Neck Tension Question - Redding Type S Bushings

[LawnMM]

I have Redding type S full length and neck sizing dies. I full length resize with a bushing about halfway between fully blown open from firing to proper tension. After cleaning the lube off I neck size it down a smidge farther to the proper tension.

I had been setting neck tension to 0.332"...well, during the course of working up a new load I wound up with some rounds loaded hotter than I wanted. I used a collet RCBS puller to pull the cases off the bullets. When I went to reload them, I noticed the necks, measured with the calipers, were 0.331". This made sense as I could feel it was a smidge easier to seat the rounds. Somewhere during the bullet pulling the necks got stretched about 0.001" and made for easier seating.

I decided to fire them that way to see if the slightly lighter neck tension produced any tighter groupings with the new load. Here's what I came up with...

Its a tight grouping. 4 shots into 0.370". I don't believe in discounting 'fliers' because a flier is really the shooter jerking the trigger. That said I have a decent excuse, something like an 8mm Mauser going off when I was 95% through my pull all of two feet to my left. I flinched.

Here's the question, I had been using a 0.330" bushing to set neck tension with the neck die. With the round loaded it produced a 0.332" outer diameter neck. Do I want a 0.299" bushing to load out to 0.331" or is that going to be tighter? Would I want a 0.331" bushing to swell out to 0.333"?

I think I want a 0.299" bushing as the swell out diameter will be smaller, less tension I would think, or do I have it backwards?

Rich

 

[turbo54]

Re: Neck Tension Question - Redding Type S Bushings

I don't think you've provided enough info to get a proper answer.

Do you have any case neck wall thickness measurements?

Is your .332" bushing ACTUALLY leaving you with a .322" case neck OD (before bullet seating)?

Essentially, neck "tension" is:

Caseneck OD (bullet seated) - Caseneck OD (after sizing, before seating)

That said, based on my own experimentation, you really can't have more than .003" neck "tension", because brass isn't that springy.

Example: If you size a 308 neck to say, .295", then seat a bullet, then remove the bullet, your neck will now be .3050"-.3065".

Anyway, if you feel your accuracy has increaed by decreasing your neck tension by .001", then you need to get a new bushing that is .001" LARGER than your current one.

Hope this helps.

 

[FLIGHT762]

Re: Neck Tension Question - Redding Type S Bushings

If you want less neck tension, you would go to the .331" bushing. Going to a .329" will give you tighter tension.

For Winchester brass, I use a .331" bushing, for Hornady brass, .333" and for Federal brass, I use a .337". I picked my bushings by measuring the outside diameter of loaded rounds, minus .001". This is what was recommended by Redding. Some will recommend the measurement minus .002" for bolt guns and minus .003" for a gas gun. The minus .001" measurement has worked well for me.

I bought a spare bushing in .335" in case I wanted to go tighter with Federal brass.

If I give a light (50-60%) neck turning on the Hornady brass, I will use the .331" bushing.

You didn't post what brass you are using and how you made your bushing measurements.

 

[mdmp5]

Re: Neck Tension Question - Redding Type S Bushings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LawnMM</div><div class="ubbcode-body"> I think I want a 0.299" bushing as the swell out diameter will be smaller, less tension I would think, or do I have it backwards?

Rich </div></div>

You mean a 329 bushing

 

[LawnMM]

Re: Neck Tension Question - Redding Type S Bushings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">I don't think you've provided enough info to get a proper answer.

Do you have any case neck wall thickness measurements?

Is your .332" bushing ACTUALLY leaving you with a .322" case neck OD (before bullet seating)?

Essentially, neck "tension" is:

Caseneck OD (bullet seated) - Caseneck OD (after sizing, before seating)

That said, based on my own experimentation, you really can't have more than .003" neck "tension", because brass isn't that springy.

Example: If you size a 308 neck to say, .295", then seat a bullet, then remove the bullet, your neck will now be .3050"-.3065".

Anyway, if you feel your accuracy has increaed by decreasing your neck tension by .001", then you need to get a new bushing that is .001" LARGER than your current one.

Hope this helps. </div></div>

The OD of the brass is 0.330 after sizing, 0.332 with bullet seated. If I get a larger bushing, that should make it 0.331 before seating, 0.333 after seating. The OD on these cases were measuring 0.331, which is sort of counter intuitive because its a smaller diameter with the bullet seated, but the tension was lighter than before, if that makes sense. The feel was easier, though the OD of the seated bullet was 0.331 instead of 0.332.

I'm not really sure if I need to lighten the tension up or not. The feel when seating was that the tension was lighter. The measurements on the OD of the case suggest it was tighter. I have conflicting info. Feel says looser, measurements say lighter.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FLIGHT762</div><div class="ubbcode-body">If you want less neck tension, you would go to the .331" bushing. Going to a .329" will give you tighter tension.

For Winchester brass, I use a .331" bushing, for Hornady brass, .333" and for Federal brass, I use a .337". I picked my bushings by measuring the outside diameter of loaded rounds, minus .001". This is what was recommended by Redding. Some will recommend the measurement minus .002" for bolt guns and minus .003" for a gas gun. The minus .001" measurement has worked well for me.

I bought a spare bushing in .335" in case I wanted to go tighter with Federal brass.

If I give a light (50-60%) neck turning on the Hornady brass, I will use the .331" bushing.

You didn't post what brass you are using and how you made your bushing measurements. </div></div>

Its Winchester brass. I mic'd the OD of the case after seating the bullets.

When I originally bought the bushings, I read to subtract 0.002" from the OD of a loaded round for the proper bushing tension. OD was 0.332" loaded, so I bought a 0.330" bushing for final neck tension.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: palmik</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LawnMM</div><div class="ubbcode-body"> I think I want a 0.299" bushing as the swell out diameter will be smaller, less tension I would think, or do I have it backwards?

Rich </div></div>

You mean a 329 bushing </div></div>

I do, thanks for catching that.


What I'm struggling with is the conflicting measurements versus feel when seating. When I went to seat the bullets, having pulled the bullets to adjust the charge made them seat easier. Hence my belief that a slightly looser neck tension made for better accuracy. The OD of the loaded rounds was actually tighter than before, todays measured 0.331" when historically they have measured 0.332"

I think I'm going to try a 0.331" bushing, its 0.001" less neck tension, and its what Flight is using on his Winchester brass so I will give that a whirl and see what happens.

Rich

 

[turbo54]

Re: Neck Tension Question - Redding Type S Bushings

You've got bigger problems..

Regardless of neck size after sizing, your diameter with bullet seated WILL remain the same....

Bushing size has no impact on loaded neck diameter (except after time due to increased/decreased brass flow to the neck).

 

[turbo54]

Re: Neck Tension Question - Redding Type S Bushings

If you are currently at .330 after sizing, and .332 after seating, then increasing bushing size by .001" will yield .331 after sizing and AGAIN, .332 after seating! Thus, decreasing neck tension by .001".

Look again at the formula I posted in my first post for calculating neck tension.

 

[LawnMM]

Re: Neck Tension Question - Redding Type S Bushings

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">If you are currently at .330 after sizing, and .332 after seating, then increasing bushing size by .001" will yield .331 after sizing and AGAIN, .332 after seating! Thus, decreasing neck tension by .001".

Look again at the formula I posted in my first post for calculating neck tension. </div></div>

That makes sense, finally. Thanks.

 

[turbo54]

Re: Neck Tension Question - Redding Type S Bushings

No sweat! Glad I could help shed light.

 

[Blackhawk 1]

Re: Neck Tension Question - Redding Type S Bushings

Great thread I just started using Redding bushing dies and set up using info here.

 

[remaction]

Re: Neck Tension Question - Redding Type S Bushings

In regards to your statement:
"What I'm struggling with is the conflicting measurements versus feel when seating. When I went to seat the bullets, having pulled the bullets to adjust the charge made them seat easier. Hence my belief that a slightly looser neck tension made for better accuracy. The OD of the loaded rounds was actually tighter than before, todays measured 0.331" when historically they have measured 0.332"

Unless you have turned your necks, the O.D. difference was probably due to typical neck wall variances in the brass. Measure some to confirm. At any rate, Turbo54 has given you the answer you needed.