Quantification of neck tension.

[jmorris]

I have to admit to doing a lot by feel over the years and learned what feels shot well and what one’s didn’t. The most recent annealing thread peaked my interest.

So, I grabbed a 7/8-14 bolt and drilled out the center, faced the head flat, welded a nut to the top that the ram could thread into, and machined an adapter to the end I could secure the mandrel out of my Sinclair expander die.



This threads into the top of the press and measures the force it takes to push the expander into the case.


Used Imperial on the cases and expander mandrel consistently with all of them.

I took 4 once fired LC cases and sized them with RCBS p/n 11103 dies (complete with decapping pin/expander) and then expanded them once again with the Sinclair. A low of ~92 with a high of 99. Now that’s in PSI and the surface area of the cylinder I used is only .4418 in^2 so the force was actually 40-43.7 lbs. 2nd stroke with the expander took it to 35.3 lbs and they lost about 2.2 lbs per stroke down to 26.5 lbs and stayed there even after many (10+) strokes. The other 3 were similar in variation of about 10 lbs max to min.

After running them all back through the RCBS die again, I annealed two, using propane just until the first evidence of the flame changing from blue to orange. Then again with the Sinclair, 39.7 lb first stroke, 46.3 lb #2 and they stayed there for another 10 strokes.

The other two I heated to a “glow”, went 8.8 lbs on first stroke 4.2 on second and zero on #3. Again both acted similar. Next, I ran one in and out of the RCBS die 12 times and back to the Sinclair expander and it did in fact improve with 26.5 lb on the first stroke, 17.6 on the 2nd and back to ~9 lbs after that.

Not really an in-depth study and obviously not working the brass like firing would but might give some food for thought.

 

[AJC1]

I have to admit to doing a lot by feel over the years and learned what feels shot well and what one’s didn’t. The most recent annealing thread peaked my interest.

So, I grabbed a 7/8-14 bolt and drilled out the center, faced the head flat, welded a nut to the top that the ram could thread into, and machined an adapter to the end I could secure the mandrel out of my Sinclair expander die.

View attachment 1144532 View attachment 1144534

This threads into the top of the press and measures the force it takes to push the expander into the case.

View attachment 1144533
Used Imperial on the cases and expander mandrel consistently with all of them.

I took 4 once fired LC cases and sized them with RCBS p/n 11103 dies (complete with decapping pin/expander) and then expanded them once again with the Sinclair. A low of ~92 with a high of 99. Now that’s in PSI and the surface area of the cylinder I used is only .4418 in^2 so the force was actually 40-43.7 lbs. 2nd stroke with the expander took it to 35.3 lbs and they lost about 2.2 lbs per stroke down to 26.5 lbs and stayed there even after many strokes. The other 3 were similar an variation of about 10 lbs max to min.

After running them all back through the RCBS die again, I annealed two, using propane just until the first evidence of the flame changing from blue to orange. Then again with the Sinclair, 39.7 lb first stroke, 46.3 lb #2 and they stayed there for another 10 strokes.

The “glowing” cases, went 8.8 lbs on first stroke 4.2 on second and zero on #3. Again both acted similar. Next, I ran one in and out of the RCBS die 12 times and back to the Sinclair expander and it did in fact improve with 26.5 lb on the first stroke, 17.6 on the 2nd and back to ~9 lbs after that.

Not really an in-depth study and obviously not working the brass like firing would but might give some food for thought.

I completely follow your mindset. I enjoy your contributions.

 

[CoalCrackerAl]

Very interesting.

 

[FROGO207]

Yes interesting! Also thank you for taking your time to explain the experiment and documentation of your results.
Much better than just saying "it feels different" when sizing and after annealing.

 

[jmorris]

Yes interesting! Also thank you for taking your time to explain the experiment and documentation of your results.
Much better than just saying "it feels different" when sizing and after annealing.

Yes, I was very excited when I was the one that got all of my Grandmothers recipes, upon Her passing. Then had to figure out how to quantify her amounts…

It’s pretty hard to explain senses, kind of like, you could learn more in 30 minutes with a good welder than you could reading 300 pages they wrote. I would have made a video but it would have been a couple hours too long…

 

[JFrank]

Maybe I’m misunderstanding the test but it sounds like you used a mandrel multiple times on the same case, noting the changes with each stroke before and after annealing. Is that correct ?

 

[Walkalong]

Neat setup. I use the old feels just right method of consistent seating pressure/neck tension.

 

[Walkalong]

https://21stcenturyinnovation.com/buy-online/ols/products/hydro-bullet-seater

 

[PWC]

Well, this answers a way to measure neck tension...its in lbs and not "tensions", should warm the cockles of fguffey's heart that someone besides him found a way to measure "neck hold."

 

[JFrank]

There are a few ways to measure bullet hold and there’s also a difference between seating force from friction and seating force from a dimensional difference.
Dimensional difference lessens each time the lever is operated putting a mandrel into a case. Since we only seat bullets one time per session (typically)I don’t know what we’ve learned here without comparing seating force of multiple cases in different stages of annealing.

 

[N555]

I get a few that don't feel right when seating the bullet. They go in the range fodder pile to be used as fouling shots, blasting a wet or goopy, messy targets at really close range, ect.
I still end up loading random head stamps to satisfy my range fodder needs.

 

[kmw1954]

Follow with intense interest.

 

[LiveLife]

7/8-14 bolt and drilled out the center, faced the head flat, welded a nut to the top that the ram could thread into, and machined an adapter to the end I could secure the mandrel out of my Sinclair expander die.

This threads into the top of the press and measures the force it takes to push the expander into the case

I like measurable repeatable data.

I use the old feels just right method of consistent seating pressure/neck tension.

It was jmorris along with Bart B. and other THR members that challenged my methods of testing and data collection that prompted me to "quantify" neck tension by measuring bullet setback - https://www.thehighroad.org/index.p...neck-tension-and-bullet-setback.830072/page-4

While jmorris' setup to "quantify" neck tension is admirable, I wonder how the measurements will translate to bullet setback after bullet nose impacts/bumps the feed ramp. Perhaps a threshold number can be extracted where bullet setback for specific feed ramp/angle and force of recoil spring rate won't produce bullet setback.

Following thread with interest.

 

[lordpaxman]

I wonder if you tracked this force through the sizing, expanding and seating if it could be attributed to precision?
Following with interest as well!

 

[jmorris]

Maybe I’m misunderstanding the test but it sounds like you used a mandrel multiple times on the same case, noting the changes with each stroke before and after annealing. Is that correct ?

I knew that was a frustrating way to present the data but I was kind of done for the day.

1x fired and sized, then the expander pushed through a number of times.

Stroke 1 = 43.7lb
2 = 35.3lb
3,4,5,6,7 losing ~2.2 lbs per stroke down to 26.5 lbs and stayed there with repeated strokes not going higher or lower.

Using the first method of annealing.
Stroke 1= 39.7 lb
Stroke 2 = 46.3 lb and didn’t change after that, even with more than 10 subsequent strokes.

Using the 2nd method of annealing.
Stroke 1= 8.8lb
2= 4.2lb
3=0

Resized that case 12 times.
Stroke 1= 26.5lb
2= 17.6
3=8.8 and didn’t change with subsequent strokes.

https://21stcenturyinnovation.com/buy-online/ols/products/hydro-bullet-seater

If I were going to spend any money in the endeavor, I’d probably add a couple hundred more and get this one.

https://www.shootingsoftware.com/recoil.htm

I don’t know what we’ve learned here without comparing seating force of multiple cases in different stages of annealing.

Not much, except over annealing substantially reduces neck tension. Even that is with a tiny sample size using only 1 brand of brass. There is a pretty big rabbit hole, testing cases, methods, lubes and such, I’m trying not to fall into.

 

[JFrank]

If you seat a bullet in a case, it will have resistance. Pull the bullet and re seat that same bullet without re sizing and you’ll have less resistance whether you are annealed or not. A mandrel is the same as a bullet.

 

[CQB45ACP]

Impressive per usual. This is so far beyond my abilities to understand is why I hand polish brass.

 

[jmorris]

If you seat a bullet in a case, it will have resistance. Pull the bullet and re seat that same bullet without re sizing and you’ll have less resistance whether you are annealed or not. A mandrel is the same as a bullet.

That makes sense but isn’t what happened. At the time I knew I should have just gathered everything up in one spot and video the exercise.

They all “settled” at some point to a repeatable amount of force despite the number of strokes. The only one that went to zero was the glowing annealed case and it did come back 60% with repeated sizing (x12).

I suppose the shocker for me was the one that was “lightly” annealed actually went up in force required after the first stroke and stayed there, even with repeated strokes. That, I probably will repeat (if it’s not an anomaly) as it is counter intuitive.

 

[N555]

That makes sense but isn’t what happened. At the time I knew I should have just gathered everything up in one spot and video the exercise.

They all “settled” at some point to a repeatable amount of force despite the number of strokes. The only one that went to zero was the glowing annealed case and it did come back 60% with repeated sizing (x12).

I suppose the shocker for me was the one that was “lightly” annealed actually went up in force required after the first stroke and stayed there, even with repeated strokes. That, I probably will repeat (if it’s not an anomaly) as it is counter intuitive.

Yeah discovered this about 25 years ago. Annealing by definition stress relieves the brass. If you measure the brass before and after the heat you will find the dimensions change, the brass likes to shrink especially on a shape like a tube. That's why I anneal to near dead soft then size with standard FL sizer with ball expander, working some hardness back into the brass and it's always dimensionally perfect. The neck is always -0.002 of the bullet size and the head spacing variably isn't usually detectable on a dial caliper. I figured that's petty good for ruined brass. If sizing it once doesn't work enough hardness back into the brass, like with dead soft 30-30, hit the sizer die 2x.
I don't waste time trying to anneal sized brass. Getting it too hot making it too soft, changing the dimensions on the brass, or it doesn't get hot enough and nothing happens.

 

[PWC]

I understand what you did, and the results. But, wouldn't it be a better measure if you took 5 cases, processed them the same, then measured each with one stroke; after all the bullet gets seated, usually, with one stroke?

After seating, measure CBTO then run thru the firearm action, assuming semi-auto, bolt, lever, or pump, and measure again for setback.

What is the best neck tension / bullet hold for your need? Only the target can tell.

 

[AJC1]

There are a few ways to measure bullet hold and there’s also a difference between seating force from friction and seating force from a dimensional difference.
Dimensional difference lessens each time the lever is operated putting a mandrel into a case. Since we only seat bullets one time per session (typically)I don’t know what we’ve learned here without comparing seating force of multiple cases in different stages of annealing.

We learned we need to neck size rounds that we are recovering for components.... for tensions sake.
We also learned that the plastic deformation was not complete based on the dwell time of the mandrel.

 

[jmorris]

I understand what you did, and the results. But, wouldn't it be a better measure if you took 5 cases, processed them the same, then measured each with one stroke; after all the bullet gets seated, usually, with one stroke?

After seating, measure CBTO then run thru the firearm action, assuming semi-auto, bolt, lever, or pump, and measure again for setback.

What is the best neck tension / bullet hold for your need? Only the target can tell.

A larger sample size is always is better for understanding things and I agree 100% on the target part. I have already done all of that though, just didn’t have any way to quantify what way worked better than others, on target.

I think the device I linked to in #15 would be neat to play with as well but like you said, the target is the important part. When we feel the one that’s “not right” we could see by how much it’s not.

Then sort them by seat force, and shoot some groups and see if it matters to you.



If I had the ammunition sorted by seat force above, first thing I would do is shoot a 12 shot group with the 72lb ammunition then another with one round each from 67-78lb. That’s still a small sample size but I enjoy not only figuring out what works best but why too and it’s always good to know what things don’t really matter much.

 

[kmw1954]

Gee thanks guys, I'm still sorting out OCW and ladder nodes by speed or accuracy. Not to mention which brand bullet at which weight shoots best in this gun. Jamb or Jump. So much to do, so much barrel life.

 

[Walkalong]

So little barrel life.

 

[kmw1954]

So little barrel life.

You caught it. Only so much optimum barrel life.