Best way to measure neck tension?

[Bill Norris]

What if you measure the neck diameter of a loaded round and then pulled the bullet and then measure the diameter of the neck to see what the neck diameter is without the bullet.........wouldn't the difference be the true neck tension??.........Just a thought.

I think spring back of the brass causes this not to be accurate.

 

[Jerry Wick]

What if you measure the neck diameter of a loaded round and then pulled the bullet and then measure the diameter of the neck to see what the neck diameter is without the bullet.........wouldn't the difference be the true neck tension??.........Just a thought.

Actually, just the opposite.

Measure the neck of a sized piece of brass(with a micrometer, not just dial calipers). Then seat your bullet and remeasure the neck. The difference is how many thousands of neck tension you have.

 

[gpoldblue]

I think spring back of the brass causes this not to be accurate.

Actually, just the opposite.

Measure the neck of a sized piece of brass(with a micrometer, not just dial calipers). Then seat your bullet and remeasure the neck. The difference is how many thousands of neck tension you have.

When you pull the bullet,does the neck diameter then measure the same as before you seated the bullet?

 

[Jerry Wick]

When you pull the bullet,does the neck diameter then measure the same as before you seated the bullet?

No, when you seat a bullet, it will stretch the neck. When you pull the bullet it may spring back a little, but not to the original sized diameter.

 

[ELR LVR]

No, when you seat a bullet, it will stretch the neck. When you pull the bullet it may spring back a little, but not to the original sized diameter.

Do you find it strange that:
No matter the dia they were to begin with before seating a bullet
They are all the same after the bullet is pulled

 

[Jerry Wick]

Do you find it strange that:
No matter the dia they were to begin with before seating a bullet
They are all the same after the bullet is pulled

I've never needed to pull a whole bunch of bullets, but I guess that would mean you have very consistent necks(brass hardness).

 

[Webster]

Curious what the best way to measure neck tension or neck inner diameter? I want to measure the neck ID after they have been sizer and mandrel. Is the best way to do so using pin gauges ?

For loading “match” ammo are you guys measuring each piece prior to bullet seating ?

What's the rifle used for. What size groups do you need?

 

[Webster]

I think spring back of the brass causes this not to be accurate.

What we call tension is not the force gripping the bullet. It's the difference between 2 measurements. A lot of assumptions. It doesn't consider surface smoothness, chemical deposits, lubrication, neck hardness variation even if they are annealed. It's an attempt to make them all the same with unknown variation. I guess it works. One of Erik Cortina's video's shows a large variation in measured seating pressure with well prepared ammo? If you get real fussy your going to have to toss a lot of cases in the trash.

What do you do if you process and sort the cases with pin gauges and they all meet your spec. Then you fire them anneal with AMPS and size them according to your procedure and some don't pass the pin gauge test. Do you toss them. Does the fact that some of the cases don't pass the pin gauge test the second time mean the whole procedure is witchcraft and meaningless?

 

[Fire Dog]

What we call tension is not the force gripping the bullet. It's the difference between 2 measurements. A lot of assumptions. It doesn't consider surface smoothness, chemical deposits, lubrication, neck hardness variation even if they are annealed. It's an attempt to make them all the same with unknown variation. I guess it works. One of Erik Cortina's video's shows a large variation in measured seating pressure with well prepared ammo? If you get real fussy your going to have to toss a lot of cases in the trash.

What do you do if you process and sort the cases with pin gauges and they all meet your spec. Then you fire them anneal with AMPS and size them according to your procedure and some don't pass the pin gauge test. Do you toss them. Does the fact that some of the cases don't pass the pin gauge test the second time mean the whole procedure is witchcraft and meaningless?

Pretty much… If you are watching EC video there is one with FC John at EC’s place while he is loading and he uses an AMP Press to measure the force applied to @ round and that I imagine is the critical indicator of how much neck tension is involved with each round… After all, there seems to be a lot of “Hand Wringing” anxiety about this subject and I suspect that most folks will have other issues that influence what happens down range…
If it is good enough for EC and FC John that are at or near the top of the game it is good for the bulk of us here on the forum.
Without the cost of the AMP Press you can add a force gage to you arbour press to get a reading relating to your neck tension.

 

[Chaotik]

Seating force reflects the friction in the neck, and is a measurement of that. It does not directly reflect the "grip" or tension on a static bullet in the neck. There is no commercially available method or tool to measure the hoop tension of the neck.

 

[Fire Dog]

Seating force reflects the friction in the neck, and is a measurement of that. It does not directly reflect the "grip" or tension on a static bullet in the neck. There is no commercially available method or tool to measure the hoop tension of the neck.

Yes, you are right…
I mandrel the necks to {as near as I can measure} 0.0015” grip/tension,
use a thin wipe of my homemade Neo Lube #2 and I seat with a wilson seater and a K&M arbour press.
Since starting to use a bit of neck lube I can tell that the seating is easier and more consistent.
On Target there seems to have been an improvement in accuracy as well.
Just slightly, but, HEY! every bit helps….

 

[searcher]

My method isn't very scientific, though does require good assortment of bushings. I first size a case with a bushing I know to likely be a bit too large to effectively hold a bullet, which I can pull out with my fingers. Then I go a bushing smaller and retest as to whether I can pull it out with my fingers. Once I am to a point where I cannot pull a bullet out, I use choose a bushing .001" smaller than that to use for my load development (though if semi-auto gun I'll go .002" smaller). When I go to tune a load with the powder I have chosen, at the charge that shows best on paper, I'll fire a group of five starting with the bushing I used for load development, then another group with .001" smaller bushing, then another five shots with yet another .001 smaller bushing. I tend to find that I get my best results with one of the first two - though there are a few loads I found like the heavier tension - usually due to the powder choice. The faster the powder burn - the lighter the tension I usually use. I used to use a force-measuring press, but found I get just as good, if not better results doing it this way. Also, when settling on that first bushing for load development, I consider how long the bullet is. If it is a short varmint bullet (say a 40 grain in a .223 which doesn't extend all the way to the neck juncture), I'll go another .001" smaller - especially in a semi-auto.

 

[mac86951]

Seating force is a good way to gauge neck tension; however, friction may skew the results, as long as you're keeping your cases consistent, the data is good. Graphite dry lube in the necks is my choice to attempt to control this.

I've always gone with the old school method, pin gauges for ID and a tube mic for wall thickness, then mix for OD after seating. In fact, im more lazy and just do wall thickness using a ball mic and then calipers for OD before and after seating. This method assumes brass spring back is consistent, which depends on your brass lifetime and anneal process.

Id recommend that you try both if you can and see what works better for you on target.

-Mac

 

[SilentShooter]

What's the rifle used for. What size groups do you need?

I shoot PRS. My goal is under 1/2” at 100.. I’m shooting 6Dasher.

 

[SilentShooter]

If you are trying to gage the ID of the neck after your brass prep, why not just use the other mandrels?

This of course assumes you have a spread of mandrels above and below the ones you end up using.

When starting out, it is not unusual for someone to only have one bushing and one mandrel, but when you are dedicated to a caliber and spend enough time that brass of different types passes through your hands, you will inevitably have all the pins and all bushings that cover the possibilities with brass thickness and condition. Those mandrels come in fine enough increments to be used as a pin gage.

An actual set of inspection pin gages is also a handy thing to have around the household, but I admit not everyone is into that sort of work.

When/if you take the next steps, you may end up with the ability to measure your seating force and you end up correlating the neck prep, hardness state, cleaning, and lube, etc. to those seating force results.

As far as asking advice on open reloading forums, it is best to narrow down what kind of "match" ammo you are discussing. It can vary from large quantities of pre loaded ammo as in highpower or F-class, all the way down to ammo that is loaded on the spot as in BR. Those contexts drive important details, some of which are different enough to make a big difference in the answers you will get. YMMV

Thanks for the knowledge bomb. I shoot PRS. I have been reloading range/target ammo for years but recently made the investment of better equipment to produce more consistent ammo.
My reasoning behind this post was me brainstorming how can I better my SD/ES. I’m shooting 6Dasher. The universe says Varget is the best powder for that caliber. It’s also told me 2850fps is a sweet spot for it as well. I played around with different charge weights but the accuracy for me didn’t change much. I was however curious why ES/SD was high. Now admittedly I never really thought about testing different bushing/mandrel for neck tension. The universe said .003 so I just stuck with that. I just thought maybe there is too much variation with my brass with the neck tension. Maybe that’s why the ES/SD is higher. So should I measure each piece? I do use an inline bullet seater and arbor press but maybe it’s my lack of experience it all fells that same. I thought about testing different seating depth but the universe tells me neck tension will have more effect.
Anyway lots of good info so far and it’s a lot for me to think about and test so appreciate everyone post

 

[muleystalker]

Don't worry so much about ES/SD, load what shoots good on the target. Do a seating depth test, it will probably benefit you more.

 

[RegionRat]

So should I measure each piece? I do use an inline bullet seater and arbor press but maybe it’s my lack of experience it all fells that same. I thought about testing different seating depth but the universe tells me neck tension will have more effect.

The minute someone suggests you do or don't measure everything, someone else will come along and dump on the comments.
I will suggest you take a methodical and careful approach early in your career, and then once you have seen what causes problems in your performance you will likely be able to cut back on some details.

There is a vast difference in what you can get away with in short range testing, versus at distance where the vertical shot fall is affected by the SD/ES.

One person can say just look at the groups, another will focus on ES/SD independently.

I say, if the system can group well at distance, by definition the ES/SD is good. With that said, it doesn't mean you will see sloppy ES/SD giving competitive target performance at say 600 yards or more.

 

[Kracken McGraw]

https://www.midwayusa.com/product/1024875371?pid=158545
I was looking at Forster products and noticed these tools.

 

[Webster]

The minute someone suggests you do or don't measure everything, someone else will come along and dump on the comments.
I will suggest you take a methodical and careful approach early in your career, and then once you have seen what causes problems in your performance you will likely be able to cut back on some details.

There is a vast difference in what you can get away with in short range testing, versus at distance where the vertical shot fall is affected by the SD/ES.

One person can say just look at the groups, another will focus on ES/SD independently.

I say, if the system can group well at distance, by definition the ES/SD is good. With that said, it doesn't mean you will see sloppy ES/SD giving competitive target performance at say 600 yards or more.

I don't think pin gauges are supposed to be used on textured surfaces. If you had a perfect dimension neck with 1 high spot 0.001" I would think a pin gauge would be a fail.