View Full Version : Nonsensical Headspace Measurements on 223rem cases...??
How would full-length sizing a case increase the headspace measurement on a .223 case, and charging/seating/crimping decrease the headspace measurement??
This weekend, I started taking headspace measurements on some 223 cases in my stockpile in various states on the way to being reloaded, in hopes of starting the process of setting up my new Dillon 650 for reloading 223. I measured unprepped and prepped cases, as well as fully loaded rounds (definitions included below). All of the work done on the cases was performed on a Lee Turret press.
The observations which do not make sense to me, are that:
1) the fully loaded rounds have a shorter headspace (length from case head to the "datum" on the cartridge's shoulder, 0.330" diameter) than the prepped cases (cases which have been sized and primed ONLY), and
2) the prepped cases have - on average - a longer headspace than that of the unprepped cases.
What is going on??
Data is for headspace dimensions measured for 223 cases in various states in the reloading process.
https://i.imgur.com/Ol24UUU.jpg
"Unprepped": picked up of the range, most likely once-fired through my rifle.
Mean = 1.463603"
Median = 1.464"
Std. Dev. = 0.001701"
N = 34
"Prepped": full-length sized, primed, and trimmed to proper case length.
Mean = 1.465595"
Median = 1.468"
Std. Dev. = 0.004535"
N = 21
"Loaded": prepped cases that have been charged with powder, bullet seated, and crimped. In other words, fully loaded rounds, ready to fire.
Mean = 1.456017"
Median = 1.4555"
Std. Dev. = 0.003062"
N = 30
There are uneven numbers of cases in each category because I just grabbed a random number of prepped and unprepped cases from my reloading bins, and there are 30 rounds in the loaded column because I went through and measured what I already had loaded in a magazine.
The uniform dimensions of the unprepped cases I take to be due to the fact that most of them came from my rifle (i.e., they have been expanded to somewhat uniform dimensions by the rifle's chamber itself). Now, some of the cases I picked up at the range were not fired from my rifle, so the outliers in the unprepped case category could be due to that, or at least some of them could be due to that.
Unprepped
1.464
1.464
1.464
1.464
1.4635
1.464
1.465
1.466
1.464
1.461
1.465
1.464
1.462
1.463
1.459
1.4635
1.465
1.464
1.464
1.465
1.46
1.464
1.463
1.46
1.46
1.464
1.464
1.465
1.4645
1.464
1.465
1.465
1.464
1.466
Prepped
1.466
1.4685
1.468
1.466
1.468
1.47
1.466
1.461
1.468
1.455
1.468
1.468
1.467
1.465
1.468
1.469
1.457
1.468
1.459
1.459
1.473
Loaded
1.452
1.458
1.452
1.453
1.4535
1.459
1.462
1.459
1.452
1.456
1.461
1.46
1.456
1.454
1.46
1.455
1.453
1.458
1.452
1.458
1.452
1.454
1.459
1.46
1.455
1.457
1.454
1.453
1.455
1.458
Under the wrong conditions, full length sizing can make headspace longer. And firing can make the headspace shrink. This is a sign that you are not bumping the shoulder back enough.
I have no good explanation as to how headspace is changing during seating/charging.
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Thanks, P. I'm going to make it out to the range this week, and I will obtain some freshly-fired brass and measure that too.
I may even proceed to resize some of it, just to see what a given piece of brass does on the way through my process, to confirm that the observations posted above are indeed consistent.
Expander balls ripping out of your case on the upstroke might be the problem. I run a die without the expander ball, and use a neck expander die which sizes on the down stroke.
If you must run the expander, lubing the inside of the necks will help reduce the havoc those things do to your brass.
And.. get a chamber gauge. Good God that's a lot of wasted time measuring head space. :suicide2:
Thanks, Mark.
How much faster is a case gauge versus putting the case between two jaws of a mic with a Hornady headspace gauge clamped on?
Could FL size/decap without the expander ball, then try one of those neck sizers. Any downside to this approach? Is neck lube still required?
And.. get a chamber gauge. Good God that's a lot of wasted time measuring head space. :suicide2:
Ah, you're saying for this particular set if observations. Gotcha.
And.. get a chamber gauge. Good God that's a lot of wasted time measuring head space. :suicide2:
Thanks, Mark.
How much faster is a case gauge versus putting the case between two jaws of a mic with a Hornady headspace gauge clamped on?
Could FL size/decap without the expander ball, then try one of those neck sizers. Any downside to this approach? Is neck lube still required?
I don't use neck lube. The only downside is you have two steps instead of one. Depending on how good you want the ammo to be, it may be worth it. Also... the upside to the neck expander die is that you have almost no case trimming to deal with on reloaded brass because the case stretch is eliminated.
Once fired XM193 brass for example will still require massive trimming. But subsequent loads will require very little trimming.
I don't use neck lube. The only downside is you have two steps instead of one. Depending on how good you want the ammo to be, it may be worth it. Also... the upside to the neck expander die is that you have almost no case trimming to deal with on reloaded brass because the case stretch is eliminated.
Once fired XM193 brass for example will still require massive trimming. But subsequent loads will require very little trimming.
Mark, what neck sizing die do you use?
No problem on a progressive, to have two steps versus one, that is. May try that.
Thanks, man.
I'm also going to track the headspace of a case all the way through the reloading process.
I don't use neck lube. The only downside is you have two steps instead of one. Depending on how good you want the ammo to be, it may be worth it. Also... the upside to the neck expander die is that you have almost no case trimming to deal with on reloaded brass because the case stretch is eliminated.
Once fired XM193 brass for example will still require massive trimming. But subsequent loads will require very little trimming.
Good call on the expander ball as a cause. I like that theory. What I mentioned only can only happen by a 1-2 thousanth or so until you can't even chamber the round.
Lots of us don't use an expander ball. I use a Forster full length resizing die with the expander removed. Then run a Lyman M die with some imperial dry neck lube but not all the way to the step. This opens the neck by 1 thousanth.
Another issue with your prepped cases is there is way too much variance in headspace. I measure headspace like you with the Hornady tool and calipers. My brass is very consistent, with headspace variations of 1 thousanth or less.
Try a test, grab 10 unprepped cases. Remove your expander ball and size them then measure them and see if they are consistent...if they are consistent you know the expander ball is causing problems.
Another thing to check is measure the same case 5 times. Do you get the same measurement? If not that is a problem.
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With Dillons the powder die flairs the neck for placing the bullet, so I'm wondering if you need the expander ball at all after it's been sized once.
Don't know why I have thought of this before, since I've had some issues with loose neck tension on some calibers.
Mark, what neck sizing die do you use?
I think it's just an RCBS .223 neck expander die. Every time I've forgotten the exact die, the subject comes back up. :p
With Dillons the powder die flairs the neck for placing the bullet, so I'm wondering if you need the expander ball at all after it's been sized once.
Don't know why I have thought of this before, since I've had some issues with loose neck tension on some calibers.
My Dillon flares on pistol only. On .223, I was getting jacket shavings without the expander die.
Good call on the expander ball as a cause. I like that theory.
Most all in one sizing dies work by squeezing the neck down to an undersized shape... then they rip the ball back out to open it back up on the upstroke. This causes stretch, runout, excessive working of the neck, etc. It's all bad.
I don't think I'd use an expander ball even if all my ammo was fmj blaster.
My Dillon flares on pistol only. On .223, I was getting jacket shavings without the expander die.
I knew there was a reason!
Most all in one sizing dies work by squeezing the neck down to an undersized shape... then they rip the ball back out to open it back up on the upstroke. This causes stretch, runout, excessive working of the neck, etc. It's all bad.
I don't think I'd use an expander ball even if all my ammo was fmj blaster.Yup I can confirm the expander ball hurts concentricity. I went all OCD with an accuracy one concentricity gauge, and resizing without the ball, then with the Lyman M was better.
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I went all OCD with an accuracy one concentricity gauge
Same here. I try not to live by every measurement possible... but the expander ball was worth the time to study.
Thanks guys. I will try to take some measurements as soon as possible, using my old Lee turret that I still have set up for this.
Side bar question: I use a Hornady FL sizing die and Lee seater an me crimp dies; anyone know if these are problematic in a Dillon progressive?
If you polish the expander and lube the inside of the case neck your expander will do no harm.
Below a close up photo of a new RCBS expander, polish it smooth or buy a carbide expander.
https://i.imgur.com/5Rqdvuh.jpg
A case "grows" when full length resized and squeezes the case shoulder upward.
https://i.imgur.com/wm05ArY.gif
And variations in shoulder location are caused by brass spring back after firing and sizing due to brass hardness and annealing.
If you want more uniform shoulder locations then pause for 3 to 4 seconds at the top of the ram stroke. This pausing reduces brass spring back and more case uniformity.
I use a home made case lube of lanolin and alcohol and spray the cases inside a large zip lock bag. I then close the zip lock bag and squeeze and spread the lube and this puts enough lube inside the case neck.
Don't be a Ewok and not lube your case necks. :nono:
https://i.imgur.com/W8kkVio.jpg
Okay. Will confirm that shell plate is making contact with the die. I would think - correct me if I'm wrong - that necessitates that the shoulder is indeed being pushed back, i.e., being set back the max possible amount.
If it is indeed pushing the shoulder back and being sized the max amount possible, then it would be most likely that the expander ball is increasing the headspace dimensions by stretching the neck on the way out, correct?
I'm using a Lee FCD for the crimping step, which I didn't even think touched the shoulder. So, is it more likely that the loaded rounds have shorter headspace due to being pushed back during the bullet seating step?
Chambers and resizing dies vary in sized and your die is adjustable up and down for the correct amount of shoulder bump.
Example I have a standard Lee full length .223 die that reduces the case diameter more than my RCBS small base die. And this same lee die will push the shoulder back .009 more than my .223 GO gauge if it contacts the shell holder.
I do not have a progressive press so I assume when you say "shell plate" you have a progressive press. But it is my understanding a progressive press can cause more variations in shoulder location. Meaning if the case does not make hard contact with the shell holder it will not remove any flex in the press and variations in shoulder location.
I use Redding competition shell holders to control shoulder bump on my Rockchucker press to eliminate flex in the press.
Bottom line, press flex and using mixed brass will cause variations in shoulder location. So again, adjust the die for proper shoulder bump and try pausing at the top of the ram stroke. And remember if the die is adjusted too low and you bump the shoulder back too far this can cause shorter case life and case head separations.
Below a "FIRED" Lake City case from my AR15 and my sizing die is adjusted to push the shoulder back .003 from this measurement. For a semi-auto the thumb rule for shoulder setback is .003 to .006 and if needed you can average the amount of shoulder bump between these two points.
https://i.imgur.com/H0SXHH8.jpg
Thanks for the info.
Gotcha on the shortening too much thing; definitely want to not be overworking my brass if I can help it.
Correction: I've not loaded any on a progressive as of yet, but was only looking at measurements to begin with since I was about to start setting up my Dillon for reloading 223. Everything this far has been loaded on a Lee turret, and for confirming measurements in the course of investigating the conundrum I initially posted about, I will continue using the Lee press.
You're correct - I did use the wrong terminology. I should have said "shell holder" instead of shell plate.
Chambers and resizing dies vary in sized and your die is adjustable up and down for the correct amount of shoulder bump.
Example I have a standard Lee full length .223 die that reduces the case diameter more than my RCBS small base die. And this same lee die will push the shoulder back .009 more than my .223 GO gauge if it contacts the shell holder.
I do not have a progressive press so I assume when you say "shell plate" you have a progressive press. But it is my understanding a progressive press can cause more variations in shoulder location. Meaning if the case does not make hard contact with the shell holder it will not remove any flex in the press and variations in shoulder location.
I use Redding competition shell holders to control shoulder bump on my Rockchucker press to eliminate flex in the press.
Bottom line, press flex and using mixed brass will cause variations in shoulder location. So again, adjust the die for proper shoulder bump and try pausing at the top of the ram stroke. And remember if the die is adjusted too low and you bump the shoulder back too far this can cause shorter case life and case head separations.
Just remember if you are using range pickup brass or buying once fired brass the case headspace measurements "WILL" vary.
Also different brands of new brass will vary in headspace length due to brass spring back after firing. Just like the case will spring back larger after sizing, this is why pausing at the top of the ram stroke helps. This lets the case know who is the boss and stay put after sizing, meaning far less brass spring back.;)
Gotcha on the shortening too much thing; definitely want to not be overworking my brass if I can help it.
Again... CASE GUAGE. It has a min/max. It's a no brainer. Factory ammo usually seats at the min. I set my die to size to average in the middle of the min/max. Over max and you'll get troubles going into battery.
The vast majority of what I have in my unprepped bin had most recently been fired in my rifle. There are, however, some occasional pickups that aren't from me.
Just remember if you are using range pickup brass or buying once fired brass the case headspace measurements "WILL" vary.
Also different brands of new brass will vary in headspace length due to brass spring back after firing. Just like the case will spring back larger after sizing, this is why pausing at the top of the ram stroke helps. This lets the case know who is the boss and stay put after sizing, meaning far less brass spring back.;)
There are, however, some occasional pickups that aren't from me.
Range pick ups don't matter. It's all going through your sizing die anyway. Pappabear and I have scooped up many thousands of rounds of range brass. Every so often you can get a case separation, but that's an inconvenience, not a safety concern. I think I've had 5 in my entire .223 loading career.
I do toss out brass that requires an out of the ordinary amount of effort to resize.... assuming it's been fired out of an out of spec chamber/excessive head spaced gun.
Range pick ups don't matter. It's all going through your sizing die anyway. Pappabear and I have scooped up many thousands of rounds of range brass. Every so often you can get a case separation, but that's an inconvenience, not a safety concern. I think I've had 5 in my entire .223 loading career.
I do toss out brass that requires an out of the ordinary amount of effort to resize.... assuming it's been fired out of an out of spec chamber/excessive head spaced gun.
If I remember correctly markm you are using Dillon dies that are small base dies. Meaning with a standard die brass springback and brass fired in another chamber can matter. Normally a small base die will push the shoulder back .003 more than a standard die.
So, here is some additional data, which indicates that my initial measurements prompting this thread might have been erroneous in some way (maybe not zeroing out the mic, etc., etc.,?). I took twenty cases from totally unprepped through the reloading process, sans powder and primer. The purpose was to be able to see how individual cases were effected by each step in the process.
The same process as I normally employ for reloading was used, and I did not ensure the inside of the necks were lubricated (simply due to the fact that I wanted an apples-to-apples comparison with the cases I originally measured for this thread).
I will dump the raw numbers (screenshot form), and two box plots, showing length and headspace after each reloading step (where applicable - e.g., did/can not measure case length after a bullet has been seated).
In my opinion, nothing looks out-of-place here. Cases lengthen after sizing then the longer cases are indeed being trimmed while the shorter ones aren't touched by the trimmer - this is readily observed by the box plot, where it appears that simply the top of one box has been lopped off, leaving the bottom untouched. Also, unprepped cases starting with longer headspace get bumped by the sizing die, while shorter headspace cases do not, and none are being bumped back an undue amount, it seems (0.002" on average).
- Average case length comes out to 1.750", as desired.
- Average headspace is 1.462".
- Average case length growth from the sizing die is ~10/1000".
- As mentioned before, average shoulder setback is 2/1000".
There are still some high outliers in the headspace category, which could be explained by the spring back phenomenon, possibly.
Of note is that the one case that started with shorter headspace than where the sizing die was bumping all the shoulders back to - case 18, 1.461" unprepped headspace measurement - this case's headspace actually became longer in the sizing die, as expected because of the brass growing while being inserted in the die, but the shoulder never being setback by the die. Is this a concern? I.e., could this cause the head of the case to become unduly weakened due to the brass never being 'crunched' back down at the end of the stroke?
Does anything look strange, unexpected, concerning about any of this?
Also, thank you, everyone, for all of the input into this thread. I appreciate it.
https://i.imgur.com/gdbMdW3.jpg
https://i.imgur.com/2WCBeJ0.jpg
You are a glutten for punishment huh? :p
My sizing die set up is simply turning the die down until a 5 case average squeeze is in near the low shelf on the case gauge. Even with good case lube, not every piece springs back the same. So if 5 pieces look pretty good, I'm done.
I got access to the equipment and tools I got access to. Just wanted to get it done. However, case gauge wouldn't give me actual numbers, right?
I'm not going to measure again though in the future other than to set the dies up initially. Kinds of a one time thing while investigating those inconsistent numbers reported in the first post.
Also, am I using the wrong terminology to refer to the case's head-to-shoulder-datum measurement? Or is it in fact called "case headspace"? Someone is sharpshooting me on another forum where I've posted this, with regards to my terminology (without suggesting the correct terminology), but I've looked up the terms for various case dimensions and "headspace" seems to be correct.
However, case gauge wouldn't give me actual numbers, right?
Who needs actual numbers? I've literally NEVER calculated a shoulder bump. I use the case gauge for all 223 since it's mostly autoloader ammo that needs to be sized to SAAMI. And I use the actual chambers on .308 and 300 WM bolt gun ammo.
Having a nominal bump is worthless info to me other than for pretentious coffee shop conversation. ;)
What is the range on the headspace measurement? I'm having trouble finding this information anywhere.
Edit: meaning, the in-spec range. SAAMI or whatever.
It’s a ‘relative headspace’ measure, when using that Stoney Point or Hornady tool. Measuring once-fired brass
from your gun relative to the die setup measurement. Listen to MarkM, he knows what he speaks!
FWIW I use the RCBS ‘X’ dies to limit case neck growth on semi-autos. Larry Gibson (Cast Boolits) got up to 18 reloads per case out of 308s shot out of an M1A (notoriously hard on brass) ... before he gave up, whereas he only got a few reloads before, regardless of how his sizing dies were adjusted.
Why is it "relative"? The SAAMI diagram I found defines the headspace as the length between the shoulder datum (0.330" diameter) and the case head. The collar of the Hornady tool bottoms out exactly on the 0.330" datum point, and you zero your mic at the same point. So, the resultant dimension being mic'd with the Hornady tool is exactly the same dimension as specified in the SAAMI drawing, namely, shoulder datum to case head.
Right?
What is the range on the headspace measurement? I'm having trouble finding this information anywhere.
Edit: meaning, the in-spec range. SAAMI or whatever.
There's a min/max on the case gauge. Not sure what the range is, but I'd guess +/- .003-.005"
The case guage is brilliant and honest. Years ago I ran a handfull of rounds that weren't bumped back quite enough to spec correctly in the gauge, and they gave me problems going into battery. A pain in the butt lesson to obey the gauge.
Gotcha. Thanks, man.
I think I understand the case gauge now, and why it isn't giving true headspace, but rather just a measurement of the effect of the sizing die on the case.
I'm setting shoulders back 3/1000" on average, so I think this is acceptable for the purposes of this ammo.
If the cartridge headspace varies as much for my ammo as it does, and I drop it in a gauge, it is going to be all over the place. I've read that those gauges have like a 0.003" range between the short and long cartridge headspace lengths....true??
Why is it "relative"? The SAAMI diagram I found defines the headspace as the length between the shoulder datum (0.330" diameter) and the case head. The collar of the Hornady tool bottoms out exactly on the 0.330" datum point, and you zero your mic at the same point. So, the resultant dimension being mic'd with the Hornady tool is exactly the same dimension as specified in the SAAMI drawing, namely, shoulder datum to case head.
Right?This should be the case but it isn't. The Hornady tool can be used as a comparator only. Meaning you can measure to compare one case to another, or measure a case to compare it to a headspace gauge.
If you measure headspace gauges you will find that there is a big discrepancy, they don't measure what they are. I think the Hornady tool has a chamfer that makes it not measure the true datum line.
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If the cartridge headspace varies as much for my ammo as it does, and I drop it in a gauge, it is going to be all over the place. I've read that those gauges have like a 0.003" range between the short and long cartridge headspace lengths....true??
.003" sounds about right. I don't have mine in front of me.
fedupflyer
01-12-18, 20:15
Using a case gauge is fine for hoser ammo, you are just verifying that is will chamber.
It is much harder to eyeball a case gauge for consistency than it is to measure with a comparator.
If you are loading for accuracy, you will want to use your Hornday comparator to make sure you are getting a consistent set back. Something about consistency equaling accuracy.
If you want to "calibrate" your comparator, get a Go gauge and measure it with the comparator. IIRC, the Go gauge is the min headspace for the AR.
For increased accuracy, remove the expander ball (even on Forster dies) and use an expanding mandrel. Neck tension is the key.
You don't really need to crimp the neck. If you do, just remember that your are increasing chamber pressure and pay strict attention if you are operating near the upper limit of that powder. (MK262 clones)
For semi-autos, you want to full length size. Period.
Mixed headstamps can/will give you mixed headspace lengths. Fine for hoser ammo but not precision stuff. Remember that whole consistency equals accuracy thing.
If you want to load precsion ammo, go right to the Forster press. I no longer use my RCBS now.
I get less than .001 difference in headspace on my Forster with my 308 brass.
Yes, you can load precision ammo on a progressive press but it take some/alot of modification and knowing what you are doing.
I can't wait until you discover case and bullet runout.
Using a case gauge is fine for hoser ammo, you are just verifying that is will chamber.
I load precision .223 all day long and never owned or used anything other than a gun's chamber or a case gauge. I have NO problem at all using/getting equipment to make precision ammo or adding steps to the process. But there needs to be a payoff of some sort. I need a reason to be doing extra leg work.
Neck tension is the key.
I think I'm getting neck tension consistency from the LEE Factory Crimp Die. I know it dramatically increases accuracy for me, but I'm only guessing that it's due to neck tension uniformity.
You don't really need to crimp the neck. If you do, just remember that your are increasing chamber pressure and pay strict attention if you are operating near the upper limit of that powder. (MK262 clones)
In my process, I've seen no signs of increased pressure. I did a .223 crimp/chrono test years back with a variety of crimps and no crimp and could find no significant changes in velocity.
For semi-autos, you want to full length size. Period.
I like to full length size everything every time. Bolt gun and Gas gun.
Mixed headstamps can/will give you mixed headspace lengths. Fine for hoser ammo but not precision stuff. Remember that whole consistency equals accuracy thing.
The best groups I've ever shot in .223 have been mixed brass. .308, etc is a whole different story.
Yes, you can load precision ammo on a progressive press but it take some/alot of modification and knowing what you are doing.
Simple die selection gives me great ammo on my 550b. I single stage and arbor press for bolt gun.
I can't wait until you discover case and bullet runout.
I'm try to avoid runout, but shooting tangent ogive bullets makes it less critical. I took the worst runout rounds i could find out of a box of BH 168 smks and shot the group... expecting horrible accuracy. But they shot just as good as the straightest rounds. I think the "bad" rounds were running .007-.010" runout if I remember right.
The biggest cause of neck runout is when the expander is locked down off center and induces neck runout.
Below even the cheaper Lee full length dies have a expander that is reasonably centered that does not move in the collet clamp. Meaning if you do not have a runout gauge and clean the threads on the expander spindle and clamp you will produce better than average ammo. It is the RCBS, Redding and other brands that the expander can be locked down off center
https://i.imgur.com/QC9xK5D.jpg
If you want to spend a little more then the Forster full length benchrest die with the high mounted floating expander will reduce runout even more.
The Forster full length die holds and centers the neck of the case in the neck of the die when the expander enters the case neck and can not pull the neck off center.
https://i.imgur.com/Y7Iyv8o.jpg]nout.
And the Forster benchrest seating die holds the bullet in perfect alignment with the case and can not tilt and induce runout. And these dies are cheaper than redding.
https://i.imgur.com/MomXeUI.gif
Also if you lube the case neck by dipping the neck in powdered graphite it will greatly ease sizing with the expander and when seating the bullets.
https://i.imgur.com/CH3epH9.jpg
I'm try to avoid runout, but shooting tangent ogive bullets makes it less critical. I took the worst runout rounds i could find out of a box of BH 168 smks and shot the group... expecting horrible accuracy. But they shot just as good as the straightest rounds. I think the "bad" rounds were running .007-.010" runout if I remember right.
A full length resized cartridge is supported in the rear by the recessed bolt face and by the bullet in the throat. Meaning the case body and neck do not touch the chamber walls and gives the bullet wiggle room to be self aligning with the axis of the bore.
The military considers match grade ammunition to have .003 or less bullet runout.
Below with a full length resized case only the case shoulder contacts the chamber as long as the case is not warped and banana shaped. If the case has unequal case wall thickness the thin side of the case will expand more causing the case to warp. And this causes the base of the case to be no longer 90 degrees to the axis of the bore and push the rear of the case off center. Meaning full length resizing with adequate head clearance minimizes case mis-alignment with the bore. "The cartridge should fit the chamber like a rat turd in a violin case" ;)
https://i.imgur.com/RDNXFbN.png
https://i.imgur.com/Y3IiYL5.jpg
Below Mr. Salazar is explaining the benifits of "full length resizing" when asked about partial full length resizing that does not reduce case diameter enough for chamber clearance.
Reloading: Partial Neck Sizing
by German A. Salazar
http://riflemansjournal.blogspot.com/2010/06/reloading-partial-neck-sizing.html
"Now the last scenario, a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway."
Also if you lube the case neck by dipping the neck in powdered graphite it will greatly ease sizing with the expander and when seating the bullets.
https://i.imgur.com/CH3epH9.jpg
As always, great info and diagrams bigedp51! I didn't know this application media existed. I've been using imperial dry neck lube, applying it to the inside of the neck using a q-tip like a moron. Ordering some now.
As always, great info and diagrams bigedp51! I didn't know this application media existed. I've been using imperial dry neck lube, applying it to the inside of the neck using a q-tip like a moron. Ordering some now.
When you wet tumble with stainless steel media it removes all the carbon from the inside of the case neck. And graphite powder is nothing more than very fine ground carbon and the expander smears and spreads this carbon inside the neck recoating it. This carbon coating also helps keep the bullet from bonding to the case neck and increasing bullet grip over time.
I've been using imperial dry neck lube, applying it to the inside of the neck using a q-tip like a moron. Ordering some now.
I don't run any lube for neck expansion since it's on the down stroke. If I felt any sort of resistance on the press I would probably lube, but I don't thinks it's been a problem.
I don't run any lube for neck expansion since it's on the down stroke. If I felt any sort of resistance on the press I would probably lube, but I don't thinks it's been a problem.I've tried with and without lube. It is much smoother feeling with lube(on my rockchucker) but I can't say if this translates into any measurable benefit downrange. It just felt better to me.
That's the catch, will any of these extra steps help anything. Once I reloaded a batch of 100 rounds and did an experiment. I used my concentricity gauge to measure all 100 rounds. I went to the range and fired the most concentric 10 on paper, vs the worst 10...both groups were very similar.
Sent from my XT1565 using Tapatalk
I really strive to load good quality stuff with consistency but there's just no way on this Earth that I'd devolve the process in to what is about 99% of this thread.
I really strive to load good quality stuff with consistency but there's just no way on this Earth that I'd devolve the process in to what is about 99% of this thread.
Yeah. You have to pick your battles. There's no limit to the insanity.... Deburing flash holes, messing with primer pockets... weight sorting brass, etc. Those are the things I refuse to even consider.
I slowly added the steps necessary as I evolved from my early years of just loading FMJ basic ammo.
The real ass ache for me.. is SS media wet tumbling. That adds a lot of time and handling of brass. But I could never go back to working with marginally clean brass.
Why is that, markm?
Also, what would y'all (markm, anyone) say is the least amount of steps/work/processing that can be gotten away with for loading just "FMJ basic ammo"?
Why is that, markm?
Clean brass is so much nicer and neater to deal with. Your hands, dies, machines, etc. all stay cleaner. I decap with latex gloves and that's the only time I deal with dirty brass.
Also, what would y'all (markm, anyone) say is the least amount of steps/work/processing that can be gotten away with for loading just "FMJ basic ammo"?
Rifle is always a little more trouble than pistol due to the case lube removal. For me: decap, clean, lube/size/necksize, tumble off lube, prime, and load.
I could skip trimming on blaster ammo due to no expander ball, but I run all of mine in the Giraud because it chamfers the neck even if nothing gets trimmed.
I don't run any lube for neck expansion since it's on the down stroke. If I felt any sort of resistance on the press I would probably lube, but I don't thinks it's been a problem.
Some reloaders use a expander die on the up stroke of the ram to reduce neck runout. On the down stroke if the case has any extractor dings in the rim it can cause the case to tilt in the shell holder.
Does a progressive press change these dynamics? I do not understand why no lube on the down stroke especially with wet tumbled brass. I do not own or ever used a progressive so forgive my questions.
I use a Rockchucker press and Forster benchrest dies with their high mounted floating expander and lube my case necks. The neck of the case is held and centered in the neck of the die when the expander enters the case neck. And on the down stroke of the ram the expander can not pull you necks off center inducing runout.
Bill Murray
01-15-18, 18:03
As a new rifle reloader, I have already learned a lot by reading this discussion. Thanks everyone.
Markm, I have a question about the type of neck expander die you mentioned in Post #14.
I think it's just an RCBS .223 neck expander die. Every time I've forgotten the exact die, the subject comes back up. :p
Is this the type of die that you are referring to?
https://www.midwayusa.com/product/1011246697/lyman-neck-expander-m-die
Or this?
https://www.midwayusa.com/product/735762/rcbs-neck-expander-die-224
So far, I have been using a full length (not small base) sizing die. To help reduce expander ball friction, I have been lubricating the inside of the neck with a Q-tip using the same lube that I use for the case (Imperial Sizing Wax). But your suggestion for using the expander type die intrigues me as a way to reduce the cold working of the case neck.
If you want a good neck expander die then get the Lyman type "M" expander, you will have .003 neck tension or bullet grip. And bumping the case mouth on to the .226 step of the expander insures straight inline bullet seating.
https://i.imgur.com/ohIUcpd.png
As a new rifle reloader, I have already learned a lot by reading this discussion. Thanks everyone.
Me, too.
It's threads like this that keep me coming back here.
As a new rifle reloader, I have already learned a lot by reading this discussion. Thanks everyone.
Markm, I have a question about the type of neck expander die you mentioned in Post #14.
I have the second one. I have not tried the M die. The RCBS works for me well enough that I've not looked at other options.
When you take a balloon and squeeze it, it grows in length. Same with brass. The sizing die squeezes the brass back down so it grows IF you don’t have it adjusted to bump the shoulder back. I see this a lot when I’m setting up my full sizing die. The headspace grows until you screw the die down a little more to achieve the proper shoulder set back. Same with the seating die. If it’s screwed in too much, it can bump the neck back when seating a bullet.
The sizing die squeezes the brass back down so it grows IF you don’t have it adjusted to bump the shoulder back.
Interesting. I've never noticed this, but I never move my sizing die. How much length increase have you seen.
That could partially explain why XM193 brass requires SO MUCH trimming after firing the factory load. It's blown out so much that squeezing it down lengthens it perhaps.
The amount of upward brass flow in the die depends on the size of the chamber and the size of the die. Meaning the more the case is squeezed down in diameter in the die the longer the case will grow.
Example a small base die would squeeze the case down more before the die pushed the case shoulder back down.
https://i.imgur.com/wm05ArY.gif
Before I had gauges I would start with a .010 feeler gauge between the die and shell holder and work down until the case chamber freely.
https://i.imgur.com/7FfXhJ7.jpg
I just got a case gauge (Dillon) and am mucking around with some once fired and some prepped cases in it.
How on earth are y'all telling whether or not the cases are above or below the min/max headspace? It is SO close.
I can kind of tell, but it is by no means obvious, whether or not the case is in spec or not.
Also, the case mouth is shorter than the min; is this bad?
Use your finger nail if nothing else. Feel for the flick of the ridge on the high/low. It's not much, but believe me... if you don't get it below the max, your gun will not go into battery very well.. if at all.
And short necks are not a problem. Some FC brass comes REALLY short. Just grow it out by sizing and firing it.
Speaking of varying neck lengths, how does that effect neck tension? Does it matter or is neck length inconsequential as compared to neck diameter?
Also I have a Dillon .223 case gauge and rarely use it. I just went through a pile of fired .223 brass waiting to be resized and they all fit the case gauge. I don't find it gives me much information for setting up my fl sizing die when the unsized cases fit it anyway. I'm a relatively new reloader though so I might be missing something.
I just got a case gauge (Dillon) and am mucking around with some once fired and some prepped cases in it.
How on earth are y'all telling whether or not the cases are above or below the min/max headspace? It is SO close.
I can kind of tell, but it is by no means obvious, whether or not the case is in spec or not.
Also, the case mouth is shorter than the min; is this bad?
You use a case comparator to measure it. Like Hornady’s lock and load Headspace Comparator. The headspace guage only tells you if the round will fit in the chamber. Wrong tool for the job. The comparator clamps onto your calipers and measures from the datum line (center) of the shoulder.
I just got a case gauge (Dillon) and am mucking around with some once fired and some prepped cases in it.
How on earth are y'all telling whether or not the cases are above or below the min/max headspace? It is SO close.
I can kind of tell, but it is by no means obvious, whether or not the case is in spec or not.
Also, the case mouth is shorter than the min; is this bad?
I'm 67 and have chronologically gifted eyesight and I went to the Hornady cartridge case headspace gauge. Because of the larger digital numbers on my vernier calipers are very easy to see.
Below a fired Lake City 5.56 case in my Hornady gauge and much easier to see, since they do not make braille drop in case gauges.
https://i.imgur.com/H0SXHH8.jpg
The case mouth measurement in drop in case gauges is based off the shoulder location. If you measure OAL case length with vernier calipers you will get a more accurate reading. Meaning forget the small end of the gauge if you do not want to drive yourself nuts.
The big advantage to the Hornady gauge is you can measure a fired case. And many fired cases will not fit in a drop in case gauge. Meaning with the Hornady gauge you can "SEE" how much you are bumping the case shoulder back during sizing.
Got one of those... That's what all the measurements that started this thread came from.
I'm just wondering what a case gauge, such as the one I have, is used for, and how to read it.
[/QUOTE]
"Prepped": full-length sized, primed, and trimmed to proper case length.
Mean = 1.465595"
Median = 1.468"
Std. Dev. = 0.004535"
N = 21
[/QUOTE]
Don’t trim your brass until you are sure you have bumped the shoulder back adequately. I find when I set up the die to bump the shoulder back properly, I rarely if ever need to trim the cases. I’ll do it once maybe for uniformity. Then I’m gtg for the life of the brass.
Ok. Sounds good. I'm trimming length based off the shoulder to mouth dimension, versus head to mouth dimension. So it seems like I could potentially get better control over neck tension or how much of the bullet is in the case, doing it the way I do.
Got one of those... That's what all the measurements that started this thread came from.
I'm just wondering what a case gauge, such as the one I have, is used for, and how to read it.
twadsw01,
I use the Dillon case gauge to set up my sizing die and to quickly verify overall case length. Here is Dillon's video describing proper use of their case gauge to set up a sizing die:
https://www.youtube.com/watch?v=PIO37hANQlY
Dillon's video does not describe how to use their case gauge to check overall case length. If you do use it to check for OAL, do not push the case up into the gauge. Just insert the case into the gauge and place on a flat surface (primer pocket side facing down). The case's neck's edge should be between the milled section on the other side of the gauge if it is within SAMMI spec. Of course, if you trim shorter or longer (for whatever reason) then it may or may not land within the milled section.
Speaking of varying neck lengths, how does that effect neck tension? Does it matter or is neck length inconsequential as compared to neck diameter?[QUOTE]
longer necks give a greater contact surface with the bullet.... making neck tension more consistent (ideally). There are other issues that can wreck neck tension too however... harder brass, etc.
[QUOTE]Also I have a Dillon .223 case gauge and rarely use it. I just went through a pile of fired .223 brass waiting to be resized and they all fit the case gauge. I don't find it gives me much information for setting up my fl sizing die when the unsized cases fit it anyway. I'm a relatively new reloader though so I might be missing something.
The gauge is only useful on sized brass... for me anyway.
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