Surprising neck tension test ... (at least it surprised me)

[Yondering]

i think those indicators measure distance of spring contraction.

Ok. That would be spring rate then. Usually it’d be lb/in rather than in/lb (you can invert it of course but it’ll be a weird small number) but an easy enough mistake. But for a spring on a gauge that’ll be a constant number, and not a measure of the force on a bullet.

Like a 70 lb/in spring - compress it 1/2 inch and you’ve got 30 lb force, but the spring is still 70 lb/in.

 

[Cascade Hemi]

Say what now? Lol.

In-lb would be 1/12 of a ft-lb, not 1/12 of a lb. Neither one are measuring force, that’s a torque measurement.

Besides, the guy I replied to used in/lb, totally different than in-lb or lb force. Those units all mean different things and can’t just be converted to each other.

This is the internet, you've come to the wrong place if you expect factual information. Reloading is the multiple of anecdote and now you have the Google of engineering. Good day, sir!

 

[Yondering]

This is the internet, you've come to the wrong place if you expect factual information. Reloading is the multiple of anecdote and now you have the Google of engineering. Good day, sir!

Ok, if you meant that first post as sarcasm or humor then you got me; I missed that.

But no, there’s plenty of factual info here once you wade through the people throwing out made up bs. I think Dave62677 had some great info, I’d just like clarification on his units, whether he meant something else or just a repetitive typo.

 

[Cascade Hemi]

Ok, if you meant that first post as sarcasm or humor then you got me; I missed that.

But no, there’s plenty of factual info here once you wade through the people throwing out made up bs. I think Dave62677 had some great info, I’d just like clarification on his units, whether he meant something else or just a repetitive typo.

Thanks for letting us all know. Rusty appreciates your input.

 

[rustyinbend]

UPDATE ... (you're gonna want to read this)

So I got my Arbor Press with Force Pack and Dial Indicator today, along with the five caliber Inline Seater Dies that I ordered. HOLY CRAP ... was I surprised when I got to testing my standard loads.

Here's my advice to you guys ... the "feel" of the lever on a standard reloading press is IN NO WAY an accurate measure of seating force or neck tension. I started with my 6.5-CM load, which I've been refining so it "felt" like I was getting good neck tension ... vs. the greased slide feel when using the recommended size bushing and mandrel. I had started with that months ago and it just felt like there was "zero" force required to seat, so I've been ratcheting down the bushing and mandrel sizes to get some semblance of light pressure on the ram as I was seating bullets.

WRONG ANSWER !!!

I tried my current 6.5-CM load ... .284 bushing and .2610 mandrel ... that "felt" right when seating bullets on my single-stage press. When measured on my new arbor press, that load "started" to seat at 40 lbs of force, and on the high side the reading never registered because the press screws started to slide as I passed 100 lbs of force. I was stunned.

Decided to do all my measurements again ... .289 bushing and .2640 mandrel. Got a start force at 10 lbs and finish at around 15 lbs ... which was a little too light. Dialed down to a .288 bushing and a .2630 mandrel ... and got a perfect seating pressure start of about 15 lbs and a finish at about 25 lbs ... almost exactly where I wanted it (and thought it was before measuring properly).

Then I took this prepped case recipe (15 lbs / 25 lbs) over to my single-stage press that I've been using all along, and it felt like the bullet was sliding in unobstructed on greased skids.

Lessons learned:

1. If you care about neck tension ... buy the tools to measure it accurately.
2. Seating by "feel" on a regular press is a waste of time and supplies.
3. You're way closer to proper neck tension with the standard numbers ... than by trying to "feel" it on a standard press.

This has truly been an eye-opening exercise ... and now I need to go retool my reference loads and test them all again with the proper neck tension ... vs. the "hammered in" force I've been unwittingly using.

If I'm stupid and some of you say "No shit dumbass" ... then so be it. But irrespective of that ... these results really surprised me, and I'm glad I now "measure" instead of "feel" neck tension.

 

[SanPatHogger]

UPDATE ... (you're gonna want to read this)

So I got my Arbor Press with Force Pack and Dial Indicator today, along with the five caliber Inline Seater Dies that I ordered. HOLY CRAP ... was I surprised when I got to testing my standard loads.

Here's my advice to you guys ... the "feel" of the lever on a standard reloading press is IN NO WAY an accurate measure of seating force or neck tension. I started with my 6.5-CM load, which I've been refining so it "felt" like I was getting good neck tension ... vs. the greased slide feel when using the recommended size bushing and mandrel. I had started with that months ago and it just felt like there was "zero" force required to seat, so I've been ratcheting down the bushing and mandrel sizes to get some semblance of light pressure on the ram as I was seating bullets.

WRONG ANSWER !!!

I tried my current 6.5-CM load ... .284 bushing and .2610 mandrel ... that "felt" right when seating bullets on my single-stage press. When measured on my new arbor press, that load "started" to seat at 40 lbs of force, and on the high side the reading never registered because the press screws started to slide as I passed 100 lbs of force. I was stunned.

Decided to do all my measurements again ... .289 bushing and .2640 mandrel. Got a start force at 10 lbs and finish at around 15 lbs ... which was a little too light. Dialed down to a .288 bushing and a .2630 mandrel ... and got a perfect seating pressure start of about 15 lbs and a finish at about 25 lbs ... almost exactly where I wanted it (and thought it was before measuring properly).

Then I took this prepped case recipe (15 lbs / 25 lbs) over to my single-stage press that I've been using all along, and it felt like the bullet was sliding in unobstructed on greased skids.

Lessons learned:

1. If you care about neck tension ... buy the tools to measure it accurately.
2. Seating by "feel" on a regular press is a waste of time and supplies.
3. You're way closer to proper neck tension with the standard numbers ... than by trying to "feel" it on a standard press.

This has truly been an eye-opening exercise ... and now I need to go retool my reference loads and test them all again with the proper neck tension ... vs. the "hammered in" force I've been unwittingly using.

If I'm stupid and some of you say "No shit dumbass" ... then so be it. But irrespective of that ... these results really surprised me, and I'm glad I now "measure" instead of "feel" neck tension.

So in the beginning you found that heavy neck tension shot better than light. But now the gauge maxes out so you are going lighter again?

If you read about the lee factory crimp die, the crimp acts like loading OAL to the lands and allows the pressure to rise some before letting the bullet go, giving a more even powder burn.
I dont know if it really works. Just reading what youv'e posted and thinking about what's going on.

 

[rustyinbend]

So in the beginning you found that heavy neck tension shot better than light. But now the gauge maxes out so you are going lighter again?

If you read about the lee factory crimp die, the crimp acts like loading OAL to the lands and allows the pressure to rise some before letting the bullet go, giving a more even powder burn.
I dont know if it really works. Just reading what youv'e posted and thinking about what's going on.

What I'm doing now is reloading some tests with "reasonable" neck tension ... and shooting them for SD and Groups to compare with the ultra-heavy neck tension I've been inadvertently running. I'll see where it leads me next.

 

[MarkyMark007]

imho
dont go over 0.003' of 'neck tension' because 0.002' is 'theoretical' maximum. over that value you are deforming your brass with no additional tension, and your bullet jacket can be deforming. if this is true: https://bisonballistics.com/articles/case-neck-tension-a-stress-analysis

and ask producer of your press (K&M I suppose), if your values of force is comperable to other K&M presses. maybe they are, but maybe they are not!
is force the same at different speed? is force the same at different height?

and I think the force is NOT the same in your press and 21century hidraulic press...

so be careful when comparing your data to others!

 

[Yondering]

imho
dont go over 0.003' of 'neck tension' because 0.002' is 'theoretical' maximum. over that value you are deforming your brass with no additional tension, and your bullet jacket can be deforming. if this is true: https://bisonballistics.com/articles/case-neck-tension-a-stress-analysis

Not true. Read the second to last paragraph in that article; they even say so. If staying inside the elastic limit means lower neck tension than most of us use, then obviously neck tension is still increased as we go beyond the elastic limit.

"Other practical concerns pop up as well. Staying below the elastic limit means using what most shooters consider to be very light neck tension - maybe even too light to reliably hold the bullet. While this may be fine for certain rifle setups (like benchrest), it's not acceptable for hunting or PRS competition."


But to Rustyinbend - IMO you may be going at this backwards. Instead of deciding ahead of time what seating force value is the correct target, you'll have better results to see what shoots best, and use that as your seating force target. If the one that shoots best is off the scale, as you said, then that scale is probably made for a different application than you're using it for. Don't let the tool drive you to chase something different than what shoots best in your rifle.

 

[MarkyMark007]

Not true. Read the second to last paragraph in that article; they even say so. If staying inside the elastic limit means lower neck tension than most of us use, then obviously neck tension is still increased as we go beyond the elastic limit.

you are right.
if brass is not annealed, it is more elastic, and larger spring backs are possible.

 

[rustyinbend]

But to Rustyinbend - IMO you may be going at this backwards. Instead of deciding ahead of time what seating force value is the correct target, you'll have better results to see what shoots best, and use that as your seating force target. If the one that shoots best is off the scale, as you said, then that scale is probably made for a different application than you're using it for. Don't let the tool drive you to chase something different than what shoots best in your rifle.

Good advice. I'm using the tool to tell me something I didn't know, and measure something that I couldn't before. I've built some tests with varying (but reasonable) seating force and neck tension, and am headed to the range on Thursday to see how it performs in group tests. I'm super-interested to see what it does to my velocity, and if it improves groups compared to results from my mega-high neck tension. At the end of the day, what matters is (a) group size, and (b) accuracy at distance.

 

[MarkyMark007]

velocity spread is the most important thing at accuracy at distance, not group size. imho.

 

[rustyinbend]

velocity spread is the most important thing at accuracy at distance, not group size. imho.

I feel like they're equally important, as both will cause misses at distance. Great SD's that don't hit the target, aren't especially helpful ... and tight groups at 100 yards that have velocity all over the map and can't hit consistently at 1000 also aren't much good.

 

[Dave62677]

Understand your misses will lead you to great success. Be caution and don’t over look with your grip, trigger finger placement, bipod load pressure , recoil directions. Just being consistent of all above , you will be fine.

 

[rustyinbend]

Understand your misses will lead you to great success. Be caution and don’t over look with your grip, trigger finger placement, bipod load pressure , recoil directions. Just being consistent of all above , you will be fine.

I find when I totally concentrate on all those things, especially sight picture, breathing and trigger pull, and block-off the outside world ... groups are awesome. When I'm not ... they're not.

 

[Govt Mule]

and ask producer of your press (K&M I suppose), if your values of force is comperable to other K&M presses. maybe they are, but maybe they are not!
is force the same at different speed? is force the same at different height?

and I think the force is NOT the same in your press and 21century hidraulic press...

It doesn't matter if his numbers are different than anyone elses press. Regardless of the number, if everything is being done on this press for a given caliber, he will get a solid number that he can count on. If he was doing some on a 21st Century, and the rest on his K&M, it would matter.

 

[Govt Mule]

velocity spread is the most important thing at accuracy at distance, not group size. imho.

I disagree, and every benchrest shooter will disagree with you as well.

 

[nick338]

velocity spread is the most important thing at accuracy at distance, not group size. imho.

You can have good SD's and shitty groups at distance. Seen it many times with a seating depth that the bullet doesn't like. Great groups at 100 turn to shit at longer range with tons of vertical yet the SD at 100 is great. Everything is equally important at distance.

 

[Govt Mule]

You can have good SD's and shitty groups at distance. Seen it many times with a seating depth that the bullet doesn't like. Great groups at 100 turn to shit at longer range with tons of vertical yet the SD at 100 is great. Everything is equally important at distance.

Jim Borden and I had a conversation years ago about SD & ES. I was trying to argue that the CCI BR2 primer was better because it gave me better SD's than the 210M. His only point was which one gave the tightest groups. He didn't care about SD's/ES's, and he was a multiple world champion in benchrest.
You have to test everything at the distances you will be competing at to trust that they will perform. If you are shooting 1000 yards, you can't test your loads at 100 yards and expect them to perform the same.

 

[nick338]

Jim Borden and I had a conversation years ago about SD & ES. I was trying to argue that the CCI BR2 primer was better because it gave me better SD's than the 210M. His only point was which one gave the tightest groups. He didn't care about SD's/ES's, and he was a multiple world champion in benchrest.
You have to test everything at the distances you will be competing at to trust that they will perform. If you are shooting 1000 yards, you can't test your loads at 100 yards and expect them to perform the same.

100% True. I probably waste a lot of time and components shooting too much at 100 but I like to have a direction to go in before I hit longer ranges to fine tune a load.

 

[Yondering]

velocity spread is the most important thing at accuracy at distance, not group size. imho.

I can't agree with that, when using the qualifier "at distance".

Hitting the target is the #1 most important thing, obviously. At distance, meaning whatever you're shooting at, accuracy is what makes that happen. Velocity spread doesn't mean crap if you don't have the accuracy. And if your accuracy at distance is good, then it doesn't matter what your velocity spreads are, you've already accomplished the goal of being able to hit the target.

 

[Cascade Hemi]

Good advice. I'm using the tool to tell me something I didn't know, and measure something that I couldn't before. I've built some tests with varying (but reasonable) seating force and neck tension, and am headed to the range on Thursday to see how it performs in group tests. I'm super-interested to see what it does to my velocity, and if it improves groups compared to results from my mega-high neck tension. At the end of the day, what matters is (a) group size, and (b) accuracy at distance.

All that matters is controlling variables. If your best group takes 90lbs to seat then all of the loaded cartridges need to take the same force. The purpose of the tool is to help identify variation, not dictate the ideal pressure.

 

[MarkyMark007]

Jim Borden and I had a conversation years ago about SD & ES. I was trying to argue that the CCI BR2 primer was better because it gave me better SD's than the 210M. His only point was which one gave the tightest groups. He didn't care about SD's/ES's, and he was a multiple world champion in benchrest.
You have to test everything at the distances you will be competing at to trust that they will perform. If you are shooting 1000 yards, you can't test your loads at 100 yards and expect them to perform the same.

he didnt care about SD because he shoots benchrest. in F-Class with SD of 20fps you cant seriously compete, because only with this alone you will have vertical of 1.5+MOA.

and primers... in every cartridge it is different. every lot of primers are different. to some cartridge and powder combination it is better BR2 and some GM210M and some Sellier & Bellot.
people should try different primers to see what works the best for them.

 

[MarkyMark007]

but yes, groups must be very good also.
but I am more focusing about velocity spread than for the groups at 1000m. if group isnt 0.5 MOA and it's 0.6 MOA on 1000m, it is a win for me personaly.
but for SD of velocity I am trying to do my best. I am also waiting for rusty's report of mandrels, if I should use them

 

[Haney]

Do these F-Class matches go by velocity alone , or do you have to hit something with the bullet ?

 

[iceng]

In my small sample sizes i find it to be cartridge dependent. My 223ai like heavy tension, 6.5cm moderate, and 6br my groups tightened way up by decreasing tension. Ymmv

Ok, i have a theory based on this. And this is a WILD guess just from what you said.

"Long powder column cartridges like tigher necks, and shorter fatter cases like minimum".

223wssm ? Id guess minimal. 30-06, probably on the tighter side.

Hmmm,. I smell an experiment.. where youtubes "bolt action reloading" guy. He does some excellent data sets.

 

[MarkyMark007]

bryan litz analized 223rem, 243win and 308win with 0.001' and 0.003' neck tension. 0.003' were better in 223rem and 243win, but 308win the same.

 

[Govt Mule]

he didnt care about SD because he shoots benchrest. in F-Class with SD of 20fps you cant seriously compete, because only with this alone you will have vertical of 1.5+MOA.

Jim DOES care about what primers he shoots. He tested every brand available to him, and found the Federal primers shot the tightest in his chamberings and barrels. He just doesn't worry about SD's.

I compete in F-open on a national level and agree with you on the need to minimize vertical dispersion.
Cheers

 

[MarkyMark007]

He just doesn't worry about SD's.

because if you have tight vertical at 1000m, you automaticly have good SD and you dont care about it.
but if you develope load only at 100m, you must see how much is your SD.

 

[Yondering]

because if you have tight vertical at 1000m, you automaticly have good SD and you dont care about it.
but if you develope load only at 100m, you must see how much is your SD.

You seem to be missing the meaning of the words “at distance” when we said “accuracy at distance” earlier.

 

[rustyinbend]

OP UPDATE - 10/04/2022

Well ... a lot has gone on here since I started this thread. I've tested a LOT of stuff now that I have a means of knowing exact neck tension and seating force. It's all about swinging the right tool ... eh? This documents one result that surprised me. As I've gotten closer to what I consider the "perfect" neck tension with my Barrett MRAD 300-PRC, I decided to try a 10-round test, where the ONLY difference was that the first group used a .3070 Mandrel, and the second group opened the neck slightly more with a .3080 mandrel. The first had a much higher max seating force (almost 80 lbs), and the second had a much lighter max seating force (around 40 lbs). Both gave solid results, but the smaller neck tension provided a Standard Deviation of about "half" the larger mandrel. .3070 mandrel SD was 3.96 and the .3080 mandrel SD was 7.94 ... with the averages very close and the ES' following the SD's. Not a surprise that at 100 yards, both delivered very tight groups.

Is anyone else surprised by these results of almost "double" the SD for only a 1/1000th larger mandrel, with no statistical change in velocity?

I was a little surprised by this.

Like the guy on the Bolt Action Reloading YouTube says ... "In God we trust - All others bring data."

Next test is with a .3075 mandrel to see if it splits the difference, or delivers a surprise result.

 

[Cascade Hemi]

Try the same test with .005" of interference.

 

[rustyinbend]

Try the same test with .005" of interference.

I don't know what that means. How do I induce "interference" ... and if I do, will the Referee throw a yellow flag at me?

 

[Cascade Hemi]

I don't know what that means. How do I induce "interference" ... and if I do, will the Referee throw a yellow flag at me?

Interference is the difference between the ID of the case and OD of the bullet. I know what mandrels you are using but I don't know the finished ID of your brass since you didn't state it. Anyway, keep going smaller ID until your load starts to fall apart.

 

[spife7980]

I’d also repeat it. You might have the inverse results next weekend.

 

[rustyinbend]

Interference is the difference between the ID of the case and OD of the bullet. I know what mandrels you are using but I don't know the finished ID of your brass since you didn't state it. Anyway, keep going smaller ID until your load starts to fall apart.

I still don't get it. Isn't that what I'm doing when I reduce the size of the mandrel ... inducing more pressure (aka: interference)? Wouldn't the ID be the mandrel size, minus springback?

 

[spife7980]

I still don't get it. Isn't that what I'm doing when I reduce the size of the mandrel ... inducing more pressure (aka: interference)? Wouldn't the ID be the mandrel size, minus springback?

Yes sorta but we don’t know how thick your brass is and how much spring back etc. You are telling us the tool but not the resultant measurements is what he’s getting at.

 

[MarkyMark007]

Is anyone else surprised by these results of almost "double" the SD for only a 1/1000th larger mandrel, with no statistical change in velocity?

no.
brian litz also says that he didnt get significant difference in velocity.

but some calibers get better SD with higher tension.

 

[MarkyMark007]

Next test is with a .3075 mandrel to see if it splits the difference, or delivers a surprise result.

the most stupid thing to do. splitting hairs with 0.0005' increment...

but if you do, dont forget to test ALSO .307 and .308, so you can compare them with previous results.

and try to shoot one-per-one; one .307 than one .3075 than one .308 than one .307 etc... maybe this will be better for real velocity because barrel condition...

 

[Haney]

the most stupid thing to do. splitting hairs with 0.0005' increment...

but if you do, dont forget to test ALSO .307 and .308, so you can compare them with previous results.

and try to shoot one-per-one; one .307 than one .3075 than one .308 than one .307 etc... maybe this will be better for real velocity because barrel condition...

That's funny right there . You say "most stupid" , yet you give details of how to run that test .

 

[rustyinbend]

That's funny right there . You say "most stupid" , yet you give details of how to run that test .

I thought that was odd too, but I was trying to be polite.

 

[Haney]

I still don't get it. Isn't that what I'm doing when I reduce the size of the mandrel ... inducing more pressure (aka: interference)? Wouldn't the ID be the mandrel size, minus springback?

This is 100 percent correct .

 

[Haney]

I thought that was odd too, but I was trying to be polite.

Polite ? I give respect when it's due , that rarely happens in this sub-forum .

 

[MarkyMark007]

I thought that was odd too, but I was trying to be polite.

and i will laugh later...

 

[jsthntn247]

OP UPDATE - 10/04/2022

Well ... a lot has gone on here since I started this thread. I've tested a LOT of stuff now that I have a means of knowing exact neck tension and seating force. It's all about swinging the right tool ... eh? This documents one result that surprised me. As I've gotten closer to what I consider the "perfect" neck tension with my Barrett MRAD 300-PRC, I decided to try a 10-round test, where the ONLY difference was that the first group used a .3070 Mandrel, and the second group opened the neck slightly more with a .3080 mandrel. The first had a much higher max seating force (almost 80 lbs), and the second had a much lighter max seating force (around 40 lbs). Both gave solid results, but the smaller neck tension provided a Standard Deviation of about "half" the larger mandrel. .3070 mandrel SD was 3.96 and the .3080 mandrel SD was 7.94 ... with the averages very close and the ES' following the SD's. Not a surprise that at 100 yards, both delivered very tight groups.

Is anyone else surprised by these results of almost "double" the SD for only a 1/1000th larger mandrel, with no statistical change in velocity?

I was a little surprised by this.

Like the guy on the Bolt Action Reloading YouTube says ... "In God we trust - All others bring data."

Next test is with a .3075 mandrel to see if it splits the difference, or delivers a surprise result.

View attachment 7970246

Rusty, have you measured and shot the difference In seating force and sd with different lubes or no lube in the neck. Try some powder graphite you dip the neck I , spray dry film graphite applied with a qtip, and no lube/leaving powder residue in the case neck. I’ve done this and it has a huge effect on es/sd and seating force. Everything else being equal seating force can vary 30lb with one lube to the next. Also consistency in seating force varied greatly. In my findings you want as slick of an inside of the neck as possible so your not measuring friction of the bullet to the neck and your measuring squeeze of the neck to the bullet when changing different bushings and mandrel.

 

[MarkyMark007]

Rusty, have you measured and shot the difference In seating force and sd with different lubes or no lube in the neck. Try some powder graphite you dip the neck I , spray dry film graphite applied with a qtip, and no lube/leaving powder residue in the case neck. I’ve done this and it has a huge effect on es/sd and seating force. Everything else being equal seating force can vary 30lb with one lube to the next. Also consistency in seating force varied greatly. In my findings you want as slick of an inside of the neck as possible so your not measuring friction of the bullet to the neck and your measuring squeeze of the neck to the bullet when changing different bushings and mandrel.

and why you need to have the same seating force?

 

[jsthntn247]

and why you need to have the same seating force?

I had knowledgeable response for you but after reading your response to the OCW thread your not worth the time and just a fucking retard or a troll.

 

[Lawnboi]

Good info. I started with an arbor press and learned very quickly what worked and what didn’t for bushings mandrels. As you pointed out what feels easy on a press, is too much on a arbor press.

Seating on the arbor press Is real quick too. I don’t have a force pack but if I notice one is more or less by feel I set it aside for a practice round.

 

[Yondering]

and why you need to have the same seating force?

Are you Russian, or some sort of eastern European with english as a second language? You seem to have some significant communication issues here, with a lot of things you don't understand due to language issues from what I can tell.

The problem is you don't seem to realize how much of this you don't understand, and are acting like you know a lot more than you really do.

 

[MarkyMark007]

Are you Russian, or some sort of eastern European with english as a second language? You seem to have some significant communication issues here, with a lot of things you don't understand due to language issues from what I can tell.

The problem is you don't seem to realize how much of this you don't understand, and are acting like you know a lot more than you really do.

i understand everything, but you dont understand a lot.
but not because my language, but because you are not smart. i know that this is something you dont understand...