Best way to do a neck tension test ... with the fewest supplies

rustyinbend

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    I'm at the "fine-tuning" point in load development for a couple of my precision rifles, and want to do a neck-tension test with a minimum of supplies (bullets, primers, powder). Looking for the best way to optimize supplies, and still get a good test. I use a Redding FL Type S sizing die with a whole bunch of different internal bushings available, and the 21st Century full expander mandrel set ... so I have the hardware to do any combinations I want to test. My quandary is that testing a bunch of combinations (bushing alone, mandrel alone, bushing/mandrel combo, mandrel first then bushing, bushing first then mandrel, etc.) will take a ton of time and a bunch of supplies. Anybody got a "best practice" method that can get this done in 15-to-20 rounds? BTW ... I'm not "unhappy" with current neck tension and I'm getting smooth bullet seating with acceptable SD's ... but I just want to make sure I can't invest a little time and get even better results. (Note: I wish I had a way other than "feel" to measure seating pressure, but I don't.)

    Left to my own devices, I'd probably "size down" with a relatively compact bushing size, and then do multiple 3-shot group tests "sizing up" with the five different mandrel sizes above and below what I'm currently using to test for both SD and group sizes. Am I on the right track ... or is there a better way to do this using 20-ish rounds?
     
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    JoshPutman

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    Now just to be clear, I have no experience with the equipment you've mentioned for sizing necks. That being said, I wonder if loading one round with each setting and shooting a group, being observant of where each round impacts, along with the velocity, would work.

    If the group was nice and tight, it would show that the difference in each round made pretty much no difference. However, a large group would show the opposite, and tracking potential sweet spots, like maybe two rounds that had similar tension and impacted closer together than other rounds. Kind of like a ladder test, if I understand that process correctly.

    I hope this made sense.
     

    TheOfficeT-Rex

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    Now just to be clear, I have no experience with the equipment you've mentioned for sizing necks. That being said, I wonder if loading one round with each setting and shooting a group, being observant of where each round impacts, along with the velocity, would work.

    If the group was nice and tight, it would show that the difference in each round made pretty much no difference. However, a large group would show the opposite, and tracking potential sweet spots, like maybe two rounds that had similar tension and impacted closer together than other rounds. Kind of like a ladder test, if I understand that process correctly.

    I hope this made sense.

    I thought this would be silly - then I got to the second paragraph. Interesting take, using it as a null hypothesis. I don't think you could use it for any sweet spots, but you could use it to prove that it may be wasted time investigating further (goal dependent, of course - this could work for precision, but not necessarily for finding the best chrono numbers).

    ETA - OP, I'm over using single groups or small round count tests to find the best precision - I'm not happy unless it's repeating. If you're just trying to get 'good enough' without using the rounds to test and verify, you may be at 'good enough' already.
     

    rustyinbend

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    Now just to be clear, I have no experience with the equipment you've mentioned for sizing necks. That being said, I wonder if loading one round with each setting and shooting a group, being observant of where each round impacts, along with the velocity, would work.

    If the group was nice and tight, it would show that the difference in each round made pretty much no difference. However, a large group would show the opposite, and tracking potential sweet spots, like maybe two rounds that had similar tension and impacted closer together than other rounds. Kind of like a ladder test, if I understand that process correctly.

    I hope this made sense.
    Interesting idea, but kind of an argument for the scenario I described I was leaning towards ... with 3-shot groups testing neck tensions above and below my currently well-performing load. I'm not good enough of a shooter to draw any inference from a single shot (or even 2).
     
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    rustyinbend

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    I thought this would be silly - then I got to the second paragraph. Interesting take, using it as a null hypothesis. I don't think you could use it for any sweet spots, but you could use it to prove that it may be wasted time investigating further (goal dependent, of course - this could work for precision, but not necessarily for finding the best chrono numbers).

    ETA - OP, I'm over using single groups or small round count tests to find the best precision - I'm not happy unless it's repeating. If you're just trying to get 'good enough' without using the rounds to test and verify, you may be at 'good enough' already.
    That's a good point ... when is "good enough" ... good enough? I've always struggled with that question. Maybe the answer is more simple ... "It's 'good enough', when you can consistently repeat it."
     
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    TheOfficeT-Rex

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    That's a good point ... when is "good enough" ... good enough? I've always struggled with that question. Maybe the answer is more simple ... "It's 'good enough', when you can consistently repeat it."

    I'd propose it's goal dependent - which I don't think you laid out. Are you after smallest groups? PRS match loads? ELR matches? Tinkering because it's fun?

    Plan from the objective backwards - you may be there, or you may need a full box of test rounds.
     
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    HMRamateur

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    Your experience might not match mine, but I no longer use a bushing or expander button when sizing brass. Just a pass through the full length minus the expander button, then a pass through the mandrel die.

    I had good groups using all methods, and I had awesome groups using all methods, but the biggest improvement I found was with the mandrel and that was to my SD/ES. Using the button and bushing I felt was just an unnecessary step of working the brass to end up at the same place I ended up anyway. Once you go through your testing, try this method and see how it works for you.
     
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    2aBaCa

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    at this point you really need a way to actually measure neck tension and changes your process are producing. otherwise its really a more or less shot in the dark. an arbor press with a guage would be best. least expensive would be a few guage pins that will let you measure internal dimentions and you can sort from there.
     

    canezach

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    If I may, in my experience neck tension has had an extremely minimal effect on group size, albeit that's only been tested with 0.001" and 0.002" tensions, since those are the only two mandrels I have for each caliber. Both groups were more than acceptable and I may have been the difference between the two. I haven't tried any of the other mandrels that offer an extra 0.0005" of tension, so take it for what it's worth. The effect that was noticeable, but again small, was in SD and ES. I'm not at home so I don't have my notebook in front of me, but for me 0.001" if neck tension was slightly better in both areas, but again, the difference was small, like maybe 0.5 for SD and 1 to 2 MPH for ES.

    I use a Redding Type S die with a bushing that is 0.003" smaller than my seated neck diameter and then run the brass through my mandrel. As with everything else, YMMV
     
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    Buckley

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    Through my research I believe that the only true way to achieve consistent neck tension when using bushing dies is to first neck turn the brass. I have been loading with a bushing up to now without turning and haven’t had any issues but have noticed somewhat differing seating pressures at times. I just yesterday started to process a batch of brass using a collet/mandrel neck only sizing die, no bushing used at all. Will charge and seat later today and am looking forward to how the seating consistency will feel. Also interested to see if my SD numbers shrink a bit. 🤷‍♂️
     

    Baron23

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    I'm at the "fine-tuning" point in load development for a couple of my precision rifles, and want to do a neck-tension test with a minimum of supplies (bullets, primers, powder). Looking for the best way to optimize supplies, and still get a good test. I use a Redding FL Type S sizing die with a whole bunch of different internal bushings available, and the 21st Century full expander mandrel set ... so I have the hardware to do any combinations I want to test. My quandary is that testing a bunch of combinations (bushing alone, mandrel alone, bushing/mandrel combo, mandrel first then bushing, bushing first then mandrel, etc.) will take a ton of time and a bunch of supplies. Anybody got a "best practice" method that can get this done in 15-to-20 rounds? BTW ... I'm not "unhappy" with current neck tension and I'm getting smooth bullet seating with acceptable SD's ... but I just want to make sure I can't invest a little time and get even better results. (Note: I wish I had a way other than "feel" to measure seating pressure, but I don't.)

    Left to my own devices, I'd probably "size down" with a relatively compact bushing size, and then do multiple 3-shot group tests "sizing up" with the five different mandrel sizes above and below what I'm currently using to test for both SD and group sizes. Am I on the right track ... or is there a better way to do this using 20-ish rounds?
    Uh, pin gauges? Travers sells individual ones (vice a large set).

    They will tell you wtf the ID is and hence the degree of inference fit.

    I believe the term interference fit more accurate to what I described as I think the actual neck tension (force to move the bullet out of the neck) would include other factors like how clean the neck is…or if it’s too clean and getting sticky, degree of hardness of the brass, and I don’t know what else.

    But I’m def no expert and am willing to be corrected.
     

    Feniks Technologies

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    There’s no free lunch.

    Anytime you attempt to test almost anything and want to “save components” you are now opening yourself up to a very high amount of variance due to dispersion.

    The problem this creates is say you shoot 2 and 3 shot groups. Once you extrapolate the data with correction factors that allow for the probable dispersion in groups size, you end up with several seating depths or neck ID that are all just as likely to perform the same as likely to perform better or worse than one another.

    When looking to save components, you’ll have to accept you’re ok with “good enough” but happy if you get lucky for better performance.

    So, you could do a seating depth and interference fit test with 2 and 3 shot groups and based on that, pick the area that appears to perform the best.

    Then it’s just hoping it holds up. It’s hard to not get a modern rifle to shoot .5 or .7 at the most. So, when saving components, be ok with that and be happy if it’s better.


    Ironically, most people attempting to save components are actually wasting those components they use for testing that’s barely or no better than randomly picking.
     

    Feniks Technologies

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    Sample size conversation aside…..

    Pin gauges will be your friend here. You can buy them individually in .0005” increments for a few dollars apiece.

    Decide what inside neck diameters you want to test and buy those. Then use mandrels to achieve the desired fit on the pin gauge. Depending on spring back and such, it likely won’t be a one for one. IE a .241 mandrel won’t leave the neck at a .241 ID. It will likely be a .240 or .2405 ID.


    For practical type rifles, I find thinks like interference fit and other parts that make up the sum of neck tension…..show up on the chrono more so than paper. If you are jumping bullets that is.

    As the initial pressure build up is being held back by the bullet which is being held by the neck. You want enough tension the bullet doesn’t move from normal handling, and after that, you just need it to be consistent and release the bullet as close to the same time as every round.

    Basically, you don’t want a bullet to dislodge enough milliseconds faster or slower than another bullet that the velocity difference is enough to matter.

    When jamming bullets you’ll want a much smaller/tighter ID. As the bullet will want to push into the case once it’s chambered into the lands. Or at least move in a consistent way bullet to bullet.
     

    NCgreentick

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    I've been thinking about messing with the new Forster neck tension gauge:
    Here
    How do you know if your bushings/mandrels are actually setting such tight tolerances?
    I mean with spring back of the brass and whatever other variables, how do you know they are holding their "settings"?
    Other than like you said, the feel when seating.
    Just an idea floating around in my head.
     

    Feniks Technologies

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    I've been thinking about messing with the new Forster neck tension gauge:
    Here
    How do you know if your bushings/mandrels are actually setting such tight tolerances?
    I mean with spring back of the brass and whatever other variables, how do you know they are holding their "settings"?
    Other than like you said, the feel when seating.
    Just an idea floating around in my head.

    That’s literally just an expensive pin gauge.

    You can get the same thing in individual pin gauges for probably 25% of those pricing. Plus you can choose down to .0005” increments.

    Forster is (and I don’t blame them) capitalizing on the growing popularity of pin gauges.
     

    rustyinbend

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    I'd propose it's goal dependent - which I don't think you laid out. Are you after smallest groups? PRS match loads? ELR matches? Tinkering because it's fun?

    Plan from the objective backwards - you may be there, or you may need a full box of test rounds.
    Goals are (a) small groups, (b) low SD's, and (c) accuracy at long range.
     

    rustyinbend

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    Through my research I believe that the only true way to achieve consistent neck tension when using bushing dies is to first neck turn the brass. I have been loading with a bushing up to now without turning and haven’t had any issues but have noticed somewhat differing seating pressures at times. I just yesterday started to process a batch of brass using a collet/mandrel neck only sizing die, no bushing used at all. Will charge and seat later today and am looking forward to how the seating consistency will feel. Also interested to see if my SD numbers shrink a bit. 🤷‍♂️
    I've got the "stuff" to neck-turm, but it just seems like so much effort for minor payback. Perhaps I should reconsider ...
     

    ma smith

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    Pin gauges will def show any inconsisency in your brass from wall thickness or whatever using bushing dies.

    You can feel when the neck tension is 'just so' vs when its every so slightly off. The goldilocks neck tension seems to hava a spring tension/grip on the pin guague. There as occasionaly you get one that does't have this feeling. The feeling is "too loose" or "too tight".

    This isn't scientific measurement of neck tension as much as it is a test of consistency of the brass after going thru a process. Its true there is ever so slight a variation in the neck walls of even high quality brass like lapua.

    This lends credence to the guys saying if you eliminate that variance thru neck turning, you will get more even neck tension.
     

    ma smith

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    But I have no idea if that is worth the process hassle of actually neck turning all your brass.

    It seems if you have enough room in your chamber (not uber tight neck) you can accomodate some variance. Then the issue becomes is 'testing' and correcting consistency just as much work as neck turning? You still have to touch every piece of brass, which adds over say 100+ unit batches. The actual corrections might only be a much smaller amount and you wouldn't need neck turning tools...but it still sounds like a ton of hassle...
     

    rustyinbend

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    Pin gauges will def show any inconsisency in your brass from wall thickness or whatever using bushing dies.

    You can feel when the neck tension is 'just so' vs when its every so slightly off. The goldilocks neck tension seems to hava a spring tension/grip on the pin guague. There as occasionaly you get one that does't have this feeling. The feeling is "too loose" or "too tight".

    This isn't scientific measurement of neck tension as much as it is a test of consistency of the brass after going thru a process. Its true there is ever so slight a variation in the neck walls of even high quality brass like lapua.

    This lends credence to the guys saying if you eliminate that variance thru neck turning, you will get more even neck tension.
    I'm curious ... If I have a full set of Mandrels from 21st Century that go from very small to very large in .0005 increments ... why do I need Pin Gauges? I mean, at the end of the day, I don't care about "the number", I care about "the result". So regardless of spring-back or actual diameter, if I have sufficient variety in mandrel sizes to adjust-test-repeat and find the size that works ... I shouldn't need Pin Gauges, right?
     

    Buckley

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    I enjoy pulling the trigger much more than playing with brass. Back to the good enough.

    You are searching for an inexpensive way to test your process and I think I have a possible answer. While seating yesterday I did perceive a more consistent amount of force though my non-calibrated feel-o-meter arm after using a collet neck die as opposed to the bushing I had been using previously. I don’t currently have a trigger pull gauge but was thinking one should be able to measure/meter the seating force by gently lowering your press arm until the bullet is resting in the stem and then pull the arm through the rest of the stroke with a trigger gauge and note the force.

    Pin gauges will definitely determine ID but there are still so many variables such as differences in brass thickness, how clean or smooth the inside is, the hardness, etc.

    Yep, I will stay seated on the Good Enough bus and enjoy the ride, already lost too much hair to be splitting what is left.


    Cheers
     

    Baron23

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    I'm curious ... If I have a full set of Mandrels from 21st Century that go from very small to very large in .0005 increments ... why do I need Pin Gauges? I mean, at the end of the day, I don't care about "the number", I care about "the result". So regardless of spring-back or actual diameter, if I have sufficient variety in mandrel sizes to adjust-test-repeat and find the size that works ... I shouldn't need Pin Gauges, right?
    Ah, I thought you asked how to test neck tension w minimum tools and supplies. Hence, the suggestion.
     

    ma smith

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    I'm curious ... If I have a full set of Mandrels from 21st Century that go from very small to very large in .0005 increments ... why do I need Pin Gauges? I mean, at the end of the day, I don't care about "the number", I care about "the result". So regardless of spring-back or actual diameter, if I have sufficient variety in mandrel sizes to adjust-test-repeat and find the size that works ... I shouldn't need Pin Gauges, right?
    No worries, I don't think the suggestion is to duplicate tooling.

    gauge
    /ɡāj/
    an instrument or device for measuring the magnitude, amount, or contents of something, typically with a visual display of such information.
    "a fuel gauge"
    There are dies out there that let you use pin-gauges as mandrels if you want to go that route. Alternatively, you can use mandrels as gauges--assuming sufficiently complete set of mandrels (which are typically 10x more $$ than pins). The bigger point is any tool used when doing a measurement, the item being used is being referred to as a gauge , because thats more accurate.
     
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    rustyinbend

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    I enjoy pulling the trigger much more than playing with brass. Back to the good enough.

    You are searching for an inexpensive way to test your process and I think I have a possible answer. While seating yesterday I did perceive a more consistent amount of force though my non-calibrated feel-o-meter arm after using a collet neck die as opposed to the bushing I had been using previously. I don’t currently have a trigger pull gauge but was thinking one should be able to measure/meter the seating force by gently lowering your press arm until the bullet is resting in the stem and then pull the arm through the rest of the stroke with a trigger gauge and note the force.

    Pin gauges will definitely determine ID but there are still so many variables such as differences in brass thickness, how clean or smooth the inside is, the hardness, etc.

    Yep, I will stay seated on the Good Enough bus and enjoy the ride, already lost too much hair to be splitting what is left.


    Cheers
    A trigger gauge ... what a great idea !!! I've got one of those. I'm gonna give that a try and see if it works better than the "Feel-O-Meter".
     

    6.5SH

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    I'm surprised there isn't an arduino version of this out:

    The pressure sensor itself is less than $25

    The RSI one was discontinued around 2001. The AMP press certainly took things much further. I wouldn't call either one affordable though.
     

    rustyinbend

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    Yeah, saw that one ... discontinued two decades ago. The AMP press is amazing, but I'm just not ready to toss that much money into it when I already have all the seating dies and other tools that get me "close" to perfect. Somebody should make an "Electric Shell-Holder" that is pressure-sensitive and sells for $20. (Hey, stop laughing, it could happen.)
     

    Feniks Technologies

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    I'm curious ... If I have a full set of Mandrels from 21st Century that go from very small to very large in .0005 increments ... why do I need Pin Gauges? I mean, at the end of the day, I don't care about "the number", I care about "the result". So regardless of spring-back or actual diameter, if I have sufficient variety in mandrel sizes to adjust-test-repeat and find the size that works ... I shouldn't need Pin Gauges, right?

    If you find your brass is consistent enough each firing, yes.

    You could also use your mandrel set as pin gauges. Basically the same thing.


    Just be aware that depending on your brass and your process, the mandrel may vary slightly that gets the same neck ID. IE, for X amount of firings, to get .241 ID, you need a .2415 mandrel. And then you find this next firing, for whatever reason, it takes a .242 mandrel to keep that same .241

    But, as I said, if you have a complete set of mandrels in .0005 increments, you basically already have pin gauges.

    There’s also friction and other such things like carbon buildup that may or may not affect the ID at different firings.
     
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    bax

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    That is good to know, thanks. Link to a decent set?
    You only need 3 or 4 pin gauges for each caliber. For example, assume you are sizing for 308. You don't need a 308 gauge, you have bullets that are 308. You probably don't need a 307, you should be able to use your fingers to push a bullet into that diameter. You probably want a 306, 305 and 304. 303 is .005 and that is pretty tight. If you want to get fancy, you could buy the half-thou steps.

    I have pin gauges for 30, 22, and large and small for primer pockets. YMMV.
     

    6.5SH

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    Yeah, saw that one ... discontinued two decades ago. The AMP press is amazing, but I'm just not ready to toss that much money into it when I already have all the seating dies and other tools that get me "close" to perfect. Somebody should make an "Electric Shell-Holder" that is pressure-sensitive and sells for $20. (Hey, stop laughing, it could happen.)
    Using the Ammolytics rifle accelerometer project as a baseline, are looking at ~$100 in parts excluding the shell holder that would hold the pressure sensor is my guesstimate.
     

    acudaowner

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    personally Id set the next bullet I want to use with the case on top if it stays up there it's good just need to use the expanding mandrels , if it falls inside the case I need to resize make it tight again .