Neck Tension questions

[WyleWD]

Keep in mind that some of your neck tension will be the result of how well and consistently you turn your necks, and how many firings you have on your brass.

Personally I like to have .003 to .005 tension on mine, but always let the rifle tell me what it likes. So my long winded answer is do the testing as others have suggested and let the rifle do the talking. You'll be glad that you did. WD

 

[shoot4fun]

Over time my experience has shown not so much issue with pressure change but with accuracy. More neck tension often increases run out but, more importantly, I have found it to bring on that nasty vertical stringing that is a real group killer.

 

[dmoran]

Can and will do , thanks. Yes lots of good info here, really helpful.

Any problems if I had gotten a bunch of brass neck sized, decide I want to use tighter tension then run the brass through a tighter bushing?

Not in my experience... run them through again.
Have done it myself a time or two.
Donovan

 

[dkhunt14]

Over time my experience has shown not so much issue with pressure change but with accuracy. More neck tension often increases run out but, more importantly, I have found it to bring on that nasty vertical stringing that is a real group killer.

I believe you have something else going on. I have ran as much as .009 and never saw it cause run out. It usually is more accurate vertically. I also never seen it damage a bullet but I shine mine to bare brass. The thing is, we shoot 5 and 10 shot groups all the time in practice and shoots at a 1000 yards. We see what works and what doesn't, we get every target back. Not just a score on a target we didn't get to see. I can see and measure the vertical and the tight knots when they appear. Matt

 

[LHSmith]

FWIW-Input from a short range Benchrest competitor- NT is dependent on the powder used.....of the popular powders in the 6 PPC - these values are typically the norm: T-322, H-322 likes light NT .002/003" , LT-32, XBR-8208 likes moderate NT- .003/.004", and the most used powder N-133 likes heavy NT ~.005". These numbers work for neck turned brass from .262 to .269 chambers. Shooting the 6 PPC ,we have the luxury of having carbide bushings available in 1/2 thou sizes....and with a good tuned load you can see the difference 0.0005" NT makes @100 yds.

 

[bugman]

Very good info on this thread.

The only thing I can add is that the choice of powder (and burn rate) can also be part of the reason for the big differences in the neck tensions mentioned in this thread. Changing powder brands, and even just lots of the same powder, might require you to re-test neck tension for your favorite recipe.

Jack

**apologies for saying basically the same thing as LHSmih. I must have been typing this when he posted **

 

[fastarget]

FWIW-Input from a short range Benchrest competitor- NT is dependent on the powder used.....of the popular powders in the 6 PPC - these values are typically the norm: T-322, H-322 likes light NT .002/003" , LT-32, XBR-8208 likes moderate NT- .003/.004", and the most used powder N-133 likes heavy NT ~.005". These numbers work for neck turned brass from .262 to .269 chambers. Shooting the 6 PPC ,we have the luxury of having carbide bushings available in 1/2 thou sizes....and with a good tuned load you can see the difference 0.0005" NT makes @100 yds.

Yes, I have been doing some testing, and shall continue. So far, at 100m, hoping enough thaw occurs this week to go to 3-600.
Interesting about NT and Powder, first time I have read about that relationship, is it related to burn rates, flame propagation?

 

[lawrence97]

Carl, here is a quick test I conducted at 1000 yards for neck tension. It was windy but one neck tension definitely outshines another.
And to stir the pot further, I compared dirty vs clean brass! Tons of info for you in this post and the conclusion is to Test for yourself or you will never know.

 

[Brians356]

How do you chaps determine what the actual IDs of your necks are before seating? (I don't mean decide what ID should be, I mean how you gauge or measure the ID.)

 

[savagedasher]

How do you chaps determine what the actual IDs of your necks are before seating? (I don't mean decide what ID should be, I mean how you gauge or measure the ID.)

Measure the od deduct twice the thickness of the neck . Say the neck is . 012 double that from the total Od . Larry

 

[ireload2]

Those of you that do not have any experience with hand dies might appreciate the differences in seating force if you used them a little with one of the small benchrest type arbor presses. You can actually feel the differences in seating force from one case to the next or .001" larger or smaller neck bushing.
I like to use a tapered neck expander to push the inside corner of the case mouth out enough that it cannot dig into the bullets when seated. This is an added operation unless you use something that approximates a Lyman M die.
You see some brands of flat based that have very little base corner radius. Hornadys sometime have this sharp heel corner.
These bullets are more easily damaged when seated with tighter necks and case mouths with small chamfers. Softer jackets are more easily damaged. I like shooting Nosler Ballistic tips because the impact extruded solid base inherited from the original Nosler Solid Base bullets is harder to damage.

 

[mikecr]

Lotta good & bad info here.
#1 Tension is bullet grip, which is spring back against bullet bearing
#2 Spring back is limited (normal neck spring back range is ~.5-1.5thou against bearing)
#3 Spring back is counter to last action(sizing direction), and some of it continues over time
#4 We currently have no way to measure this directly (seating force does not measure tension)
#5 Actual tension change does affect pressure & MV
Remember these and you can separate notions meaningful and meaningless.

2thou downsizing of necks is sufficient and not overworking.
Practical adjustment of tension is a matter of LENGTH of normal downsizing. If sizing length is within seated bullet bearing, then reducing bushing size past 2thou contributes no more than overworking.
Where sizing more than seated bearing, further downsizing does add tension to the area in contact, but variance increases with this. So frequent annealing is called for there, which defeats the apparent effort to gain tension..

 

[fguffey]

Lotta good & bad info here.
#1 Tension is bullet grip, which is spring back against bullet bearing
#2 Spring back is limited (normal neck spring back range is ~.5-1.5thou against bearing)
#3 Spring back is counter to last action(sizing direction), and some of it continues over time
#4 We currently have no way to measure this directly (seating force does not measure tension)
#5 Actual tension change does affect pressure & MV
Remember these and you can separate notions meaningful and meaningless.

It has always been bullet hold, then came tensions. I am the only one with tension gages; not a problem for me but all my tensions gages are calibrated in pounds even when the gage measured deflection. Those that can not force themselves to say bullet hold are now moving to bullet grip.


Then there are other factors such as the difference between a case with all the bullet hold I can get and a case neck with less bullet hold.


F. Guffey

 

[dkhunt14]

I have seen the same thing TOM. Your right you have to be able to shoot the difference. Matt

 

[Rtheurer]

Good Thread, but I wish those posting would post what the neck THICKNESS for which they are working with. Seems to me ( and I may be wrong here) that some one running .003 Neck tension/hold/grip with necks turned down... to say .010 vs Someone running a no turn brass set up at .014 neck thickness and also running .003 could be a large change in the amount of force it is giving on the bullet and there for the release of bullet. Maybe I am looking at this the wrong way? Seems to me it would matter. But then again what really matters is what ends up on the target no matter what the numbers on the bushing says I guess.

Russel

 

[Mulligan]

Carl, thanks for asking the question.
I have learned a couple of things.
Tom, that picture is a great bit of info.
CW

 

[22BRGUY]

After you turn the necks polish the necks with fine steel-wool, is my advise.
Donovan

I then like to use a strong magnet to attract the steel wool particles

 

[mikecr]

Mikecr,Would you refer to the target I posted on page one. Please explain how sizing more than 2 thousandths is a waste of time. While it may take a rifle capable of shooting the difference, the results are the results. Tom

The purpose of testing is to learn something from results. I don't know what you learned but your picture tells us nothing, as the conditions and results are not defined. It seems merely an abstract.
This discussion began about ~2thou neck tension as a standard, and it appears you didn't test 2thou tension. Or, maybe you did, and didn't bring it into basis to counter any of my rules. You didn't qualify the conditions so that we could understand your sizing at all. Was it partial, FL? Have you considered normal sizing with an adjustment to powder? Seems to me that if you're actually producing any more tension than that provided by normal spring back to bearing, and need this to shoot 'better', your powder load may not be optimum, and/or your seating might be off from best. There is at least that potential so far.

I'll never suggest that testing is a bad approach. But we should accept conclusions when we understand them (when they make sense).

 

[jlow]

Good Thread, but I wish those posting would post what the neck THICKNESS for which they are working with. Seems to me ( and I may be wrong here) that some one running .003 Neck tension/hold/grip with necks turned down... to say .010 vs Someone running a no turn brass set up at .014 neck thickness and also running .003 could be a large change in the amount of force it is giving on the bullet and there for the release of bullet. Maybe I am looking at this the wrong way? Seems to me it would matter. But then again what really matters is what ends up on the target no matter what the numbers on the bushing says I guess.

Russel

Agreed! That and potential difference in spring back due to differences in degree of work hardening/annealing would also potentially make a significant difference on the amount of force on the bullet. I can imagine running a neck through a bushing and the spring back not giving the sizing on the bushing. One can of course bypass this by measuring the OD and minus the two neck thickness to get a "neck tension" number, but now when you seat the bullet, two necks with the same ID will still give different grip if one has more spring back than say a softer neck. So from that standpoint, that "neck tension" number leaves a lot of things which can have a significant effect unstated.

 

[dmoran]

The purpose of testing is to learn something from results. I don't know what you learned but your picture tells us nothing, as the conditions and results are not defined. It seems merely an abstract.
This discussion began about ~2thou neck tension as a standard, and it appears you didn't test 2thou tension. Or, maybe you did, and didn't bring it into basis to counter any of my rules. You didn't qualify the conditions so that we could understand your sizing at all. Was it partial, FL? Have you considered normal sizing with an adjustment to powder? Seems to me that if you're actually producing any more tension than that provided by normal spring back to bearing, and need this to shoot 'better', your powder load may not be optimum, and/or your seating might be off from best. There is at least that potential so far.

I'll never suggest that testing is a bad approach. But we should accept conclusions when we understand them (when they make sense).

Hey Tom -
According to Mike, your powder charge wasn't optimal and your seating is off.. lol
Just think, when you get them nailed down, what your 1k groups might measure !.!.!
What does that 0.0047" tension group measure? (I'm guessing about .2-MOA)

Mike -
If Tom's results don't make sense to ya, I can't help ya....
But I would like to see your results, since all I have seen is your own written theorem's.

Donovan