the same lot. After measuring about 50 of them, I stopped as I couldn't find any more variation than that as I selected samples everywhere from the bottom the box to the edges and corners to see if there was uniformity of the whole lot. As consistent as each lot of my Berger's are, going from on lot to another of these 140 Hybrids, I've got a .010 difference between two lots. This means I'll have to make an adjustment in my seating die by .010" when going to the other lot to maintain the same "seating depth". I focus on seating depth and ignore jump as the barrel's throat erodes.

Since I've been sorting this way, I've seen an improvement in my chrono SD's and ES's when using projectiles that have a lot of variance in that distance on the ogive from base to seating stem contact point. And that improvement has shown up on paper as well. . . though I can't say it's a dramatic improvement.

 

[Rocketvapor]

I understand and agree with most of that.
I read somewhere that Berger packages in-line, a box will come off the same machine, the next box maybe another run.
One of the 100 bullet boxes were almost all long, one box almost all short, working through the 1000 bullet box almost all measure in the middle.
Maybe the middle will be for 600yd practice and matches. I could open up the length range of the middle group and capture a higher percentage in that group.
The part I question is that jump doesn't matter (much). Guess all those that set for a particular jump are missing the boat.
At any rate, my precision reloading hasn't been all that precise.
I was setting the seating stem for an OAL based on my Touch dummy. That based my reloads to OAL. Not good.
From now on I'll base off of CBTO of the dummy (one for each barrel). My old barrel and the wife's somewhat new barrel have quite a bit of different in touch length.
I will measure some of the long and short bullets with the seating stem and see how those lengths come out.
I still think the pointy end (where the seating stem hits) isn't as consistent as many believe.
Issue might be somewhat self sorting. The long bullet did give a longer CBTO than a short one (sample size of one each )

 

[straightshooter1]

I understand and agree with most of that.
I read somewhere that Berger packages in-line, a box will come off the same machine, the next box maybe another run.
One of the 100 bullet boxes were almost all long, one box almost all short, working through the 1000 bullet box almost all measure in the middle.
Maybe the middle will be for 600yd practice and matches. I could open up the length range of the middle group and capture a higher percentage in that group.
The part I question is that jump doesn't matter (much). Guess all those that set for a particular jump are missing the boat.
At any rate, my precision reloading hasn't been all that precise.
I was setting the seating stem for an OAL based on my Touch dummy. That based my reloads to OAL. Not good.
From now on I'll base off of CBTO of the dummy (one for each barrel). My old barrel and the wife's somewhat new barrel have quite a bit of different in touch length.
I will measure some of the long and short bullets with the seating stem and see how those lengths come out.
I still think the pointy end (where the seating stem hits) isn't as consistent as many believe.
Issue might be somewhat self sorting. The long bullet did give a longer CBTO than a short one (sample size of one each )

Yes. If they set for a particular jump, then they'll have to adjust and chase the lands as the throat erodes. I've been there and done that because that's what I also saw when I started precision reloading where so many in this forum advocate or emphasize with how far they are from the lands. After hearing about competitive shooters who often don't change their seating depths for the life of their barrels with all that throat erosion, I finally tested it myself with my .308. After .033" throat erosion from 2000+ rounds, keeping my seating depth constant, my groups stayed good. Before, when I was chasing the lands, I found I was taking my loads out of tune making it difficult to keep my groups tight as I had to use a lot of components just to get back in tune. You don't have to take my word or anyone else's about this as you can test this yourself and let the numbers convince you one way or the other . . . as I did.

 

[Pharmseller]

I have waaaaay less experience than most of you but I use the Berger method and it works for me.

The only difference in these loads is OAL.






P

 

[MakeSawdust]

You must have a hell of a time chasing lands.

The jump doesn't matter. Usually a seating depth that shoots lights out will do so until the barrel starts slowing down.

 

[AutoBolt308]

This is my data with factory 308 Remington Core-Lokt Tipped through a Franchi 22” with 2 different CBTO depths at 100. Hornady comparitor measured chamber 2.243”

 

[Yondering]

What I've gathered is if your rifle puts up 5 groups of 3 shots 3/8" that is not significant sample size you need to shoot some absurd number of rounds into one group to gather a significant amount of data....

If those 5 groups of 3 shots each are really as significant as you think - why not shoot them all into the same target, one 15 round group? If the significance is what you think, the group size won't change, right? It'll still be 3/8"?

Except it won't. Your group size will be something much larger, due to the varying location of those individual 3-round groups, and also a much more realistic representation of your rifle's ability to put a round exactly where you want it. Now instead of 15 rounds, try stacking 30+ rounds in the same target for even better data. And of course, look at mean radius rather than group size (which is just extreme spread of the two worst shots, ignoring the rest) for a better representation of what the rifle is capable of with that load.

I've noticed a lot of people shooting 3 round groups are considering group size only, and ignoring how the position of the group moves around on the target. Overlay a bunch of those groups on the same target and it tells a very different story. IMO the only reason to put a bunch of small round count groups on different targets, rather than all on one (for the purposes of testing, not competition), is to make it look like your group sizes are mostly smaller.

 

[Rocketvapor]

Eventually you will see this big hole with fliers out around it

One of the few times all shots were the same load. Not my never ending load development.

 

[1bamashooter]

Curious how the test was flawed? Or how someone might think it’s flawed? (This is a genuine question)

You can't just throw a tuner on a rifle and expect it to turn a 1in rifle into a .2 in rifle. A tuner was designed to keep your rifle in tune when conditions change. You still have to work up a load and get a good seating depth but that tuner will help tune that load even farther. Look up F Class John on YouTube or go over to accurate shooter there is a thread with plenty on information on why it was flawed even from tuner manufacturers

 

[kthomas]

You can't just throw a tuner on a rifle and expect it to turn a 1in rifle into a .2 in rifle. A tuner was designed to keep your rifle in tune when conditions change. You still have to work up a load and get a good seating depth but that tuner will help tune that load even farther. Look up F Class John on YouTube or go over to accurate shooter there is a thread with plenty on information on why it was flawed even from tuner manufacturers

When PRS and adjacent disciplines started using tuners, they did so in a way that no other discipline uses them for. Despite arguing that tuners have been used for decades in other disciplines to justify the use.

F-class and BR disciplines do not use tuners to shrink groups. They use them to "stay in the node" as environmental conditions change. And if you spend any time on any forums where BR and F-Class shooters hang out, you'll see that even they don't agree on how tuners are used. I even saw a big argument between a major tuner manufacturer and a world record setting BR shooter on how that specific tuner should be used. That's pretty telling.

I don't think there's any compelling evidence in the centerfire world that shows that tuners shrink groups. And F-Class and BR shooters certainly don't use tuners for that specific purpose.

 

[timintx]

It has not been in my experience that .004-005" changes in "jump" has had any effect. In fact, I've gone as much as .033" change in jump (due to throat erosion after 2k rounds fired in my .308) and saw very little change where I continued to get nice small groups as when I started, keeping the same seating depth all that time. When I change seating depth that much, I do see changes in velocities and POI's and shapes of the groups.

I have heard that as well, I have done variations of seating depth many hundreds of times over the years but I chrono every shot all of the time to monitor for velocity pattern spikes and drops and to relate velocity to every shot, but still find that some guns and rounds are different. I suspect this is due to the efficiency of the round and friction coefficient patterns within a particular barrel can help to stabilize velocity patterns so that seating depth is less effecting. The main point is seating depth matters no matter how you do it and it does change things . I got an email from a Spanish shooter many years ago. He was going to the world championships and asked if he should re set his seating depth or leave it alone , he had 1000+ rounds on it and was still shooting decent on the original seating depth. I told him hell yes put it back to the jump it was at before it darn sure will not hurt. He won the world championships and I was very relieved to say the least.

timintx

 

[MarkyMark007]

I've noticed a lot of people shooting 3 round groups are considering group size only, and ignoring how the position of the group moves around on the target.

THIS!

all time the same shit: small 3 shot groups moving around of POA...

 

[timintx]

THIS!

all time the same shit: small 3 shot groups moving around of POA...

Do you really think that anyone considers what they put up here absolute? I like others will keep testing at that depth to confirm what preliminary tests show . We just don’t stop and call it good , we keep confirming and keep confirming until we have confidence in our settings . That’s how the civilian world works so get over it .

timintx