Neck Tension - Serria Article

[K22]

Excellent article in the Daily Bulletin on neck tension written by Sierra.

I actually obtained a similar article many years ago when Sierra had a reloading Newsletter that I would occasionally receive.

For simple minded people like me () I've using the expander ball method for many years now with excellent results on target. I have a range of sizes, sized and polished as the article describes which I can use to give me optimum neck tension for a specific rifle, brand / lot of cases.

It can be an economical alternative to those who want to use their standard FL die and improved tension control but don't want to invest in bushing dies and bushings and / or get involved with neck turning. I am not suggesting that is better or even as precise and effective as bushings, but it does work at least for me for varmint grade accuracy.

I also use a rubber "O" ring under the assembly which allows the expander assembly to "float" to aid it helping keep the neck aligned with the body of the case.

 

[RegionRat]

https://bulletin.accurateshooter.co...ck-tension-with-bushings-expanders-annealing/

I hot linked it since the Daily Bulletin keeps adding more articles.

 

[Rocketvapor]

For those that use regular, cheap FL dies, measure what your die is doing to your brass BEFORE it expands it back out. Most really scrunch the neck down before the the ball, mandrel or whatever expands it back out.
That's a lot of work being done to the neck.
While I normally use a body only die followed by a Lee Collet Die, I sometimes use an easy to modify FL die
(or a small base FL die).
For .224 size bullets, and a 0.012 to 0.013" neck thickness, I run a Carbide 6 flute reamer through the neck area. 0.2475" is easy to find on E-bay. Now the FL die works the brass a lot less and the expander is a lot easier to pull out, probably distorting the case less.
A 0.250" reamer on a FL die glazes over the neck area and still requires the LCD to get any tension.

The Body only die (for various .224 calibers) has a neck opening about 0.260" and doesn't touch the neck except when I bump down 6mm Hagar cases to 22 Nosgar. Then the LCD with an undersized mandrel.
Measure and pick the reamer you need.

Here's what the body die and LCD does when I bump down the 6mm Hagar brass;

I anneal after abusing the neck like that.

The reamed Dies pass a 0.247"+ pin, while the stock dies pass a 0.243"+ pin.
I ID the modified dies with a little cold blue.

 

[okie]

measure what your die is doing to your brass BEFORE it expands it back out. Most really scrunch the neck down

truth

 

[rebs]

I use a Redding fl bushing die with the expander button. Sometimes I feel it pulling out of the brass and sometimes it don't pull at all. Why is that ?

 

[rijndael]

I use a Redding fl bushing die with the expander button. Sometimes I feel it pulling out of the brass and sometimes it don't pull at all. Why is that ?

It sounds like you have neck thickness variation. The bushing works on the OD, so it's giving you varying neck IDs if the thickness is inconsistent.

 

[Tesoro]

I exclusively use Lapua brass and now sizing with bushings ( again). For those who dont turn necks and shoot out of ultra match chambers, like me, I have always wondered if having more bullet grip like 5 thou would be more consistent than trying to keep an even light grip of 2 thou. I loaded some 6br at 5 tho so will see what happens!

 

[rijndael]

I have always wondered if having more bullet grip like 5 thou would be more consistent than trying to keep an even light grip of 2 thou.

IME, yes. I use .004 under.

With .002 under, you can feel the mandrel go in with a lot of pressure variation.

 

[BoydAllen]

I exclusively use Lapua brass and now sizing with bushings ( again). For those who dont turn necks and shoot out of ultra match chambers, like me, I have always wondered if having more bullet grip like 5 thou would be more consistent than trying to keep an even light grip of 2 thou. I loaded some 6br at 5 tho so will see what happens!

In my experience, it depends on the powder. Different powders "like" different amounts of neck tension. Fortunately, with a selection of neck bushings, you can test the powder you are using to determine what works best.

 

[Tesoro]

In my experience, it depends on the powder. Different powders "like" different amounts of neck tension. Fortunately, with a selection of neck bushings, you can test the powder you are using to determine what works best.

Those were the days!’ (Powders)

 

[Tesoro]

IME, yes. I use .004 under.

With .002 under, you can feel the mandrel go in with a lot of pressure variation.

You final size with a mandrel and keep to a tho max wobble? Which die?

 

[SecondsCount]

It sounds like you have neck thickness variation. The bushing works on the OD, so it's giving you varying neck IDs if the thickness is inconsistent.

It could also be a variance in brass hardness.

 

[Idaho-Lefty]

truth

See first Para of Post #3,..
Custom "Honing" neck Dia's on Forster Dies is,.. "MONEY" !!!
Just be sure of, the amount of Neck "Tension"... you desire.
Most regular Dies seriously,.. OVERWORK,. the Brass !

 

[rijndael]

It could also be a variance in brass hardness.

Yes, could be. I anneal every time, so I worry less about hardness.

 

[rebs]

It sounds like you have neck thickness variation. The bushing works on the OD, so it's giving you varying neck IDs if the thickness is inconsistent.

this is with Lapua once fired 77 OTM brass

 

[rijndael]

You final size with a mandrel and keep to a tho max wobble? Which die?

I use a .004" under, finish with a .002" or .0025" under mandrel.

I'd say total wobble is under .002", I can't say all are under .001"

I plan to test the new Cortina expander die, which may reduce it a bit, but I don't know that runout makes a difference for what I do. I do pay attention to it, because it helps me track things, but I don't know that it matters on paper/steel.

ETA: The die is either an RCBS MatchMaster or Whidden. It depends on the caliber.

 

[Tesoro]

I use a .004" under, finish with a .002" or .0025" under mandrel.

I'd say total wobble is under .002", I can't say all are under .001"

I plan to test the new Cortina expander die, which may reduce it a bit, but I don't know that runout makes a difference for what I do. I do pay attention to it, because it helps me track things, but I don't know that it matters on paper/steel.

ETA: The die is either an RCBS MatchMaster or Whidden. It depends on the caliber.

Ok. I have a 21c mandrelI I use on new cases and dents. I have experimented using it as a finisher instead of bushing but runout goes from nothing to all over the place. I dont subscribe to the ‘push irregularities to the outside’ unless maybe one was doing some major undersizing-expanding. I dont know how straight ammo really needs to be but I like it straight. Makes me shoot better psychologically!!

 

[rijndael]

I dont subscribe to the ‘push irregularities to the outside’ unless maybe one was doing some major undersizing-expanding.

I'm kind of there as well. I arrived at using the mandrel, rather than just the neck bushing, because of force variations I noticed when seating bullets. Then I wanted to clean up my chrono numbers so I was playing around neck tension differences - more than just with bushing diameters - and I just kept using it.

 

[Tesoro]

I was looking at Erik Cortina's shopping page and he makes a neck madrel die that is also a body die...ie aligned. This would work for those who want to go that route.