Best way to measure neck tension?

[SilentShooter]

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 ?

 

[Mastershot]

Loaded or unloaded ammo. I use loaded ammo and then measure the neck and then use a bushing die to set the right neck tension. I then seat them on my 21st century hydro press in a inline seating die to check pressure.

 

[SilentShooter]

So I want to check cases for uniform neck tension from case to case. After they have been sized and mandrel. Is that not a common practice?

 

[JMayo]

K&m force pack. Not the neck tension but the conformity. If they all start and finish at the same point, gtg, imo

I do not understand a mandrel and a bushing used together. But many do it

 

[SilentShooter]

So better to just measure the force while seating the bullet on my K+M arbor press?

 

[JMayo]

I tested "neck tension" bushings and came up with what shot better.
All mine start seating at 10 & complete at 30 + - with the bushing i use. I'm shooting 108's.

 

[Clancy]

I think that if I were NOT turning and trying to find say 15 perfect cases…. I’d use a ball mic and measure the neck wall in 4 spots. Sort 100 pieces of brass into lots. Should be able to cull the outliers.

If I had 35 or 40 that showed very little variance, I’d cull them yet again by measuring the loaded round over the pressure ring.

Now I’ve probably got about 30 perfect cases to test bushings with.

Then, let’s say this is a 6BR, and I found that a .266 bushing shoots the best….. I’d throw every one of them that didn’t have a crazy variation back in the box and start sizing them with the .266. Use anything crazy (which is gonna be rare if it’s Lapua) as a sighter or fouler.

 

[Straightshooter1]

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 ?

These days, I do use pin gauges to measure the ID of the necks to give me a good idea of the "neck tension". I do find it works best (and easiest), especially when using a mandrel to open the necks when neck wall thickness varies. If one using a bushing die, variation in neck wall thickness will show up mostly on the ID and measuring the OD is then just as good as measuring with pin gauges. If one is turning the necks to get rid of the variation in neck wall thickness, then I don't think it really matters. Though I do turn necks, I like using my pin gauges as they also help with keeping an eye on any donuts that might form, since I use non-busing FL sizing dies.

Keep in mind that there's more to this "neck tension" than the what we measure in inches. You have interference due to how smoothly the jacket of the bullet slides again the neck wall. This is where some kind of lube is often used to make the bullet slide easier in the neck (good for getting consistent seating depths). But this has a very small effect compared to the force it takes to release the bullet as the neck expands.

Using some kind of force gauge when seating bullets measures both these factors and can help get a good idea for consistency for both all in one reading.

 

[JFrank]

IMO the gages measure resistance, resistance can come from friction or a dimensional difference, the latter can be seen on paper the other one ( friction ) doesn’t really change the target but may change es/sd, I don’t concern myself with the numbers as long as they’re within reason.
Not enough bullet hold has shown up as erractic at mid to long range while a bit extra still shot well.
Whether turned necks or not turned hasn’t changed those results for me personally.

Others may have different results of course.

Jim

 

[RegionRat]

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 ?

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

 

[MikeRu]

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 ?

Get the mandrel “set” from 21st century and use them as feelers, they come in 1/2 thou increments.

 

[Allen Corneau]

I bought pin gauges in 0.0005" increments between 0.239" and 0.242" from McMaster Carr (for my 6BR).

While I don't check each and every piece of brass anymore, they have been very useful in helping me find the right combination of neck bushing and mandrel size to end up with my desired neck tension/diameter. If something doesn't feel right or I'm curious about something, I can pull out the pins and figure it out.

At $5-6 a piece it's a pretty small expense to know exactly what is going on with your brass.

 

[marchboom]

Get pin gauges in sizes above and below your desired ID neck size. Your brass will usually spring back approx. .0005" and the pin gauges will measure this accurately. Pin gauges are much cheaper than mandrels.

 

[JFrank]

The best way to measure neck tension is with a target.

Jim

 

[Chris Edmondson]

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 ?

I do measure neck tension of every piece because that function is integrated into the arbor press I use for bullet seating; it's easy to do. It measures the materialized effort required to seat a bullet, including both the tension component and the friction component of the two major forces. It can also groups rounds by seating effort, if desired. I wish I could tell you the "tight" groups shoot reliably better than the "loose" groups, they don't, for me.

What I have found is the degree of seating effort, as an average, has a sweet spot; there's too little NT, and too much NT, as indicated by the targets.

Before throwing my silly system under the bus, it's very useful for culling outliers.

I'm inclined to believe a K&M arbor with the force pack would do a great job of finding outliers and allowing the operator to fine tune the sweet spot based on the targets.

 

[Ccrider]

The best way to measure neck tension is with a target.

Jim

Yep. That is the only neck tension measurement that matters. .001 difference can show on the target.

 

[Ccrider]

.001 increases:

 

[ELR LVR]

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 ?

If you're trying to go for consistency rather than feel
(I go for feel and can pretty much tell the difference when say brass is needing to be annealed)
Try attaching some sort of pull scale to the end of your press arm
then seat a bullet
Measure the force required to insert bullet into neck
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It will at least give you some sort of idea and offer the benefit of culling outliers
it will not measure gripping force on the bullet however
-----------------------
If your press arm is long which may not register small differences
.... maybe slide the scale inward more to increase sensitivity and experiment with that

 

[CloudNein]

A lot of replies for a premier reloading forum not knowing Forster makes Neck tension gages for each main caliber.

Yes, they are essentially gauge pins , but, they are stacked together in .0005" increments.

 

[gpoldblue]

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.