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Old August 7, 2022, 10:54 PM   #1
akinswi
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Neck Tension and seating depth

Is there any correlation between neck tension and seating depth? In other words if I decide to increase neck tension by 1 thousandths would I need to adjust my seating depth.

Thanks
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Old August 8, 2022, 05:29 AM   #2
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I would say most likely. With increased neck tension it could hold onto the bullet a little longer changing the timing in the harmonics. Meaning you may need to re-tune the seating depth.
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Old August 8, 2022, 06:03 AM   #3
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No. It won't change seating depth.
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Old August 8, 2022, 06:38 AM   #4
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I say you should continue to seat your bullets at the same die setting you have been using, and see if there is any difference in the COL measurement. I would be suspicious that the increased tension would cause an increase in resistance to seating, producing a slightly longer bullet, and changing the distance to the lands.
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Old August 8, 2022, 03:15 PM   #5
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Don't you mean increasing the interference fit of bullet to case neck wherein the case neck inside diameter is made smaller?

Last edited by Bart B.; August 8, 2022 at 03:20 PM.
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Old August 8, 2022, 03:27 PM   #6
akinswi
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Quote:
Originally Posted by Bart B. View Post
Don't you mean increasing the interference fit of bullet to case neck wherein the case neck inside diameter is made smaller?
isnt that called neck tension?
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Old August 8, 2022, 03:43 PM   #7
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Quote:
I would be suspicious that the increased tension would cause an increase in resistance to seating, producing a slightly longer bullet, and changing the distance to the lands.
I don't see where that would matter. Seating depth depends on "fixed" constants that you set, and consistency of the bullets contacting the seating stem at the same point of their length.

Squeezing the neck a little tighter means the force needed to seat the bullet will increase slightly, but that doesn't change the distance of full ram travel, though if it increases enough to where the seating stem is actually digging into the bullet, you've gone too far.
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Old August 8, 2022, 03:55 PM   #8
Bart B.
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Originally Posted by akinswi View Post
isnt that called neck tension?
Often it is, but the correct term is from SAAMI's glossary...

BULLET PULL
The force required to extract a bullet from the case into which it was loaded.

Military ammo has specs for it. 60 or more pounds for 30 caliber service ammo, at least 20 pounds for match ammo. For each pound of force needed for these,13 psi in the case is required. Bullet cross section area is about 1/13th square inch.

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Old August 8, 2022, 05:09 PM   #9
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I prefer the way Quickload refers to it as start pressure--makes more sense in terms of intuitively indicating an additive relationship to the pressure rating of the charge.
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Old August 8, 2022, 05:40 PM   #10
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Quote:
Originally Posted by sako2 View Post
No. It won't change seating depth.
This is the simple answer .
Typically seating depth and neck tension are independant .
Some folks like to complicate things ... but it realy isn't necessary .

Remember ... D.O.I. ... (Don't Overthink It)

Overthink is the correct way to spell it ... trust me !
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Old August 8, 2022, 07:16 PM   #11
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Quote:
Originally Posted by Bart B. View Post
Often it is, but the correct term is from SAAMI's glossary...

BULLET PULL
The force required to extract a bullet from the case into which it was loaded.

Military ammo has specs for it. 60 or more pounds for 30 caliber service ammo, at least 20 pounds for match ammo. For each pound of force needed for these,13 psi in the case is required. Bullet cross section area is about 1/13th square inch.
60lbs vs 20lbs is quite a difference, Im assuming it has to do more with service ammunition is crimped into place, vs match ammo is not.
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Old August 8, 2022, 11:25 PM   #12
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44AMP, do you really get each and every cartridge exactly the same COL, as measured by a collimator attached to a caliper, (not OAL from cartridge case base to bullet tip) with each stroke of your press?

MAYBE if you use the same manufacturer's new brass, but my experience has been, reloading multiple brass firings, particularly from multiple manufacturers, usually results in perhaps minute changes in the final OAL, which might be traceable to changes in resized neck/mouth thickness, which offers resistance to seating that can be perceived if one is paying attention at that point in the process. One variable might be the insufficient depth of primer insertion, elongating the OAL, while another can be a subtle difference in the position of the ogive on each bullet in a group of the same lot, depending on the quality of manufacturer or intent of use as target, hunting or match.
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Old August 9, 2022, 11:22 AM   #13
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Quote:
44AMP, do you really get each and every cartridge exactly the same COL, as measured by a collimator attached to a caliper, (not OAL from cartridge case base to bullet tip) with each stroke of your press?
No, and I'm not trying to. and, just out of curiosity, where the hell did that come from?? The only collimator I own is a cheapie intended for scope boresighting and I haven't used it in years. And I do measure CARTRIDGE OVER ALL LENGTH from case base to bullet tip. How do YOU measure it??

My calipers measure in thousandths, and one can "eyeball" half way between marks, which means a +/- of a bit less than 0.0005" and that's more than adequate for me, since I'm only concerned with measuring to the nearest 0.001" anyway.

For me, tiny variations in over all length, (due to tiny variations in actual bullet tip length) are essentially irrelevant.
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Old August 9, 2022, 11:31 PM   #14
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44AMP, it seems like I hit a nerve somehow or you're having a bad day, so I won't bother to clarify or continue on this thread.
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Old August 10, 2022, 04:11 PM   #15
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Quote:
Originally Posted by cdoc42 View Post
44AMP, do you really get each and every cartridge exactly the same COL, as measured by a collimator attached to a caliper, (not OAL from cartridge case base to bullet tip) with each stroke of your press?.
I've never heard of such a thing. All the collimators I've seen are used to measure optical things.

https://www.google.com/search?q=coll...obile&ie=UTF-8
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Old August 10, 2022, 07:49 PM   #16
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I’m interpreting the question like this. If increasing neck tension should I seat a bullet out further. I.E. having less of a bullets bearing surface seated in the neck to compensate for the increased hold on the bullet, thus allowing it to release with the same pressure but allowing you the option of seating a bullet out further to either chase the lands or increase powder capacity. Not sure if this makes sense, but just my interpretation of the OP’s original question.
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Old August 10, 2022, 09:42 PM   #17
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I'm still wondering just how he measures cartridge over all length if not from the case base to the bullet tip.

I mean, how else would one do it??

As to seating the bullet out a little more, to make up for the change in bullet pull, I guess you could, but it would require quite a bit of calculation.

And I have no clue how to determine some of the factors you'd need to know, but my guess would be that, first, you'd need to know the force needed for what you currently load, then figure out some way to include the surface area in that force.

Then you'd have to do the same for what the force of the increased pull is, over the same area, and then adjust the area of bullet & case contact to return the force/area amount to what it was in your original load.

Which I guess is do-able if you know how, but I have to wonder, WHY?? I mean, why bother??

And, particularly why not shoot the ammo with the "adjusted" neck tension and see what it does, before making any other changes?
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Old August 11, 2022, 10:21 AM   #18
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44amp,

I typically measure from base to ogive. I rarely measure from overall length from base to tip of the bullet since my 168SMKs are not pointed and they vary quite a bit . But the ogives which I sort by in 1 thousandths increments are usually spot on.

When I seat them almost all my loaded ammo from base to ogive come within 1 thousandths of eachother, which with the handheld instruments I have is the best that I can do.

The reason for my question is that since the cartridge Im loading for 30-06 isnt loaded to max , was wondering if more neck tension would lower my SD/ES since its holding onto the bullet for longer period time and inturn provide better ignition thus lowering my SD/ES

Last edited by akinswi; August 11, 2022 at 01:12 PM.
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Old August 11, 2022, 03:22 PM   #19
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Loading using base to a point on the ogive that you choose, works for your specific situation ,means nothing to any other situation. And its not the standard definition for measuring cartridge over all length.

Works for you and give you uniform results, its not wrong.

I think the thing you should do is load and shoot a test batch with no change but the increased neck tension and see what the actual results are.

Theory says lots of things but real world performance is what matters.

Sometimes, little changes don't show measurable differences. Sometimes they do. and sometimes the change actually affect performance in some way.

ONLY testing in your gun with your ammo will tell you what does, and doesn't happen.

Quote:
was wondering if more neck tension would lower my SD/ES since its holding onto the bullet for longer period time and inturn provide better ignition thus lowering my SD/ES
That's what theory says, but the real world results may not be a linear change. And small changes might not create a measurable result amongst all the other factors involved.

I'm sure you've noticed performance "plateaus" in handloading, where making a small change doesn't seem to have any result, and certain points where it does. These are the same in principle, but the exact point (and amount) of the change is specific to your gun and your ammo combination.

Load and shoot some with the (slightly) increased neck tension. If there's no (safety) issues shoot enough for a reasonable size sample, and see if you need to do something more, or if you just want to,...

Nothing wrong with just wanting to, if you're seeking something, you have to look to find it (experiment, test shooting etc) until you either find it, or find you're not going to get it.

Good Luck!
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Old August 12, 2022, 11:04 AM   #20
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The SAAMI glossary is available to check a term's definition. I think we would be safely within Fair Use Doctrine limitations to put up a few lines here:

Quote:
Originally Posted by SAAMI

OVERALL LENGTH

1. Firearm: The dimension measured parallel to the axis of the bore from the muzzle to a line at right angles to the axis and tangent to the rearmost point of the butt-plate or grip.

2. Ammunition: The greatest dimension of a loaded cartridge, i.e., from face of the head to the tip of the bullet for centerfire or rimfire or to the crimp for shotshells or blanks (not to be confused with the uncrimped length in a shotshell.)
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Old August 12, 2022, 04:14 PM   #21
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Remember ... D.O.I. ... (Don't Overthink It)
In most things I've experienced in my 73 years, I try not to trivialize the momentus or complicate the obvious. The last couple of years has me measuring the leade in my rifles with the Hornady OAL tool. The only time I worry about neck tension is loading Cast bullets in 357, 41, 44, or 45 Colt. Heavy bullet pulls have helped me produce accurate loads over the years.
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Old August 12, 2022, 10:48 PM   #22
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I’m returning to this conversation at this point because it is clear now that OP was talking about seating depth and COAL measurements in a rifle, not a handgun, which is what I had initially interpreted and addressed.

Since handloaders and particularly bench-rest shooters measure seating from the base of the case to the undefined and ever-changing point on bullets generally accepted and called the ogive, the discussion of measuring from the base to the tip of the bullet is rather incongruous to the question poised.

It would be useful if some staffers educate rather than obfuscate and become argumentative as a result in order to demonstrate the superiority of experience and knowledge. Sharing information is more important than proving you know more than anyone else.

44AMP suggested, in post #19 the following: “I think the thing you should do is load and shoot a test batch with no change but the increased neck tension and see what the actual results are”

Compare that to my post #4: “I say you should continue to seat your bullets at the same die setting you have been using, and see if there is any difference in the COL measurement.”

44, does this answer your question in post #17?: “I'm still wondering just how he measures cartridge over all length if not from the case base to the bullet tip.”

I’m not interested in having a war of words, but I think portions of this discussion needed clarification.
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Old August 13, 2022, 01:24 AM   #23
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Quote:
44, does this answer your question in post #17?: “I'm still wondering just how he measures cartridge over all length if not from the case base to the bullet tip.”
Yes, thank you, it does answer my question. You are not measuring the entire length of the loaded round.

Quote:
Since handloaders and particularly bench-rest shooters measure seating from the base of the case to the undefined and ever-changing point on bullets generally accepted and called the ogive, the discussion of measuring from the base to the tip of the bullet is rather incongruous to the question poised.
I don't think discussion to understand how we are using terms, when there appears to be a difference between how people understand them is incongruous , I think its a valid point.

We have had definitions essentially standardized for generations, listed in the reloading glossaries and standard references including SAAMI. Look at Uncle Nick's excellent drawing and the identification of the various parts of the round and bullet.

Look what part of the bullet is defined as the ogive. It's not a single point, it is the entire curved/sloped portion of the bullet.

Uncle Nick also gives us the SAAMI definition of Cartridge OverAll Length, and they measure it from the case base to the bullet tip.

In a context such as reloading, where precise communication and uniform understanding of terminology is needed we need to be on the "same page" or misunderstandings can result.

If I call something a widgit and others call it a dingus, none of us is sure what the other is talking about, even if we think we are.

Using terminology in a non-standard manner, without sufficient context or explanation is not a good way to discuss technical matters.
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Old August 13, 2022, 08:46 AM   #24
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"If I call something a widgit and others call it a dingus, none of us is sure what the other is talking about, even if we think we are."

You are correct in an academic sense. But I'd be willing to bet that your repeated insistence that everyone should regard the ogive as nothing more than "the entire curved/sloped portion of the bullet" is disregarded by the majority of participants on these forums. Even though that is true, it lends nothing to the practical application of bullet seating. I've not seen any posts where the participant says anything other than "I measure cartridge base to the ogive." We all know what he means and it is not necessary to point out to the neophytes on these forums that is more correct to say "I measure from the cartridge base to a specific point on the ogive."

With regard to Unclenick's presentation, I noticed, and agree, that the SAAMI definition of COAL is from the base to the tip of the bullet. But, disregarding the potential deformation of the lead tip alters the precise measurement, how does that COAL address the jump to the lands by disregarding the ogive?
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Old August 13, 2022, 09:51 AM   #25
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Quote:
Originally Posted by cdoc42 View Post
"If I call something a widgit and others call it a dingus, none of us is sure what the other is talking about, even if we think we are."

You are correct in an academic sense. But I'd be willing to bet that your repeated insistence that everyone should regard the ogive as nothing more than "the entire curved/sloped portion of the bullet" is disregarded by the majority of participants on these forums. Even though that is true, it lends nothing to the practical application of bullet seating. I've not seen any posts where the participant says anything other than "I measure cartridge base to the ogive." We all know what he means and it is not necessary to point out to the neophytes on these forums that is more correct to say "I measure from the cartridge base to a specific point on the ogive."

With regard to Unclenick's presentation, I noticed, and agree, that the SAAMI definition of COAL is from the base to the tip of the bullet. But, disregarding the potential deformation of the lead tip alters the precise measurement, how does that COAL address the jump to the lands by disregarding the ogive?

Its my understanding that it doesn’t. My understanding the tip of the bullet has more to do with BC and nothing with barrel harmonics.

This is the reason why I stop using the overall measurement of the cartridge and try to measure from the base to the ogive so I know all my jumps to the lands are consistent as I can measure with calipers and a bullet comparator.

For my particular application an M1 Garand, as long as the overall length is under 3.340 it will fit the enbloc clip and feed correctly.

But with my base to ogive measurement at 2.717 the actual overall length from base to tip of the bullet will vary from 3.318 to 3.322 this is because the tips are jagged and not all the same length.

But 44amp is correct if i reduce my neck tension down , Will need too see what results are on paper.

But I did do a test where I sorted 100 bullets by Overall length “Base to Tips”,
Then by base to ogive. And sorted by the latter gave me the best results

Last edited by akinswi; August 13, 2022 at 10:25 AM.
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