Neck Tension

[parshal]

I played around with neck tension quite a bit this summer in my 65 SS. I used .002" for load development. Once I had a good load I settled on using a .291 bushing followed by a .2635 mandrel. I anneal every firing. Logic would suggest that .0005" tension isn't nearly enough. But, the bullets are held tightly and I get great ED/SD. I can't push the bullet in without a lot of force.

 

[skipglo]

Typically neck tension runs between 0.001-0.003. Most guys stay around 0.002-0.003 for best results with hunting and field rifles. You check it by sizing a piece of brass, measure the outside diameter of the neck after sized. Then seat a bullet in that sized case and measure the outside diameter of your case. If your sized case was 0.310 for example and it's 0.312 after seating a bullet, then you have 0.002 of neck tension. All of the standard dies I use size the brass to have 0.0015-0.002 neck tension. The only way to adjust neck tension is to buy bushing sizing dies. With those, seat a bullet, measure the neck O.D., subtract how much neck tension you want and order that bushing. So again, 0.312 loaded neck diameter and you want 0.003 of neck tension, then order a 0.309 bushing.

Well done Jud! ( Even if you do like used, un-broken actions...lol)

 

[Double Dropper]

Valuable input

 

[257RobertsMan]

Typically neck tension runs between 0.001-0.003. Most guys stay around 0.002-0.003 for best results with hunting and field rifles. You check it by sizing a piece of brass, measure the outside diameter of the neck after sized. Then seat a bullet in that sized case and measure the outside diameter of your case. If your sized case was 0.310 for example and it's 0.312 after seating a bullet, then you have 0.002 of neck tension. All of the standard dies I use size the brass to have 0.0015-0.002 neck tension. The only way to adjust neck tension is to buy bushing sizing dies. With those, seat a bullet, measure the neck O.D., subtract how much neck tension you want and order that bushing. So again, 0.312 loaded neck diameter and you want 0.003 of neck tension, then order a 0.309 bushing.

jud96,
I'm new to the forum and trying to learn from all of you that know way more than I do. I've been reloading on and off for about 40 years and never used bushing sizing dies but am very interested & trying to learn. My question is, when ordering your bushing do you measure neck OD, then load and measure again (to take into account the already existing tension) and then subtract to arrive at your desired tention or am I looking at this all wrong?

 

[Jud96]

jud96,
I'm new to the forum and trying to learn from all of you that know way more than I do. I've been reloading on and off for about 40 years and never used bushing sizing dies but am very interested & trying to learn. My question is, when ordering your bushing do you measure neck OD, then load and measure again (to take into account the already existing tension) and then subtract to arrive at your desired tention or am I looking at this all wrong?

It doesn't matter what your neck tension previously was. All that matters is your loaded round neck outside diameter. Your bullet diameter and neck thickness will always remain the same, whether you have 0.001 neck tension or 0.005 neck tension.

 

[vancewalker007]

jud96,
I'm new to the forum and trying to learn from all of you that know way more than I do. I've been reloading on and off for about 40 years and never used bushing sizing dies but am very interested & trying to learn. My question is, when ordering your bushing do you measure neck OD, then load and measure again (to take into account the already existing tension) and then subtract to arrive at your desired tention or am I looking at this all wrong?

Like Jud96 said. You measure your final brass outside diameter after your last neck sizing step, then seat a bullet and do the same measure again. For example my 6.5 PRC final sizing puts my cases at .290-.2905, I seat a bullet and remeasure to find it at .292-.2925. This is essentially the basic method to check what your tension is once you have a a bushing.

You can get a rough idea of where to start by looking at the spec on your cartridge then picking a couple of bushings that will get you close to where you want to experiment. You'll never guess right the first time. Your rifle might like 3 thou or 2 thou of tension. You have to build them and shoot. Usually most people find their best groups in the 1-3 thou range.

You should not drop the neck size more than 5 thou in a step. You will always need an intermediate bushing unless you have a really tight match chamber. So on my current 6.5 setup I use a .293 to drop from a shot .297-.298 then a final .290 to get my .002 tension. I tried a .289 with several loads and it shot worse then the .290, so it's .290 for now.

It takes a little experimenting to get it right for your rifle, and you need to use the same brass manufacturer because brass varies a lot.

 

[257RobertsMan]

It doesn't matter what your neck tension previously was. All that matters is your loaded round neck outside diameter. Your bullet diameter and neck thickness will always remain the same, whether you have 0.001 neck tension or 0.005 neck tension.

Thanks Jud96 & Vancewalker 007!

But I'm old, slow & still confused! Lol
If I resize and get an OD of .290, seat bullet and get an OD of .292 (.002 tension) but want .003 tension, what bushing do you order.

 

[vancewalker007]

Thanks Jud96 & Vancewalker 007!

But I'm old, slow & still confused! Lol
If I resize and get an OD of .290, seat bullet and get an OD of .292 (.002 tension) but want .003 tension, what bushing do you order.

If you want another thou just go down 1 thou on your final bushing. So in your example you would use a .289. Some brass my exhibit some spring back so sometimes a given bushing will not fully size it down. I've noticed this with thicker brass.

 

[257RobertsMan]

Thanks Guys, after re-reading your posts several times and doing the math I think I finally got it figured out. Once loaded 6 rounds for a DPMS .223 from Wal-Mart and shot a 100 yd, 6 shot group of .0425" so even an old slow guy gets it right sooner or later.

 

[beaver hunter]

I've been following this thread, as I am also trying to figure out and properly neck size a couple of rifles, a couple of posts back someone said it didn't effect the. ES / SD. , what does es/ sd mean ?

 

[Deleted member 107796]

It doesn't matter what your neck tension previously was. All that matters is your loaded round neck outside diameter. Your bullet diameter and neck thickness will always remain the same, whether you have 0.001 neck tension or 0.005 neck tension.

I agree with your point but it is physically impossible for the neck thickness to be the same for different amounts of stretching, albeit is very tiny amount.

 

[MoaFlat]

Neck tension is critical for reloading. My recipe is full length size only without expander ball. I use a K&M expander as a separate step in brass prep, on occasion I will modify the expander OD to match neck tension sought or stay with the full length size same as projectile. Key control areas are:
- neck wall thickness important / options neck turn or ream ID
- neck annealed or soft enough to retain consistent OD sought
- measure or gauge by hand amount of tension to seat - if not smooth as butter Stop Immediately and fix so that it is.
- inner neck surface important- 100% burnish if necessary
- Check neck tension acid test by dismantling projectile if it requires considerably more force to break free (resolve why) - it should be smooth and easy with .0015 to .002" neck tension
- sometimes a neck dry lube is necessary to have uniform tension: dry mica, graphite...few others
- many projectiles have lot to lot OD inconsistency- take care
- annealing for neck tension consistency important to check.. brass hardness will spring back to size unknown where soft annealed necks will not and stay in tolerance zone sought

Hope that helps

 

[bigedp51]

Bushing dies work best with with custom tight neck chambers and neck turned brass. If you have a off the shelf factory rifle with a SAAMI chamber and neck turn your brass the neck will have to expand even more. Meaning you end up working the neck even more reducing its diameter. And reducing the neck diameter .004 or more with a bushing die can induce neck runout.

Below is a cutaway of a bushing die, the area marked in red is the section of the neck that is not sized. You can also see the clearance along the sides of the bushing. The bushing floats inside the die and the bushing can move from side to side and even tilt when sizing the neck and induce neck runout. So again a bushing die works best in tight neck chambers where the bushing does not have to reduce the neck diameter excessively.

Below Redding tells you if do not neck turn and the necks vary .002 or more to use the expander that comes with the Redding die.

Tech Line & Tips (FAQs)
Bushing Selection
"The methods of determining bushing size require that the cases being sized have a fairly uniform neck wall thickness or have been neck turned. If the neck wall thickness varies more than 0.002", it may be necessary to use a bushing a couple of thousandths smaller than your calculations indicate, and then use a size button in the die to determine the final inside neck diameter."

Bottom line, with a off the shelf factory rifle you may be better off with a Forster non-bushing die with a honed neck and reduced neck runout. And at the Whidden custom die website they tell you they get more concentric cases with non-bushing full length dies.

So if you do not have a neck thickness gauge and a runout gauge using a bushing die may not be to your advantage. Too much of what benchrest shooters do with their custom rifles does not apply to the average reloader with off the shelf factory rifles.

 

[Mrhounddog]

I've been following this thread, as I am also trying to figure out and properly neck size a couple of rifles, a couple of posts back someone said it didn't effect the. ES / SD. , what does es/ sd mean ?

ES- Extreme Spread
SD- Standard Deviation

Look those up for a thorough explanation and a good understanding.

Fellas,
I have been reloading for 40 years, and I am seeing acronyms and abbreviations that I do not recognize. Take a minute to spell out these things sometimes.
And for gosh sakes, use their, there, and they're in the right places.