View Full Version : When does brass really expand in length?
So...I've seen numerous threads in various forums about the need to trim brass because it expands after firing.
I've measured brass before firing and then before resizing and found increase in length to be nominal.
When I measure after resizing, however, I find it has increased in length significantly.
It seems to me that the common knowledge that trimming is required due to case expansion after firing is incorrect.
Probably silly but just wondering what others have seen.
Specifically I am referring to .223/5.56 and full length resizing.
And yes, I lubed the cases.
oddballmkg
07-16-10, 03:04
First I have to say I’m not expert in reloading, but the length the case expands too is going to be control some what by the size of the chamber of the gun that it is being fired from. Along with how hot the load is and how many times the brass case has been used. Even to what type of die you used to size the brass with can affect the flow of the brass. Some brands of case will even last longer than others. I reload a lot of .223 and I trim my brass every time I size it. And I generally only use the case two times before I throw them a way. Because I’m not sure how many times the cases have really been used. I usually load my .223 at about 90 percent of what the max load calls out for. And I’ve only been able to get about 4 reloading though brand new rifle cases for .223. With pistol rounds I just keep using the cases until the case splits down the neck. My pistol ammo is also only load to about 90 percent of max loads because I shot a lot and do not feel its worth hammering a gun to death with hot loads.
It seems to me that the common knowledge that trimming is required due to case expansion after firing is incorrect.
Hi
It is not incorrect. It is just not a complete thought and process. If you measure brass expansion after firing, I would bet that you would find that it expands out a bunch but not much in length. But that outward expansion needs to be pushed back in to the correct size so when you size it, that pushes the brass back in and like a tube of toothpaste you squeeze, that forces material to the ends as the path of least resistance.
So the firing of the case and brass expansion leads to the necessity to resize. Since the firing cause the brass to change shape. When it is resized, that expanded brass becomes elongated brass.
The vast majority of brass stretch, in my experience, comes from pulling an expander ball out of the case mouth when you resize the brass.
Shooting causes a little stretch... resizing maybe a touch as well, but the expander ball is the mother.
My solution has been to REMOVE the expander ball and use a neck sizing die. I get many more loads out of my brass before needing to trim again.
Pumpkinheaver
07-16-10, 21:21
It stretches upon firing but it also stretches when you pull the expander button out of the case after resizing.
M855 and XM193 stretches like a mother upon firing. I can fire my handload, resize them, and they still don't need a trim.
With Mil ammo, that is never the case.
My solution has been to REMOVE the expander ball and use a neck sizing die. I get many more loads out of my brass before needing to trim again.
Mark this is the first I have ever heard of this approach. I am curious does this cause you any problems when seating the new bullet since the mouth is not open as much? Thanks
The vast majority of brass stretch, in my experience, comes from pulling an expander ball out of the case mouth when you resize the brass.
Shooting causes a little stretch... resizing maybe a touch as well, but the expander ball is the mother.
My solution has been to REMOVE the expander ball and use a neck sizing die. I get many more loads out of my brass before needing to trim again.
In my experience, this works when using the same brass in the same rifle. All chambers are not exactly the same.
First, you have to understand what causes the case to lengthen is brass flow. The thickest part of the case that contains the powder is the web which is at the base of the case, nearest the primer. As the case expands under pressure, brass flows forward as that's the path of least resistance. The case grows thinner at the web and thicker forward of the web and makes it's way to the neck. Eventually, the web develops a groove from the thinning and stretching and will separate there. Re-sizing the cases does not reverse the brass flow, so the case gets longer.
markm, be careful just neck sizing your brass without the neck expander. If the brass gets too thick at the neck, when the bullet is seated, the neck diameter of the case will be too large for the neck diameter of the chamber. This can cause dangerous spikes in pressure
markm, be careful just neck sizing your brass without the neck expander. If the brass gets too thick at the neck, when the bullet is seated, the neck diameter of the case will be too large for the neck diameter of the chamber. This can cause dangerous spikes in pressure
Interesting notion.... I'll have to think on that one for a bit. I'm doubtful it'd be a problem for me since I only load brass twice... But I still want to wrap my head around that idea.
I can't say with certainty, but I believe the whole "brass flow" concept is bogus. What I do know is that the majority of brass length increases come during resizing. It's as someone stated previously -- the case dimensions are displaced forward as the body is squeezed down in the resizer. The case stretches at the web, but I don't buy into the notion that brass turns plastic or liquid momentarily and then flows fwd.
Markm, have you taken measurements on case growth both w/expander ball and w/o? If so, what are the deltas? Did you lube the inside of your case necks at all or were they dry?
If you adjust your resizer to bump the shoulder just a couple of thousandths from a fired case dimension, you'll controll how much stretch/case growth you experience. If on the other hand you just screw die in to press until firm shellholder contact is achieved, you can end up bumping shoulders .006 - .008", and you most certainly will see excess stretching and ultimately, casehead separation. You can even test a few cases by taking a paper clip or a short section of bailing wire, bending the tip to 90 degress, and filing it sharp. Then see if you can snag the separation ring that might be forming -- no snagging, you're GTG. But if you feel the snag, realize that brass is at end of life and further reloads are unadvisable.
Mistwolf, how does utilization of an expander ball keep neck thicknesses in check, while omitting the use of an exp ball allow them to thicken?
First, you have to understand what causes the case to lengthen is brass flow. The thickest part of the case that contains the powder is the web which is at the base of the case, nearest the primer. As the case expands under pressure, brass flows forward as that's the path of least resistance. The case grows thinner at the web and thicker forward of the web and makes it's way to the neck. Eventually, the web develops a groove from the thinning and stretching and will separate there. Re-sizing the cases does not reverse the brass flow, so the case gets longer.
markm, be careful just neck sizing your brass without the neck expander. If the brass gets too thick at the neck, when the bullet is seated, the neck diameter of the case will be too large for the neck diameter of the chamber. This can cause dangerous spikes in pressure
mistwolf has it right...the brass will stretch the most depending on the where the case & chamber vary on the saami spec.
The tightest chamber one the fattest case will stretch much less than the vice-a-verca. You can watch this by how much you have to trim after every fl. This is a GOOD brass life indicator!!
I have gone to minimal full length on all my reloading after the br boys started doing it and winning....auto guns get the complete full length and tossed after 3-4 hot loads.
Thomas M-4
04-24-11, 19:24
The vast majority of brass stretch, in my experience, comes from pulling an expander ball out of the case mouth when you resize the brass.
Shooting causes a little stretch... resizing maybe a touch as well, but the expander ball is the mother.
My solution has been to REMOVE the expander ball and use a neck sizing die. I get many more loads out of my brass before needing to trim again.
This ^^^
I normally see about .005" stretch with a expander ball.
I just did a quick check on doing a full length resize on my press. It gave me a increase in length of .004-.005 on 10 differient pieces of brass.
On a related note measuring some range pick-up brass showed an overall length of varying between 1.48-1.52. Given the maximum length allowed is 1.760 it doesn't seem you need to trim each time.
mistwolf has it right...the brass will stretch the most depending on the where the case & chamber vary on the saami spec.
The tightest chamber one the fattest case will stretch much less than the vice-a-verca. You can watch this by how much you have to trim after every fl. This is a GOOD brass life indicator!!
I have gone to minimal full length on all my reloading after the br boys started doing it and winning....auto guns get the complete full length and tossed after 3-4 hot loads.
Stretch -- Yes. Flow -- No. There is a difference.
Markm, have you taken measurements on case growth both w/expander ball and w/o? If so, what are the deltas? Did you lube the inside of your case necks at all or were they dry?
Case length growth was never specifically quantified... just generally observed using my case guage.
What was dramatically reduced by ditching the expander ball was bullet runout.
Case length growth was never specifically quantified... just generally observed using my case guage.
What was dramatically reduced by ditching the expander ball was bullet runout.
I've found that as long as the interior of the necks are lubed, case stretch is minimal. That's using diluted Lee lube w/alcohol sprayed on cases in a ziploc and kneaded a la "shake and bake". Enough lube makes it into the interiors to lube them.
While I haven't made any effort to compare results, I've heard (and adjusted my dies accordingly) that if you adjust the sizer ball up high in the die, just below the neck, so that expanding takes place while the neck is still partially in the neck resizing portion of the die, runout is reduced compared to when the ball is positioned low in the die and the neck clears this portion before it's run over the expander. When thus adjusted runout measures between .000 - .002" IIRC. Just something to ponder......
The neck sizer squeezes the outside neck diameter down. Neck material gets thicker, and brass is work hardened, mostly on the outside. Neck expander increases internal neck diameter. Material gets thinner, but as it's pressed against the previously cold worked outer layer, it flows forward more. That's why cases lengthen more when both are used.
I don't make the claim that outside neck sizing only is bad practice. The whole purpose to sizing the neck is to get adequate and consistent tension on the seated bullet. For the average reloader, using an expander after sizing the neck is the easiest way to achieve this. When neck sizing without the expander, if all the brass has the same thickness and that thickness is right for the sizer and bullet, all is good. If the neck thickness varies, tension will vary and so will pressure and velocity and accuracy will suffer. (If the reloader is getting the accuracy wanted, there are no worries.)
Here is a quote from Varmint Al's website, an engineer who knows more about reloading than I ever will- "Most cartridge cases have a limited life because of high stress levels and the plastic deformations of the brass during firing and resizing."
http://varmintal.com/arelo.htm#Neck_Turning
Look at the animation (post #20)........
http://www.jouster.com/forums/showthread.php?10515-SMLE-Headspace-Problems/page2
So, you may say, "it's nominal......".
I say, "whatever."
As for case length.....
Well, after resizing.......it is what it is. If the brass is too long, you need to trim.
Why?
When an overlength case is chambered, the mouth or edge of the neck will come up against the throat (left, top) before the bolt has fully closed or the case shoulder has contacted the chamber (left, upper middle). The camming action of the bolt is so powerful that it will actually crimp the case mouth fully into the bullet (left, lower middle) and wedge the case so solidly between the bullet and the throat that the neck cannot expand to release the bullet. Chamber pressures in this situation can and most certainly will go dangerously high (left, bottom).
Read more: http://www.hornady.com/ballistics-resource/internal
I trust that you already know why you are resizing your used brass.
Aloha, Mark
I've found that 5.56 brass ends up being longer than .223 brass, I guess that makes sense based upon the difference between .223 & 5.56.
I've found a good number of the brass that I've tried are actully shorter than the recommended trim length. For "blasting" loads I just load them without trimming.
I've recently started trimming by Lake City brass to 1.760 Vs 1.750 and seem to get better results from my Noveske SS barrel.
So what length do you guys trim your brass to?
There's a guru on ARFcom... WerBorg. I wish he'd post over here. That guy knows a lot about hand loading. He is one of the reasons I don't use the expander ball on .223 brass.
I've found that 5.56 brass ends up being longer than .223 brass, I guess that makes sense based upon the difference between .223 & 5.56.
I've found a good number of the brass that I've tried are actully shorter than the recommended trim length. For "blasting" loads I just load them without trimming.
I've recently started trimming by Lake City brass to 1.760 Vs 1.750 and seem to get better results from my Noveske SS barrel.
So what length do you guys trim your brass to?
I trim to 1.750" +/- 0.003"
I've been monkey ****ing with the possom hollow on .223. But I'm going to get a case holder for the Wilson/Sinclair hand trimmer and start getting the job done RIGHT! :mad:
I've been monkey ****ing with the possom hollow on .223. But I'm going to get a case holder for the Wilson/Sinclair hand trimmer and start getting the job done RIGHT! :mad:
I was looking at the Wilson/Sinclair trimmer too, looks to be top-notch. What kind of trouble were you having with the possom hollow trimmer?
The possum is ok. But it doesn't cut consistently... I end up with +/- .010 regularly. 1.74 to 1.75 and some longer. And it doesn't cut straight all the time because it indexes off the shoulder. It has to have enough play to let the body spin on the brass so you can end up holding it crooked in the cutter body.
One of the guys on arf told me to twist the brass in the cutter and that helps a lot, but you still are getting mediocre results. Plenty good enought for bulk practice ammo... don't get me wrong.
But going from that to the Wilson/Sinclair with the mount, stand, and shark fin is a whole different ball game. It does such a nice job, I don't mind trimming manually.
Stretch -- Yes. Flow -- No. There is a difference.
it's all relative...even the size of the fl die comes into play.
the brass flow is during the firing stage...if a small cartridge in sloppy chamber fires, the brass has to expand and flow to seal the chamber alot more compared to the same cartridge that is on the larger saami side.
Then when you resize that small cartridge that is now the size of the sloppy chamber, it's going to stretch more than the fatter one to get it back to correct size.
Forget about the expander ball for a moment in all of this...its happening in the case body as well and why some brass gets overworked more than others.
On my auto guns, I full length with the die all the way down...on my bolts, I will adjust the die (with shims) to where the case is completely full lengthed (for the particular gun) without the die adjusted to the bottom of the press. You can test this by removing the firing pin assembly and just use the bolt body to feel for tension when closing on the sized case.
I would also like to know what length others trim to, if you guys wouldn't mind sharing.
Re: neck sizing.
Against all internet advice, I used a Lee Classic Loader for hundreds of rounds of brass that was fired out of my rifle and went right back into my rifle. Fired once out of the box, neck sized for two reloadings then tossed. Never was a problem.
markm, be careful just neck sizing your brass without the neck expander. If the brass gets too thick at the neck, when the bullet is seated, the neck diameter of the case will be too large for the neck diameter of the chamber. This can cause dangerous spikes in pressure
This has still been simmering in the back of my head....
Is the reason for case neck turning?
I was going to say you're nuts because the benchresters often don't use an expander ball.... but then I thought maybe they're turning the necks down for this reason....
This was previously a non issue as I was only loading brass 2 times.... But Pappabear bought some nice Lapua brass that I plan to get more loads out of.
From 30 years of experience in reloading rifle and pistol rounds! Yes rifle rounds expand in lenght when fired and sizing them. Now what I found is the load makes quite a difference in how much growth you see after firing as well as your trim too length when your loading effect how much growth you'll see! Setting your trim length as close to your chamber demensions will limit the growth of the case! For my AR's both 5.56mm chambers I use 1.760" trim lenght. For a Rem .223 use a trim length of 1.750-55" . Do this and use moderate loads an you will probably not see any growth in case length! This is not set in stone! Some cases are soft and will grow in lenght no matter what you do just they way it is!:D Normally my AR cases grow about .005" over trim too length. I shoot alot of XM193 and those cases grow as much as .015" after firing over the trim length of 1.760"! PS measure your cases before you decap/size to find out how much they have grown!
The biggest reason for case lengthening is due to sizing. If you have a loose chamber and it stretches out more on firing, when you size it, it has to push the brass in more which will cause more "flow". The sizing is the culprit but the brass quality, chamber dimensions, and charge size (light load versus heavy load) all affect how much work the sizing die has to do.
This has still been simmering in the back of my head....
Is the reason for case neck turning?
I was going to say you're nuts because the benchresters often don't use an expander ball.... but then I thought maybe they're turning the necks down for this reason....
This was previously a non issue as I was only loading brass 2 times.... But Pappabear bought some nice Lapua brass that I plan to get more loads out of.
Neck thickening is a minor problem but one that can have dire consequences if not checked. Thick necks are mostly a problem with chambers cut to tight dimensions. 5.56 chambers are cut to generous dimensions.
Neck turning is mostly for truing up the neck and to ensure the thickness is the same around the entire circumference. Some cases start with thick necks. If so, they need to be turned before being used in chambers with tight neck dimensions.
My original warning was intended to be general, that a reloader shouldn't use neck sizing without an expander for all rifles without checking for certain situations.
Check to see if this unsafe condition exists. If not, press on. Thickening of necks from repeated firing is usually a slow process and is critical in chambers with tight necks. It's less of a problem with factory cut 223 chambers and even less so with 5.56 chambers.
If neck sizing without expander works gives good results, by all means use it! I don't say it's wrong or even less correct than other methods. Whatever method used for any step in reloading, just know what to look for and stay safe.
Benchresters have developed a way to never resize their cases. They match chamber neck dimensions, case neck thickness and bullet diameter so that when the shot is fired, the neck expands just enough to release the bullet, but the neck dimension keeps the case neck from expanding so much it needs to be resized. When reloading, they simply replace the primer, powder and seat a new bullet. Of course, when doing so, they avoid maximum loads to minimize case stretch and the cases are fire formed and can only be used in that chamber.
Bottom line- There is no method of resizing cases that is best or correct for every situation. Just know what the advantages and disadvantages are for the method chosen and avoid potentially dangerous combinations
Let me add that one must check for thick necks when using expander balls as well
I hear you. It's something to keep in mind when we start getting more loadings out of our brass.
From 30 years of experience in reloading rifle and pistol rounds! Yes rifle rounds expand in lenght when fired and sizing them. Now what I found is the load makes quite a difference in how much growth you see after firing as well as your trim too length when your loading effect how much growth you'll see! Setting your trim length as close to your chamber demensions will limit the growth of the case! For my AR's both 5.56mm chambers I use 1.760" trim lenght. For a Rem .223 use a trim length of 1.750-55" . Do this and use moderate loads an you will probably not see any growth in case length! This is not set in stone! Some cases are soft and will grow in lenght no matter what you do just they way it is!:D Normally my AR cases grow about .005" over trim too length. I shoot alot of XM193 and those cases grow as much as .015" after firing over the trim length of 1.760"! PS measure your cases before you decap/size to find out how much they have grown!
I've been wondering about the trim length for a 5.56 chamber. I have a Noveske stainless recon carbine and found that I get a bit better performace when I trim to 1.760.
I've found enough of a difference in my case prep that I'm going to twitch between powders to see where I get better results. I sort of guessed at trimming to 1.760 due to the type of chamber I have.
low drag
Yep that's the difference between 5.56mm an Rem .223 ! Very easy to see if you shoot XM193 and say PMC Rem 223! I've found that Rem .223 usually measures out at 1.740-.1750" after being fired!:D
low drag
Yep that's the difference between 5.56mm an Rem .223 ! Very easy to see if you shoot XM193 and say PMC Rem 223! I've found that Rem .223 usually measures out at 1.740-.1750" after being fired!:D
Thanks for the info.
This is one of those threads that I can say I've learned something.
I'm off to the range this morning to try out a couple of loads, trimmed to 1.760 of course.
I've been wondering about the trim length for a 5.56 chamber. I have a Noveske stainless recon carbine and found that I get a bit better performace when I trim to 1.760.
I've found enough of a difference in my case prep that I'm going to twitch between powders to see where I get better results. I sort of guessed at trimming to 1.760 due to the type of chamber I have.
http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage
Sinclair sells a leaded steel insert that you insert in a overly trimmed and sized case. The insert sticks out well beyond the 1.760" value and as you gently insert the cartridge, the insert butts up against the neck and slides down into the case. The neck tension from the sized case keeps it from slipping further.
Gently remove the cartridge and measure your chamber length. Now you can set your trimmer to trim cases to just below this value and not constantly overtirm to 1.750" or whatever.
Chamber specs are bigger than ammunition specs. They have to be so that a minimum cut chamber can still accept a max length cartridge that's still in spec. So while manuals tell you 1.760"is the max case length, I'd venture to guess the minimum specs on a reamer would result in a chamber cut that would provide at least a couple thousandths clearance over that dimension, maybe more. When we trim to 1.750" we're just overdoing it, althogh I don't know if we're harming anything. At most we're probably giving a place for carbon to accumulate that we later take effort to scrub out with a chamber brush.
In case you're wondering, the leaded steel insert is soft enough that it won't scratch or mar you chamber/neck in usage.
http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage
Sinclair sells a leaded steel insert that you insert in a overly trimmed and sized case. The insert sticks out well beyond the 1.760" value and as you gently insert the cartridge, the insert butts up against the neck and slides down into the case. The neck tension from the sized case keeps it from slipping further.
Gently remove the cartridge and measure your chamber length. Now you can set your trimmer to trim cases to just below this value and not constantly overtirm to 1.750" or whatever.
Chamber specs are bigger than ammunition specs. They have to be so that a minimum cut chamber can still accept a max length cartridge that's still in spec. So while manuals tell you 1.760"is the max case length, I'd venture to guess the minimum specs on a reamer would result in a chamber cut that would provide at least a couple thousandths clearance over that dimension, maybe more. When we trim to 1.750" we're just overdoing it, althogh I don't know if we're harming anything. At most we're probably giving a place for carbon to accumulate that we later take effort to scrub out with a chamber brush.
In case you're wondering, the leaded steel insert is soft enough that it won't scratch or mar you chamber/neck in usage.
Thanks for the info. I've just returned from the range and confirmed that trimming to 1.760 gives better results than 1.750. Also loads with Varget perform better than loads with AA #2520 for loads with same brass/trim length/bullet/OAL. For my best groups of 5 (yeah, yeah I know) at 100 yards I get 4 touching/stringing and one pulled to give me a group size of just under 1". That is most likely me, a 5X optic is not enough to hold 1/4" at 100 yards. Maybe some of you guys can do it but I can't.
Both the Varget & AA 2520 load with 68 grain Hornady bullet gave me better results than Hornady 75 gr match ammo.
I have a bit of Federal GMM 69 & 77 gr to try but they did about as well as the Hornady 75 gr match the last time I checked. My hypothesis is the match ammo from Federal & Hornady is loaded to .223 length spec not NATO length spec.
All this shot from a Noveske SS 16", it's the VTAC model on an LMT lower with a 2 stage match trigger & Leopold Mark 4 1.5-5X in a LaRue mount using bags/rest for front and back of the carbine.
When we trim to 1.750" we're just overdoing it, althogh I don't know if we're harming anything.
I bet the reason we "overtrim" goes back to the old days of manual trimming. Overtrimming means you don't have to trim each time -- you over do it once and then you are good for a few shots...
The one thing I'd caution folks against is, if you are getting too greedy and are trying to match the case length to the neck/throat junction, make sure you are taking headspace into account.
Remember that prior to case's firing the shoulder of the cartrdige isn't resting up againt the shoulder of the chamber. When the firing pin hits, it pushes the entire case forward to the point where it stops against the chamber's shoulder, and the neck is being pushed forward as well going along for the ride. If you adjusted trim length to be spot on against the neck/throat junction and haven't provided any clearance, realize now that the tip of the neck may be pinched by the throat. This can cause big pressure spikes and that's the main reason we trim to begin with.
If you adjust your sizer to bump resized shoulders say .003" from a fired case dimension, I'd set my trimmer to cut the neck back at least .005-.006"" from the neck/throat junction point, that ought to give you enough clearance and safety margin.
For my best groups of 5 (yeah, yeah I know) ....
Don't sweat it, 5-shot gtoups are fine. Don't obsess over having to shoot 10.
My hypothesis is the match ammo from Federal & Hornady is loaded to .223 length spec not NATO length spec.
What are the differences in the spec?
Don't sweat it, 5-shot gtoups are fine. Don't obsess over having to shoot 10.
What are the differences in the spec?
(I'm not stress'in over the 5 shot groups, just keeping the peanut gallery at bay) ;)
My understanding (take with a grain or two of salt) is the 5.56 is longer in the neck area/lead than .223. Of course the 5.56 is loaded to higher presures than .223 and hand thicker brase etc.
I've found all my brass that is head stamped Lake City or some NATO version come out much longer than a .223 piece of brass. I've seen 1.755 - 1.770 on NATO while only 1.740 on .223, after firing and sizing.
I'm sure I've seen a post here at m4c on this topic. It'll test my searchfoo to find it but will give it a shot.
Either way this has been a great learning experiance for me.
If using a conventional sizer with expander ball, getting some lube inside the case necks (or most of them) will reduce the stretch. Using a gallon zip-lock bag and spray lube makes this pretty easy. Use the wrong lube, however and you get dented shoulders. Hornady One
Shot works well for me.
ETA: IMO you will go nuts trying to trim to 1.760" (or longer) for a gas gun. Some brass will not run that long after the first firing, nor will factory new brass.
(I'm not stress'in over the 5 shot groups, just keeping the peanut gallery at bay) ;)
My understanding (take with a grain or two of salt) is the 5.56 is longer in the neck area/lead than .223. Of course the 5.56 is loaded to higher presures than .223 and hand thicker brase etc.
I've found all my brass that is head stamped Lake City or some NATO version come out much longer than a .223 piece of brass. I've seen 1.755 - 1.770 on NATO while only 1.740 on .223, after firing and sizing.
I'm sure I've seen a post here at m4c on this topic. It'll test my searchfoo to find it but will give it a shot.
Either way this has been a great learning experiance for me.
I'm aware that the NATO chamber has a longer throat and shallower leade, but that's all ahead on the neck/case mouth point As far as a I know, case lengths and neck lengths are the same between the two. But I'll admit, I haven't studied this aspect as much so I may be misstating here.
If using a conventional sizer with expander ball, getting some lube inside the case necks (or most of them) will reduce the stretch. Using a gallon zip-lock bag and spray lube makes this pretty easy.
Yeah... I'm aware of all that... and don't want the ass ache. It's really the reduction in bullet runout that keeps me from using the expander ball on .223.
I'm aware that the NATO chamber has a longer throat and shallower leade, but that's all ahead on the neck/case mouth point As far as a I know, case lengths and neck lengths are the same between the two. But I'll admit, I haven't studied this aspect as much so I may be misstating here.
Yeah. Brass is essentially the same. It's the weapons chamber that has some differences... and that's a whole other debate.
jamrt
Good point! This is why as a reloader one must be very awhere of the signs of pressure and use a chrony! Brass doesn't always show pressure signs but a chrony will tell you! Once you laoded long enough you can figure what your velocities should be with a particular powder charge ! If your chrony is showing higher velocities then you should be getting then you know somethings not right with the load! :D For those here that have many AR's and reload remember one thing that load may not be right for all of your AR's as every gun is different! Especially if your running hot loads!
Carbide sizer buttons are available for Redding dies. For an AR, I just push them into a Gracey trimmer that is set to trim to max length. That way all the cases are the same length over time.
...Of course the 5.56 is loaded to higher presures than .223...
We don't know this to be true. SAAMI & NATO use different spec sensors & methods to measure pressure. As the 223 achieves the same velocities it's likely they are loaded to similar pressures.
I have 223 & 5.56 ammo loaded by Federal, both using the 55 gr bullet. Compared side by side, the bullet in the 5.56 is loaded to a longer overall length.
With the longer leade of the 5.56 chamber, the shorter 223 has a longer jump before engaging the rifling. This lowers the effective pressure compared to firing the same ammo in the 223 chamber with a shorter leade. It's possible that if the bullet of the 223 was loaded to a longer OAL to match the leade of the 5.56 chamber, pressures would be nearly identical.
It's also possible that if 5.56 ammunition was seated deeper to the OAL of the 223 it would be perfectly safe to fire in a 223 chamber.
The reason it's possible 5.56 ammo will generate too much pressure in the 223 chamber is because with the longer OAL the bullet might be long enough to engage the rifling when the cartridge is chambered.
It's very possible both types of ammunition actually generate similar pressures when fired in their respective chambers.
I am uncertain if the case length is longer for the 5.56
I am uncertain if the case length is longer for the 5.56
I've never found it to be. But I've seen some Federal Bulk pack .223 with very short case lengths. Like 1.73"
I've never guaged a piece of M193 or M855 that exceeded 1.75.
It's really the reduction in bullet runout that keeps me from using the expander ball on .223.
Ditto. Redding body die + neck die of your choice induces .001" run out or less.
Also helps with limiting stretching as a side benefit. Most occurs pulling the expander ball back through in my experience.
I just read a comment from a google search on setting up my Redding Type S die for 308. I recognized the guy as pretty experienced from another forum too.
Basically the expander ball can pull a case neck out of "true". This can be helped with a bushing die that doesn't force the expander to rip out of the case so friggin hard.
Again, much of the exp ball drag isues can easily be mitigated.
(1) Most exp balls are too big in diameter, producing neck tension around .001". Polish the ball down with a stone and finish w/crocus cloth until ball provides .003" neck tension. Less drag that way.
(2) Lube the case necks. You're already tumbling cases after resizing is complete to remove the lube, so why be afraid to get some in the neck? Just use a pump spray lube, a big ziploc and toss them around in there a bit. Enough lube will migrate to the neck interiors and you'll get less drag.
(3) Adjust expander so it sits high up in the die and the neck is running over it while it's still being supported in the die's neck on the downstroke. Forster allows you to adjust in this manner, as does Lee. Not sure about the others.
The good thing about exp balls is that when you're done you have a nice, round concentric neck on the interior. Take the ball out of the equation and the inconsistencies get displaced to the interior of the neck, right where you don't want them. Doing the above three steps produces cases with runouts of .001" or less. Not sure how you're going to get better than that, but if you need that added level of precision, go for it.
Those are all valid points. But I guess my issue isn't SO MUCH with the expander ball... as I plan to run it in my Redding Type S Full length sizing die with neck bushing...... as it is with how far some dies squeeze the neck down before ripping the ball back out of the case.
I pulled the expander ball out of my 308 die and measured the neck size. I forget the exact measurement off hand, but it was squeezing the neck down like 0.010" below final actual size! :eek:
When I tried to use my neck expander die on that brass it was deforming the friggin sides of the case neck. :mad:
This is why I ordered a bushing style full length sizer for 308. There's just NO NEED to size the necks down that far and then rip a ball back out of it.
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