Please critique my plan for setting neck tension

[precision.riflecraft]

Hi everyone, my first set of dies is on its way! I ordered a Redding Competition seating die, VLD stem and Type S FL die for the Cadex .300 PRC that's in the works. I also have a box of Lapua brass on the way. I have Retumbo, 250 gr A-Tips and CCI primers ready to roll.

I was planning to set neck tension with just the bushing in my FL die, but I saw a video that showed how the Type S dies produce up to .003 of runout with that method, whereas doing so with an expander mandrel caused less than .001 using the same brass (can't recall which brand).

So now, my plan is to bump the shoulder and size the neck down with the Type S FL, then open up the neck to its final size using a 21st Century expander mandrel die. Here's my question:

What should I set the initial tension to? My idea is to set it to .002 with the bushing, then push a .307 mandrel down to get to .001, which I've read will be about .0015 with springback. My thinking is that this will reduce working of the brass compared to a non-bushing FL die, especially with thick Lapua cases.

Is this what you guys would recommend, or should I use a tighter bushing, say, setting initial tension to .003 before opening it up with the mandrel? I'm relatively new to precision handloading.

 

[precision.riflecraft]

Oh, and to further complicate things, 21st Century's website says "The oversized expanders will also help straighten necks prior to sizing to improve concentricity."

Does this mean I should use a larger one before sizing to straighten the neck, then carry out the process described in my post with a smaller mandrel in the die? If so, what size should I order for the initial straightening?

 

[Clancy]

.002 could be insufficient if say your next batch of brass is a little smaller, which happens fairly often. I wouldn’t fret overworking the brass. I’ve put a lot of miles on Lapua 6.5x47 cases using a plain FL die and then opening with a mandrel. I do anneal every 3 firings.

I just went through all this for a 6 GT and decided to size it down .003 under a loaded round and open it with a .242 mandrel. I also have a .241 and .2415 ready should I need them. I’ll have whidden make me a FL die once I get a couple of firings on 3 pieces of brass (I hate bushing dies.)

I’ll be watching this thread myself to see what other think.

 

[Clancy]

As far as opening a fired case, this is the first time I’ve ever heard of that.

Ive let a lot of things keep me awake at night, but a little runout (a little) isn’t one of them.

 

[Ned Ludd]

There is no need to make things so complicated. Until/unless you actually generate significant runout with the new die, this is all sheer speculation. I used Redding Type S dies solely with a bushing to size necks for years with little to no runout.

If your new die actually does produce unacceptable runout, the first thing I would suggest is to remove the expander ball. I remove them from every Type S die prior to use. If that doesn't solve the issue, try starting with a bushing that is .001" smaller than you would normally use as the sole sizing step. This is to ensure the subsequent expander mandrel does work to expand the necks. Then add in a second [final] sizing step with 21st Century mandrel after the bushing die using a mandrel that is ~.0015" under bullet diameter for ~.002" neck tension (interference fit). The mandrel diameter can be adjusted up/down to yield more or less neck tension. There is no need to use an oversized mandrel (caliber or larger) first, followed by a bushing die, followed by another mandrel. Such an approach would be needlessly complicated and work the brass more than is necessary.

 

[BigWyoming]

You may be putting too much stock in concentricity.

I bump shoulder with a Wilson body die - set the neck with a Wilson neck die and then run a .3075 Wilson expander through twice. Never once spin the cartridge to see what runout is.

You got the right idea. Don't get too excited about what you have seen on video. Create you own experience and knowledge base for your equipment.

 

[precision.riflecraft]

.002 could be insufficient if say your next batch of brass is a little smaller, which happens fairly often. I wouldn’t fret overworking the brass. I’ve put a lot of miles on Lapua 6.5x47 cases using a plain FL die and then opening with a mandrel. I do anneal every 3 firings.

I just went through all this for a 6 GT and decided to size it down .003 under a loaded round and open it with a .242 mandrel. I also have a .241 and .2415 ready should I need them. I’ll have whidden make me a FL die once I get a couple of firings on 3 pieces of brass (I hate bushing dies.)

I’ll be watching this thread myself to see what other think.

Many thanks, I'll be annealing every firing with an AMP induction unit. I'm looking forward to inspecting the Lapua brass once it arrives as well. Lots to learn.

 

[precision.riflecraft]

There is no need to make things so complicated. Until/unless you actually generate significant runout with the new die, this is all sheer speculation. I used Redding Type S dies solely with a bushing to size necks for years with little to no runout.

If your new die actually does produce unacceptable runout, the first thing I would suggest is to remove the expander ball. I remove them from every Type S die prior to use. If that doesn't solve the issue, try starting with a bushing that is .001" smaller than you would normally use as the sole sizing step. This is to ensure the subsequent expander mandrel does work to expand the necks. Then add in a second [final] sizing step with 21st Century mandrel after the bushing die using a mandrel that is ~.0015" under bullet diameter for ~.002" neck tension (interference fit). The mandrel diameter can be adjusted up/down to yield more or less neck tension. There is no need to use an oversized mandrel (caliber or larger) first, followed by a bushing die, followed by another mandrel. Such an approach would be needlessly complicated and work the brass more than is necessary.

Thank you - that's a great point. I'll start with just the bushing die and see how much (if any) runout I get. In these Type S dies, I believe the expander ball is integral to the decapping pin, and since I'll be decapping in a separate step anyway, I'll be removing the pin and ball.

 

[precision.riflecraft]

You may be putting too much stock in concentricity.

I bump shoulder with a Wilson body die - set the neck with a Wilson neck die and then run a .3075 Wilson expander through twice. Never once spin the cartridge to see what runout is.

You got the right idea. Don't get too excited about what you have seen on video. Create you own experience and knowledge base for your equipment.

Cheers, at the moment I'm heavy on theory and light on experience. Looking forward to experimenting and doing more hand-on learning.

 

[Ned Ludd]

Thank you - that's a great point. I'll start with just the bushing die and see how much (if any) runout I get. In these Type S dies, I believe the expander ball is integral to the decapping pin, and since I'll be decapping in a separate step anyway, I'll be removing the pin and ball.

As I mentioned, I remove the expander ball from all my type S dies. I also remove the decapping pin assmebly, but leave the threaded shaft and nut in the die. If yours are not removable, then they must be a different design for that particular cartridge die than the ones for the cartridges I use. Regardless, if necessary, i.e. excessive runout, remove them if you possibly can and see how it works out. Running a mandrel through the necks after sizing with the bushing die will be pointless if you cannot remove the expander ball from the die first.

 

[precision.riflecraft]

As I mentioned, I remove the expander ball from all my type S dies. I also remove the decapping pin assmebly, but leave the threaded shaft and nut in the die. If yours are not removable, then they must be a different design for that particular cartridge die than the ones for the cartridges I use. Regardless, if necessary, i.e. excessive runout, remove them if you possibly can and see how it works out. Running a mandrel through the necks after sizing with the bushing die will be pointless if you cannot remove the expander ball from the die first.

Cheers Ned, I'm looking forward to having a closer look at these dies. They're with the customs gods at the Canadian border now. I ordered them from Brownell's, as no one has them in stock up here at the moment.

 

[Bill Norris]

Losing the expander from the die will be a huge help. Dont over think the process and runout. Erik Cortina shot cases with .004 runout and didnt see any differences in his groups.

 

[mikecr]

So now, my plan is to bump the shoulder and size the neck down with the Type S FL, then open up the neck to its final size using a 21st Century expander mandrel die. Here's my question:

What should I set the initial tension to? My idea is to set it to .002 with the bushing, then push a .307 mandrel down to get to .001, which I've read will be about .0015 with springback.

It's a good plan all the way. I don't think you'll have a problem.
When you size down necks without re-expansion (or pre-seating expansion), thickness variance is driven inward, and bullets will not seat straight against it.
What mandrels do to reduce runout is push thickness variances outward -away from seating bullet bearing.

About mandrels straightening necks? That's just merchandising..
A neck would have to be incredibly skewed, and not offset with that, for a mandrel to help any with that.
Best to just fire form that out(after a good annealing).

 

[precision.riflecraft]

Losing the expander from the die will be a huge help. Dont over think the process and runout. Erik Cortina shot cases with .004 runout and didnt see any differences in his groups.

Interesting! I must've missed that video. I will definitely remove the expander ball.

 

[precision.riflecraft]

It's a good plan all the way. I don't think you'll have a problem.
When you size down necks without re-expansion (or pre-seating expansion), thickness variance is driven inward, and bullets will not seat straight against it.
What mandrels do to reduce runout is push thickness variances outward -away from seating bullet bearing.

About mandrels straightening necks? That's just merchandising..
A neck would have to be incredibly skewed, and not offset with that, for a mandrel to help any with that.
Best to just fire form that out(after a good annealing).

Many thanks, that was exactly my reasoning, and I'll be annealing every time with an AMP induction unit.

 

[Coyotefurharvester]

Don't forget the o ring under the lock ring trick to reduce runouut.

 

[JFrank]

Hi everyone, my first set of dies is on its way! I ordered a Redding Competition seating die, VLD stem and Type S FL die for the Cadex .300 PRC that's in the works. I also have a box of Lapua brass on the way. I have Retumbo, 250 gr A-Tips and CCI primers ready to roll.

I was planning to set neck tension with just the bushing in my FL die, but I saw a video that showed how the Type S dies produce up to .003 of runout with that method, whereas doing so with an expander mandrel caused less than .001 using the same brass (can't recall which brand).

So now, my plan is to bump the shoulder and size the neck down with the Type S FL, then open up the neck to its final size using a 21st Century expander mandrel die. Here's my question:

What should I set the initial tension to? My idea is to set it to .002 with the bushing, then push a .307 mandrel down to get to .001, which I've read will be about .0015 with springback. My thinking is that this will reduce working of the brass compared to a non-bushing FL die, especially with thick Lapua cases.

Is this what you guys would recommend, or should I use a tighter bushing, say, setting initial tension to .003 before opening it up with the mandrel? I'm relatively new to precision handloading.

How did you arrive at .001 bullet hold being optimum ?

 

[mgunderson]

Your set up and dies may not behave like the internet says. Measure and adapt. Find an experienced competitor so you have someone local to ask.

Many of the YouTube people are very accomplished shooters. It way take some time to benefit from all their wisdom. It takes longer to make great ammo and at times I should have settled for shooting more ammo that was "good enough".

 

[precision.riflecraft]

Don't forget the o ring under the lock ring trick to reduce runouut.

I'm not familiar with that technique. Can you elaborate? I have a Forster Co-Ax, which free-floats the die to reduce runout.

 

[precision.riflecraft]

How did you arrive at .001 bullet hold being optimum ?

Certainly not experience - just internet research, mostly from reputable YouTube channels like Erik Cortina's. What are your thoughts on neck tension?