Sorting rounds by times brass was shot or PSI?

[INTJ]

I had loaded some rounds to test for a 600 yard match. Bullets usually seat with about 35-40 psi on the hydropress. One of the rounds seated with less than 10 psi - you could move the bullet a bit if you pushed/pulled on it. I colored this one outlier with a red sharpie.

Day before the match @ 600 yard practice/sight-in - shot the 4 seated @ 35-40psi. Then shot the red-marked bullet last.

View attachment 1218652


Yeah I know the sample size is too small to draw any conclusions.... YMMV

I think there needs to be a larger difference in PSI readings, like you and I have discussed. I am not sure 20 PSI makes much difference, but I'll bet a 50 PSI difference would......though not as much as a REAL dropped shot.........

 

[David Christian]

I think there needs to be a larger difference in PSI readings, like you and I have discussed. I am not sure 20 PSI makes much difference, but I'll bet a 50 PSI difference would......though not as much as a REAL dropped shot.........

This would be easy to test. Just use different bushing sizes and/or gage pins to create a wide extreme and then shoot them blind. 10 shots at each extreme would at least give you a tell tale sign if it really matters.

If I think about my reloading process, I would wager that annealing after each firing along with chamfering with a Giraud are the two main ways that my seating pressures are virtually identical across hundreds of rounds. It took a great deal of fine tuning to get to this result, but I didn’t want to chase my tail sorting loaded rounds with potentially uncertain results, so I chased the underlying variables up my reloading process.

 

[CA_Shooter]

This would be easy to test. Just use different bushing sizes and/or gage pins to create a wide extreme and then shoot them blind. 10 shots at each extreme would at least give you a tell tale sign if it really matters.

If I think about my reloading process, I would wager that annealing after each firing along with chamfering with a Giraud are the two main ways that my seating pressures are virtually identical across hundreds of rounds. It took a great deal of fine tuning to get to this result, but I didn’t want to chase my tail sorting loaded rounds with potentially uncertain results, so I chased the underlying variables up my reloading process.

Turns out i didn't have to mix brass to get enough rounds done. Out of 80 rounds shot twice:

63 were between 70-80 PSI
8 were between 55-68 PSI
1 was at 95 (my first...I think I didn't warm it up)
8 were at 81-85

 

[LRPV]

Many have proven neck tension/interference fit whatever you call it, is a definite tuning tool. What hasn’t been proven, as far as I know, is that seating force means Dick. Shortly after buying my first seating force press I proved to myself that a plastic brush in a drill ran one time, 2 time, 3 times or different durations of each had a significant effect on seating force with no other changes. Personally have found anything under about 18 on my K&M is suspect and won’t hold its position. Other than that from like 25-50 will shoot together. This is jamming bullets .006-.012 and no, I don’t have that much variation in my match rounds but any batch in that window will shoot well. I will record seating force each time I load more for comparison sake than anything else. I anneal every time but still sometimes need to use a different bushing one way or the other to stay on top of the tune.

Side note, I’ve ran 21st century side X side with K&M and they both do the same thing. It’s a personal preference thing on which I chose to keep. I personally like the K&M feel better.
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[INTJ]

Many have proven neck tension/interference fit whatever you call it, is a definite tuning tool. What hasn’t been proven, as far as I know, is that seating force means Dick. Shortly after buying my first seating force press I proved to myself that a plastic brush in a drill ran one time, 2 time, 3 times or different durations of each had a significant effect on seating force with no other changes. Personally have found anything under about 18 on my K&M is suspect and won’t hold its position. Other than that from like 25-50 will shoot together. This is jamming bullets .006-.012 and no, I don’t have that much variation in my match rounds but any batch in that window will shoot well. I will record seating force each time I load more for comparison sake than anything else. I anneal every time but still sometimes need to use a different bushing one way or the other to stay on top of the tune.

Side note, I’ve ran 21st century side X side with K&M and they both do the same thing. It’s a personal preference thing on which I chose to keep. I personally like the K&M feel better.
‍

Seating force variations can cause changes in seating depth. It can be caused by less neck tension, lube in the case mouth, or variations in brass spring back. I measure every round after seating bullets so I catch it if it happens.

We know variations in seating depth can affect the tune, but I think as big of a factor is the variations in spring back. Sorting by PSI can help identify such cases.

 

[mikecr]

The thing is; seating force is so heavily tied to seating friction as to be near meaningless to neck tension (which is what matters). The only condition in which a correlation between seating force and neck tension can be seen(clearly) is when seating friction is absolutely normalized.
This is where variances in lubes, and frictional changes with frequent annealing, etc., mess up the measure.

At least understand that seating friction (aka pull force), in itself, holds no internal ballistic significance whatsoever. You could test it and see for yourself what newbieshooter pictured.
And know also that we do not currently have a method to measure actual neck tension (which really is significant).
It's important to objectively think about this when considering sorting by seating friction.
Could be the very worst thing to do.

I use an instrumented mandrel die with a built in transducer feeding a meter(it's an electronic system).
Mandrel expansion is my 'Pre-seating' operation, which I always do, and measuring at this stage affords me the ability to affect the outcome(change neck tension to match).
I have confidence in my correlation [force to tension] because I control all matters of friction moreso than most reloaders. This took efforts on my part(decades of direct experience) to learn what works and doesn't work, and I suspect that you're at an early stage here.

So I would NOT recommend sorting by your seating forces -YET.
I WOULD recommend managing cases at same sizing cycles.
When the first primer pocket loosens, the majority should just the same, rake them into a trash can and begin with a new batch prepped and ready for this.

As far as managing same neck tension, minimally sizing helps the most. Annealing helps,, provided your load likes lower neck tension. If your load likes higher tension, and you want it consistent, then you're back to minimal sizing. The only way around that is to go small underbore cartridge, running extreme pressure loads, with bullets jammed or necks sized beyond seated bullet bearing (to raise starting pressure).

 

[Ccrider]

Why wouldn’t cleaning the necks normalize friction?

 

[CA_Shooter]

The thing is; seating force is so heavily tied to seating friction as to be near meaningless to neck tension (which is what matters). The only condition in which a correlation between seating force and neck tension can be seen(clearly) is when seating friction is absolutely normalized.
This is where variances in lubes, and frictional changes with frequent annealing, etc., mess up the measure.

At least understand that seating friction (aka pull force), in itself, holds no internal ballistic significance whatsoever. You could test it and see for yourself what newbieshooter pictured.
And know also that we do not currently have a method to measure actual neck tension (which really is significant).
It's important to objectively think about this when considering sorting by seating friction.
Could be the very worst thing to do.

I use an instrumented mandrel die with a built in transducer feeding a meter(it's an electronic system).
Mandrel expansion is my 'Pre-seating' operation, which I always do, and measuring at this stage affords me the ability to affect the outcome(change neck tension to match).
I have confidence in my correlation [force to tension] because I control all matters of friction moreso than most reloaders. This took efforts on my part(decades of direct experience) to learn what works and doesn't work, and I suspect that you're at an early stage here.

So I would NOT recommend sorting by your seating forces -YET.
I WOULD recommend managing cases at same sizing cycles.
When the first primer pocket loosens, the majority should just the same, rake them into a trash can and begin with a new batch prepped and ready for this.

As far as managing same neck tension, minimally sizing helps the most. Annealing helps,, provided your load likes lower neck tension. If your load likes higher tension, and you want it consistent, then you're back to minimal sizing. The only way around that is to go small underbore cartridge, running extreme pressure loads, with bullets jammed or necks sized beyond seated bullet bearing (to raise starting pressure).

I clean my brass with stainless steel media.

I have tried each of the three methods for seating without lube for a .264 bullet

•sizing with a normal RCBS die and not opening the necks with a mandrel: i hit 100 PSI on my arbor press and didn't get close to seating the bullet. Was still hundredths off from seating depth. Stopped there.
•sizing with a normal RCBS die and opening the necks with a .2635 mandrel: consistently hit 90-100 PSI on the arbor press
•sizing with a normal RCBS die and opening the necks with a .2640 mandrel: consistently hit 70-80 PSI on the arbor press with some above and some below

The above was done with the same brass shot the same amount of times. What this tells me is that there is a correlation between internal neck diameter and seating pressure.

This would follow that there is a correlation between seating force and neck tension

 

[INTJ]

The thing is; seating force is so heavily tied to seating friction as to be near meaningless to neck tension (which is what matters). The only condition in which a correlation between seating force and neck tension can be seen(clearly) is when seating friction is absolutely normalized.
This is where variances in lubes, and frictional changes with frequent annealing, etc., mess up the measure.

At least understand that seating friction (aka pull force), in itself, holds no internal ballistic significance whatsoever. You could test it and see for yourself what newbieshooter pictured.
And know also that we do not currently have a method to measure actual neck tension (which really is significant).
It's important to objectively think about this when considering sorting by seating friction.
Could be the very worst thing to do.

I use an instrumented mandrel die with a built in transducer feeding a meter(it's an electronic system).
Mandrel expansion is my 'Pre-seating' operation, which I always do, and measuring at this stage affords me the ability to affect the outcome(change neck tension to match).
I have confidence in my correlation [force to tension] because I control all matters of friction moreso than most reloaders. This took efforts on my part(decades of direct experience) to learn what works and doesn't work, and I suspect that you're at an early stage here.

So I would NOT recommend sorting by your seating forces -YET.
I WOULD recommend managing cases at same sizing cycles.
When the first primer pocket loosens, the majority should just the same, rake them into a trash can and begin with a new batch prepped and ready for this.

As far as managing same neck tension, minimally sizing helps the most. Annealing helps,, provided your load likes lower neck tension. If your load likes higher tension, and you want it consistent, then you're back to minimal sizing. The only way around that is to go small underbore cartridge, running extreme pressure loads, with bullets jammed or necks sized beyond seated bullet bearing (to raise starting pressure).

It's not hard to normalize seating friction. Using my normal case prep methods
I get very consistent seating PSI. Usually within 10 PSI. Like I said earlier, I think it takes a larger difference in PSI seating pressure to show up in the target.

My very last step in case prep, after the cases are primed and right before I charge with powder, I brush each case neck with a nylon brush. Doing that usually gives me 20 PSI with very little variation. If I don't brush the case neck, I'll get 35-40 PSI. That is purely a friction difference, but it also frequently results in a bullet that is seated .001" long.

When I have brushed all the case necks like normal, and I get a case that is 10 or 15 PSI higher than the rest, it becomes a sighter. There is differently something different about that case, and I am not willing to take a chance on it.

That said, these fine point of loading for LRBR are easily overwhelmed by conditions at 600 and especially 1000 yds. Much of what we do only matters in very good conditions. Sorting by PSI is fast and easy to do. I don't worry about seating PSI and neck tension on my other rifles.

 

[mikecr]

I clean my brass with stainless steel media.

there is a correlation between internal neck diameter and seating pressure.
This would follow that there is a correlation between seating force and neck tension

Taking necks to squeaky clean does normalize friction, while leaving that friction too high to correlate with neck tension. It's bad for this endeavor, and as you described, causes excess seating forces.
A flip side action just as bad is to wet lube the inside of necks. This dropping seating forces too low to get a good reading on.
That there is correlation between neck interference and seating forces needed to overcome that interference(re-expand) should be easy enough for most to picture. That this indicates anything directly about neck tension is usually incorrect.
Neck tension IS NOT neck interference.

My very last step in case prep, after the cases are primed and right before I charge with powder, I brush each case neck with a nylon brush. Doing that usually gives me 20 PSI with very little variation. If I don't brush the case neck, I'll get 35-40 PSI. That is purely a friction difference, but it also frequently results in a bullet that is seated .001" long.

This is best, with expected results.
There is no better neck lube than the normal carbon residue, surface freshened with a nylon brush.
You can also see across a chronograph that the different seating forces you're seeing here do not actually affect load results. This, because they're purely frictional changes instead of neck tension changes.
It all goes back to what neck tension is and is not.
It affects seating results due to varying seater plug wedging on bullet noses. More force, more wedging, often less consistently (against normal ogive radius variances).