Seating force variance

[JFrank]

I should spend more time at the bench. You know instead of this friggin desk...Mike

God Bless ya”

 

[mikecr]

Do you group by seating force? If so, what would be the max/min poundage that you deviate from?

I don't use a K&M or bullets for force measure.

This is a comparison, only indicative of neck tension(with all else normalized), and not a direct measure.
I happen to use a Sinclair mandrel die in which I've installed a load cell. My measure is of pre-seating forces, which I can adjust to matching -prior to seating actual bullets.
These numbers are dimensionless, not in pounds, and pounds in particular have no meaning here. All you need is to be 'on scale' (any scale) for the range of seating forces presented and compared.

What your numbers mean is a local matter, in no way correlating with anybody else (including those also using a K&M). Your necks are not the same hardness, your sizing not to the same interference fit, your seating frictions are different.
So when you wonder 'what do my numbers mean?',, they're your numbers, it's for you to explore.
It's been suggested that you group & shoot em. That's a logical next step.

 

[JFASH]

I also use a sinclair expander prior to seating. When i said pounds, i should've said "dial setting" on the indicator. The force varies slightly. I wonder if neck turning would make the numbers more uniform?
Thanks
Joe

 

[ratbuster]

Once when loading a few hundred 20 practical varmint rounds I decided to do a test to determine what effect seating force had on velocity. Of that lot I selected 5 each cartridges of heaviest and lightest seating force. Those 10 cartridges were the most extreme outliers, that is the 5 lightest were much much lighter than the 5 heaviest. The shocker was the velocities from the two groups were super close together and I saw no difference in group size either. Totally unexpected. Now I pay no attention to seating force.

 

[jds holler]

Once when loading a few hundred 20 practical varmint rounds I decided to do a test to determine what effect seating force had on velocity. Of that lot I selected 5 each cartridges of heaviest and lightest seating force. Those 10 cartridges were the most extreme outliers, that is the 5 lightest were much much lighter than the 5 heaviest. The shocker was the velocities from the two groups were super close together and I saw no difference in group size either. Totally unexpected. Now I pay no attention to seating force.

That^^^ is exactly the kind of info I'm interested in, and need to do for myself. I wonder if jam or distance from jam would make a difference in your results. jd

 

[ratbuster]

That^^^ is exactly the kind of info I'm interested in, and need to do for myself. I wonder if jam or distance from jam would make a difference in your results. jd

JDS

That's something I've not considered. Given there are so many variables when it comes to shooting for precision I imagine there are scenarios where results could be quite different than what I saw with my test.

 

[group therapy]

@Puzzaz01 should chime in and of course the mighty "guffey"

 

[jds holler]

F. Gufffffeeeeeeyyyyy wheeeeerrrrrreeee aaaarrrrrrreeeeee yoooouuuu.

 

[David Christian]

That^^^ is exactly the kind of info I'm interested in, and need to do for myself. I wonder if jam or distance from jam would make a difference in your results. jd

@jds holler, if you find that you have large seating force variations, something is off in your downstream reloading process. Else, a +2 or a +6 change in force could very well be related to your measurement process and in all likelihood means very little related to your results on target and you can ignore. I might focus more time on reading the wind.

 

[OmegaRed]

sub

 

[memilanuk]

Once when loading a few hundred 20 practical varmint rounds I decided to do a test to determine what effect seating force had on velocity. Of that lot I selected 5 each cartridges of heaviest and lightest seating force. Those 10 cartridges were the most extreme outliers, that is the 5 lightest were much much lighter than the 5 heaviest. The shocker was the velocities from the two groups were super close together and I saw no difference in group size either. Totally unexpected. Now I pay no attention to seating force.

Interesting. I had exactly the opposite experience.

Last year the brass I loaded up for FCNC was the same stuff I'd been using all year long, with all the appropriate prep - dry tumble, anneal, size, trim, tumble lube off, brush the necks, apply some Imperial dry neck lube... same schtick I'd been doing. Suddenly had some rounds that felt off, that the seating force was notably lighter, along with a few that were definitely heavier. I disregarded that, and paid for it on target with some very off-call shots (vertical). I meant to get around to sorting that out, but between one thing and another, it didn't happen. Still have ~100rds of that ammo loaded up, and that barrel around here somewhere, but never got around to tracking down the why or wherefore.

Then started loading ammo for the SWN this year. Different brass, known-good from 2017 FCWC cycle, no issues during load development. Had an occasional few that were lighter, that I just used for sighter/foulers as I was mostly shooting small batches. Then when I started loading several hundred for the match, I really started noticing it again. I have a hydro seater, but it's not part of my normal regime as the die I use with it is a royal PITA. On the hydro seater, the 'normal' seating force was in the 30-35 range, the 'light' was in the <20 range, and the 'heavy' seating force was >50. Actually the 'heavy' was more like a 'pop' (felt, not audible) at the case mouth, then basically normal seating force. The effects (normal, light, heavy) were enough that I could definitely feel it even on my regular press (550 w/ Forster Ultra BR seater).

This time I was a *little* smarter than last fall. I started taking the ones that seated light (because they were more common, and the ones I thought were the problem) and coloring the tip with a blue sharpie so I could identify them in the box. Later, I decided to start taking the ones that seated heavy and color them red. Figured I had a number of strings with unlimited sighters, and I'd do a little experiment at some point.

So on that Tuesday during squadded practice @ 1k, I got the gun centered up, holding pretty decent waterline with the ammo that had 'normal' seating force. Then I shot 5 of the 'blue' rounds (remember, these were the ones I was expecting to be 'the problem') - right in with the others, indistinguishable from the first group. Hmmm... then I shot 5 of the red tipped ones, and yup, there it is: nice tight group, but a good 1 moa low and .5 moa right, skirting the 9 line, into the 8 @ 4:30. Just for confirmation, I shot 5 more of the 'normal' ones, and bam, right back up into the X-ring.

The good news: I confirmed that there *was* a definite, measurable difference going on, and it wasn't anything to do with the nut behind the trigger.

The bad news: apparently I need to fire the guy loading the ammo

The worse news... I didn't 'wise up' and start marking the 'red' ones until about halfways thru the loading session. So there were one or two boxes that were like Cracker Jacks... a few hidden 'surprises' still lurking in there

Things have been slightly nuts here since that match... probably going to be sometime *next* month before I have a chance to fire off the remaining ammo, and dig into WTF is causing that weird 'pop' on some cases when seating. I checked some of the usual culprits that came to mind (burr inside the case mouth, etc.) at the time and came up with nothing.

 

[Ned Ludd]

Interesting. I had exactly the opposite experience.

Last year the brass I loaded up for FCNC was the same stuff I'd been using all year long, with all the appropriate prep - dry tumble, anneal, size, trim, tumble lube off, brush the necks, apply some Imperial dry neck lube... same schtick I'd been doing. Suddenly had some rounds that felt off, that the seating force was notably lighter, along with a few that were definitely heavier. I disregarded that, and paid for it on target with some very off-call shots (vertical). I meant to get around to sorting that out, but between one thing and another, it didn't happen. Still have ~100rds of that ammo loaded up, and that barrel around here somewhere, but never got around to tracking down the why or wherefore.

Then started loading ammo for the SWN this year. Different brass, known-good from 2017 FCWC cycle, no issues during load development. Had an occasional few that were lighter, that I just used for sighter/foulers as I was mostly shooting small batches. Then when I started loading several hundred for the match, I really started noticing it again. I have a hydro seater, but it's not part of my normal regime as the die I use with it is a royal PITA. On the hydro seater, the 'normal' seating force was in the 30-35 range, the 'light' was in the <20 range, and the 'heavy' seating force was >50. Actually the 'heavy' was more like a 'pop' (felt, not audible) at the case mouth, then basically normal seating force. The effects (normal, light, heavy) were enough that I could definitely feel it even on my regular press (550 w/ Forster Ultra BR seater).

This time I was a *little* smarter than last fall. I started taking the ones that seated light (because they were more common, and the ones I thought were the problem) and coloring the tip with a blue sharpie so I could identify them in the box. Later, I decided to start taking the ones that seated heavy and color them red. Figured I had a number of strings with unlimited sighters, and I'd do a little experiment at some point.

So on that Tuesday during squadded practice @ 1k, I got the gun centered up, holding pretty decent waterline with the ammo that had 'normal' seating force. Then I shot 5 of the 'blue' rounds (remember, these were the ones I was expecting to be 'the problem') - right in with the others, indistinguishable from the first group. Hmmm... then I shot 5 of the red tipped ones, and yup, there it is: nice tight group, but a good 1 moa low and .5 moa right, skirting the 9 line, into the 8 @ 4:30. Just for confirmation, I shot 5 more of the 'normal' ones, and bam, right back up into the X-ring.

The good news: I confirmed that there *was* a definite, measurable difference going on, and it wasn't anything to do with the nut behind the trigger.

The bad news: apparently I need to fire the guy loading the ammo

The worse news... I didn't 'wise up' and start marking the 'red' ones until about halfways thru the loading session. So there were one or two boxes that were like Cracker Jacks... a few hidden 'surprises' still lurking in there

Things have been slightly nuts here since that match... probably going to be sometime *next* month before I have a chance to fire off the remaining ammo, and dig into WTF is causing that weird 'pop' on some cases when seating. I checked some of the usual culprits that came to mind (burr inside the case mouth, etc.) at the time and came up with nothing.

Monte - any chance you might have had the LabRadar turned "on" while you were pulling the trigger on those red and blue tips? It'd be interesting to know whether velocity was changing noticeably and/or in a consistent pattern for those rounds.

 

[memilanuk]

Oh, I agree it would have been *very* interesting... but it was looking like people were going to be pissy about me setting it up on the line, even though it was just 'practice' and not a match.

I'd have to take a closer look at how many of each I have left... like I said, it's been nuts here (packing to move). But I'd like to replicate that little experiment here at home... with my LabRadar, and my ShotMarker e-target. Only 600yds, though.

 

[dcali]

Sometimes I wonder if the differences that some people seem to report with heavy seating force isn’t due to scraping the bullet during the seating operation. When I feel a heavy seat, it’s not usually smooth. It sort of crunches and then goes easier.

 

[paulT]

Sometimes I wonder if the differences that some people seem to report with heavy seating force isn’t due to scraping the bullet during the seating operation. When I feel a heavy seat, it’s not usually smooth. It sort of crunches and then goes easier.

I agree and have also found when neck shamfering using a few passes with a fine vld type neck tool the gauge on my k&m arbor press reading seems to pop when seating however when i use the k&m neck shamfer tool which tends to remove more material the pop upon seating doesnt seem to happen.