I currently use RCBS standard dies for .308. I am planning on upgrading my equipment and thought about getting Matchmaster or Hornady equivalent bushing dies. I have been doing some reading here and elsewhere and it seems that getting consistent neck tension would result in tighter groups. I would assume the only way to get improve this would be to turn the necks on a latch or some sort; Hornady has a tool for this. Am I correct in assuming that turning the necks is the only way to get consistent tension and is there a better tool than the Hornady for this? I really don't want to have to add this step; though I would assume it would be a one and done for the life of the brass.
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Neck Tension
- Thread starter Buckeye Scott
- Start date
No, not one and done. Brass flows. It gets longer. That’s why there are trimmers. When brass flows, the shoulder becomes a part of the neck.
It’s one and done if you are shooting a cartridge with a sharp shoulder angle from a minimum chamber, like 6br or ppc, where brass does not expand very much.
Neck tension consistency is overrated. Good brass is good enough. You don’t have to turn it.
It’s one and done if you are shooting a cartridge with a sharp shoulder angle from a minimum chamber, like 6br or ppc, where brass does not expand very much.
Neck tension consistency is overrated. Good brass is good enough. You don’t have to turn it.
They already exist. You can buy force packs for most arbor presses.
I would agree that consistent neck tension is a key to smaller groups on target. I think annealing your brass after every firing contributes greatly to consistent neck tension. The other thing I like is to finish sizing using a mandrel die. I'm not ready to start neck turning.
But I'm not one of the top 100 shooters in the country either.
But I'm not one of the top 100 shooters in the country either.
I'm my own testing I've found that the right bushing does very well if you aneal the brass every time and use lapua brass. I've done the mandrel thing and I've not found it to be worth my time per the results on paper. A good bushing die and good annealing is how I roll these days and it works extremely well for me. The paper don't lie
Typically, when referring to "consistent neck tension" it has to do with the measurement of neck's OD after sizing and before seating a bullet and "inconsistency" is usually do to variations in springback as the neck work hardens after a number of firings due to variations in neck thickness from one case to another. If one is using something other than high quality brass, variations in neck thickness can be substantial, where turning the necks does help in this regard, but not so much with higher quality brass like Lapua. Turning necks for this consistency results in very, very small improvement at long distance if one is a top end competition shooter. For the rest of us, you're really not going to be able to see any difference. The thing that helps the most for "consistent neck tension" is annealing your brass often (like, I anneal after every firing and get very "consistent neck tension".
I don't like using bushing dies as they don't size the neck all the way down to the neck-shoulder junction. I prefer using a die without an expander ball and then expand the neck with an expander mandrel to get the neck OD that I'm after.
I agree with buying the bushing dies - they tend to work the brass much less (you're only moving it as much as necessary), turning high quality brass (Lapua in my case) yielded zero benefit (SDs were 5.4 to 5.7 of my non-turned brass shot the same day). Maybe cheaper brass would pick up some gains, but investing in good brass and quality match dies should get you where you're trying to go.
No. It's always shot in the same chamber and doesn't grow much at all but no, I don't turn brass
I think some guys try to get too much neck tension and that's what gives them trouble. I shoot for .0015" - .002" and I've tested if my bullets ever move ect and never had one move. You can't push them in or anything like that but they aren't hard at all to seat, I mean they almost feel like there's not much even there in the press and they all have the same feel when I seat them. I haven't don't any of the true seating pressure stuff because I don't need to. My SD and ES are low and my groups are tiny in every caliber I shoot. No reason to do anything more imo to get really great ammo. Using a quality bullet and bushing die with the right bump+ right size bushing, was my biggest revelation to getting truly consistent ammo.
My friend, have you mistakenly used “OD” when meaning “ID”.
As far as I can tell, neck tension is the delta between neck ID and bullet bearing surface OD.
And also, and I’m more than willing to be corrected, mandrel dare only concerned w ID. No?
I use a mandrel as my final step to get the exact neck tension I desire.
For the OP:
A lot of guys do it this way and have excellent results. It's really not a huge deal to do with a mandrel this way, I just didn't find it to show up on paper vs my bushing die only to set final neck tension diameter. If you do get a mandrel , don't get the cheap ones that require a bunch of lube, it's not worth it.
This. It’s not nearly as hard as some people make it seem. People will call you poor but the Lee collet die makes some of mine so consistent I sometimes have to check to see if the chrono is broken. We’ve got plenty of “super duper match grade die(s)” but I find myself grabbing the collet die all the time. I sanded down the mandrel to get the exact sizing I wanted and it’s like cheating. Call me poor but if it works it works
I don't know the answer on 308 as I just use regular RCBS dies and shoot the ammo in a factory built rifle. It shoots well under MOA so I have just left things alone.
In 223, using a mandrel made my groups shrink. I didn't see a big change when adding or subtracting .001 of neck tension. Bullet choice mattered more, the higher the quality, the better the groups.
In 223, using a mandrel made my groups shrink. I didn't see a big change when adding or subtracting .001 of neck tension. Bullet choice mattered more, the higher the quality, the better the groups.
while with little way to prove it I highly doubt it does that much , I have had good groups with looser neck tensions , and with a factory neck tensions . Both producing group equal to each other and sd's and es number than could have been mirrored . I have also taken my self out of the equation by strapping the gun to the table so nothing I did , did anything and groups were just as good either way they were obviously better cause non of my shakes or mistakes did not do a thing to influence anything . Your going to do which ever you want cause it's your preferences that matter when your shooting your gun . I still adjust my necks it's my preference , but they shoot just as good as factory rounds with a factory tight neck except through crimping your only ever going to get a neck so tight never heard of a neck so tight it crushed the bullet when you press it in the case . practice , classes and someone to point out what your doing correct and what your doing wrong help you get better thinking neck tension is going to make your groups magically fix your problems you create that just sounds like a long shot . Best of luck to you which ever you choose to do .
Most shooters who reload are actually competent reloaders however a lot of them over-think shit to death and obsess over stupid shit when in fact many can’t shoot to the potential of their own ammo on a consistent basis. So they over-analyze one thing or another and go down rabbit holes (or try to spend their way to success). Most of the time, if the ammo isnt “performing” the shooter is likely the problem (thats the first place i look, anyway).This. It’s not nearly as hard as some people make it seem. People will call you poor but the Lee collet die makes some of mine so consistent I sometimes have to check to see if the chrono is broken. We’ve got plenty of “super duper match grade die(s)” but I find myself grabbing the collet die all the time. I sanded down the mandrel to get the exact sizing I wanted and it’s like cheating. Call me poor but if it works it works
Nothing wrong with Lee dies. I used a set of Lees for years to load 6.8spc that would group .75-1 moa out of a woa match 16” ss barrel and was a laser to 500m w/110 accubonds.
.0015-.002 “neck tension” like BC LLC said, consistent shoulder bump, reasonably consistent charge weight (+- .15g) and CBTO and that’s really all i care about.
One thing i do advise people to do is keep one set of dies per firearm. Fuck constantly adjusting one die for multiple rifles of the same cartridge-that’s a potential source of issues no one needs.
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Neck tension is measured with OD. Measure before bullet is seated, measure after bullet is seated.
Pardon me, But is not neck tension defined as the difference between the ID of the neck and OD of the bullet. By definition...no?
If my neck ID is .2615 and my bullet OD is .2635 then I have .002" of neck tension.
What you suggest strikes me as a very indirect way to take what is otherwise a simple measurement and seems to utterly rely on absolutely consistent neck wall thickness (neck turning, right?)
Mandrels work from the inside to set neck ID. Pin gauges will tell me what neck ID I will have after spring back. Compare it to the bullet OD and is this not "neck tension".....really what the rest of the world would call an interference fit.
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bushing die and mandrel. oh and a set of pin guages will tell you the precise ID and they're only a couple bucks each on amazon.
Exactly. New reloaders read about the ocd category of processes and come away thinking it’s all really complicated.
You’re correct as to what neck tension is. I’m sure you could use a pin gauge and the OD of the bullet. I’ve just always seen it measured on the neck OD, one with and one without the bullet seated.
Wall thickness doesn’t matter bc the case is measured before the bullet goes in. It’s a relative measurement. I don’t neck turn and never pay a whole lot of attention to neck wall thickness, but I’m not sure the variation would be enough to affect seating unless you were using some pretty bad brass. I think guys who neck turn our shaving off 10 thousandths.
I don’t know about other people but I don’t measure neck tension on every round.
For me it’s something I set up when I start seating and then I roll with it unless something feels off in seating.
Agree with you description of what neck tension is. I was describing the easy way to measure it.
Again, my reference is to keep on point with regard to how I was describing the easy way to measure it.
Of course, if one doesn't want to do it the easy way, depending on the available tools to measure properly and do the math, then one only needs to be concerned with the neck's ID.
None of that is “neck tension”
Y’all are describing interference fit.
The difference between the inside and the outside variance is neck thickness. It doesn’t much matter which you do but outside is easiest to measure with calipers.
Tension is hard to measure and has many factors beyond simple interference fit but interference fit is the easiest and only one that people measure and so people just call that neck tension. I only measure that as well.
You can have to cases with the exact same interference fit but drastically different tension.
Y’all are describing interference fit.
The difference between the inside and the outside variance is neck thickness. It doesn’t much matter which you do but outside is easiest to measure with calipers.
Tension is hard to measure and has many factors beyond simple interference fit but interference fit is the easiest and only one that people measure and so people just call that neck tension. I only measure that as well.
You can have to cases with the exact same interference fit but drastically different tension.
For discussion and measuring sake it is neck tension though. Nobody measures friction or any of that so when you ask what tension someone is using they always give you a number in thousandths. Isn’t actual tension measured in newtons or lbs?
Actually neck tension (hoop stress) is what is left over after friction.
High friction/Low friction might contribute to FEEL or Press Seating Force.
Various Neck Lubes or HBN/Moly reduces FRICTION.
Anybody use neck lube?
Does it Reduce/Increase neck tension after you have seated the projectile?
For annealed brass in the neck, same thickness, same tensile strength from case to case, does stretching the neck by 0.002" diameter to fit over a bullet come closer to showing neck TENSION, regardless of FRICTION?
Now, what happens with FRICTION as the bullet leaves the room?
High friction/Low friction might contribute to FEEL or Press Seating Force.
Various Neck Lubes or HBN/Moly reduces FRICTION.
Anybody use neck lube?
Does it Reduce/Increase neck tension after you have seated the projectile?
For annealed brass in the neck, same thickness, same tensile strength from case to case, does stretching the neck by 0.002" diameter to fit over a bullet come closer to showing neck TENSION, regardless of FRICTION?
Now, what happens with FRICTION as the bullet leaves the room?
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Yeah in our short hand slang, sure, its the term we use for some reason.
But "is not neck tension defined as the difference between" and "you’re correct as to what neck tension is" is just not.
And yes, its a measure of force
But in the real world of reloading that’s exactly what it is. When someone asks what neck tension you’re running do you give them a measurement in newtons or a measurement in hundredths of an inch?
I was wondering about this. I think the accurate shooter article started this thing about neck tension being “how much force it takes to move the bullet from the case”. I’m no engineer and I could be way off but wouldn’t tension be the actual stress(or the force that acts on the bullet due to that stress) in the brass due to it being stretched? So if we wanted to calculate how much force it takes to unseat the bullet wouldn’t we have to look at tension and friction separately?
Annealed brass will relax a little over time under stress while work hardened will spring back.
That why they sell lubes and some use only the best one ( ask which lube is the best)
That why they sell lubes and some use only the best one ( ask which lube is the best)
I try to call it interference fit and give the corresponding measurements but I’m sure you can find where I have faulted plenty of times. I’ll make a more concerted effort to not use incorrect terminology going forwards, thanks.
@spife7980, my friend…since you quoted me I thought to point out this other part from the same post (and yes, I always must be right! ;-) haha)
But hey…I love a good pedantic discussion as much as anybody! ;-). Lol
But hey…I love a good pedantic discussion as much as anybody! ;-). Lol
I saw that too but I don’t feel that’s what was followed up upon in further conversation.
Yeah, I’m picking fly shit out of pepper, it’s the internet.
I’m with ya, brother. Just having a bit of fun on a boring day.
This is too long. Oh well.
I use Redding or Wilson full length dies with a button. For 308 and 300 PRC, the button leaves the neck ID at about .303. I mandrel up to .305. The bullets are .308. After seating the bullets, the neck ID is the same as the bullet. After reading this thread, I no longer know what to call that
For me, the button makes the outside of the neck a cylinder. But I have "dreaded donuts" so the ID is not a cylinder. When I pin gauge the ID, a .303 gauge goes in part way until it hits the donut. The mandrel pushes the donut out and makes the inside of the neck a cylinder (well it tries and mostly succeeds). After mandrel, the .305 pin gauge fits smoothly but it won't drop into the case - friction holds it in place. By feel I can tell that the neck is mostly cylindrical.
Regarding "the button doesn't size the entire neck" - it is true, does it matter? The sized part is a consistent length (after trimming) and diameter (after sizing and mandrel). Some of the extra donut brass can live in the unsized part. Being larger, the unsized part helps to center the neck in the chamber - I think that is important, you mileage may vary. If you mandrel for smooth and consistent ID, what is the value of having the whole neck grip the bullet versus nine tenths of it? A 300 win mag has a neck less than one caliber long, maybe it would help there. For other calibers? It is your call. What shows up on the paper? I suck enough that I can't see it on targets.
Neck thickness and turning - most brass has a neck thickness around 15 thou. Good brass is consistent all the way around. Lapua is pretty good, most other brass is not that good (Use a tube mic to check). As a former BR shooter, we necked up 22 PPC Lapua brass to make 6 PPC. Neck turning was necessary for two reasons, the chamber had a tight neck so necked up brass would not fit in the chamber. After mandreling up to about .243 ID, the neck walls were not uniform. Most everyone I knew was shooting a .262 neck so we turned to about 0.0085 neck thickness. With a .243 bullet you ended up with a .260 OD or about a thou on each side of the neck - back in the day that was normal. Some people went a little tighter, some a little looser. A .009 neck thickness did not always chamber quickly in a gun with dirty neck and that risked pressure and a shot out of the group. A .008 neck yielded a .259 neck OD, plenty good.
A side comment on tight necks. Both of my 6 PPC guns had .262 necks. With .243 bullets, that leaves a total of .019 or .0095 thickness. In the SAAMI chamber for 243 winchester the neck ID is .277 - that is enough room for brass with .017 neck thickness.
When I was shooting 300 win mag, even on good brass, neck thickness was not uniform. With bad brass the variation could be 3 or 4 thou. The normal starting thickness was about .015. I turned a bunch of necks taking between .002 and .005 off the thickness. A couple years ago I sorted my 300 WM brass by neck thickness. I have necks from .010 to .013. The problem with that is: I have to know the neck thickness in order to select the correct button when sizing. If I don't get the right button, the bullet falls into the case. On balance:
I use Redding or Wilson full length dies with a button. For 308 and 300 PRC, the button leaves the neck ID at about .303. I mandrel up to .305. The bullets are .308. After seating the bullets, the neck ID is the same as the bullet. After reading this thread, I no longer know what to call that
For me, the button makes the outside of the neck a cylinder. But I have "dreaded donuts" so the ID is not a cylinder. When I pin gauge the ID, a .303 gauge goes in part way until it hits the donut. The mandrel pushes the donut out and makes the inside of the neck a cylinder (well it tries and mostly succeeds). After mandrel, the .305 pin gauge fits smoothly but it won't drop into the case - friction holds it in place. By feel I can tell that the neck is mostly cylindrical.
Regarding "the button doesn't size the entire neck" - it is true, does it matter? The sized part is a consistent length (after trimming) and diameter (after sizing and mandrel). Some of the extra donut brass can live in the unsized part. Being larger, the unsized part helps to center the neck in the chamber - I think that is important, you mileage may vary. If you mandrel for smooth and consistent ID, what is the value of having the whole neck grip the bullet versus nine tenths of it? A 300 win mag has a neck less than one caliber long, maybe it would help there. For other calibers? It is your call. What shows up on the paper? I suck enough that I can't see it on targets.
Neck thickness and turning - most brass has a neck thickness around 15 thou. Good brass is consistent all the way around. Lapua is pretty good, most other brass is not that good (Use a tube mic to check). As a former BR shooter, we necked up 22 PPC Lapua brass to make 6 PPC. Neck turning was necessary for two reasons, the chamber had a tight neck so necked up brass would not fit in the chamber. After mandreling up to about .243 ID, the neck walls were not uniform. Most everyone I knew was shooting a .262 neck so we turned to about 0.0085 neck thickness. With a .243 bullet you ended up with a .260 OD or about a thou on each side of the neck - back in the day that was normal. Some people went a little tighter, some a little looser. A .009 neck thickness did not always chamber quickly in a gun with dirty neck and that risked pressure and a shot out of the group. A .008 neck yielded a .259 neck OD, plenty good.
A side comment on tight necks. Both of my 6 PPC guns had .262 necks. With .243 bullets, that leaves a total of .019 or .0095 thickness. In the SAAMI chamber for 243 winchester the neck ID is .277 - that is enough room for brass with .017 neck thickness.
When I was shooting 300 win mag, even on good brass, neck thickness was not uniform. With bad brass the variation could be 3 or 4 thou. The normal starting thickness was about .015. I turned a bunch of necks taking between .002 and .005 off the thickness. A couple years ago I sorted my 300 WM brass by neck thickness. I have necks from .010 to .013. The problem with that is: I have to know the neck thickness in order to select the correct button when sizing. If I don't get the right button, the bullet falls into the case. On balance:
- It made resizing tricky,
- I don't think I got any advantage (accuracy or otherwise) from turned necks,
- it is a pain in the ass,
- in a SAAMI chamber, it increases the space around the neck,
- If you create a gun with a tight neck, you can't shoot factory ammo in it.
- once turned, you can't put the brass back.
The force to overcome friction (unseat the bullet) is a function of the surface area, the coefficient of friction between the two surfaces, and the perpendicular force exhibited surface to surface. What people in reloading typically call neck tension, and others are calling interference fit, drives the force component. Neck lube (or not), residual carbon (or not), brass makeup, etc. all make up the coefficient of friction. Bullet seating depth may drive the surface area, though in most circumstances it does not come into play.
How do you measure? The closest analog we have is seating force using an arbor press for seating. I've done a fair amount of testing and have found a definitive correlation between seating force consistency and velocity consistency.
The components that yielded the best SDs were:
1) Using a bushing that yields an ID that minimally engages the mandrel - but still does engage every time.
2) Using a mandrel (as is obvious from step 1).
3) Using graphite neck lube.
I've got a thread called "Mandrel Musings" where I compare all of the combinations of using, or not using, the above steps. I measure both seating force consistency and muzzle velocity for each permutation.
