.223 neck size only on a Semi?

P

PolarFBear

New member
I now have my .223 battery complete. A Colt AR Sporter, Ruger Mini-14 and a Savage bolt action Hog Hunter. I full length size for the Colt and never shoot the "safe-queen" Ruger. My question is can I neck size for the Colt? I realize rounds can NOT be interchanged with the bolt action Savage. My thinking is since the rounds are to be only used in a single chamber, the Colt, is full length sizing mandatory.
 
PolarFBear said:
I now have my .223 battery complete. A Colt AR Sporter, Ruger Mini-14 and a Savage bolt action Hog Hunter. I full length size for the Colt and never shoot the "safe-queen" Ruger. My question is can I neck size for the Colt? I realize rounds can NOT be interchanged with the bolt action Savage. My thinking is since the rounds are to be only used in a single chamber, the Colt, is full length sizing mandatory.
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You should full length size any semi auto.


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My question is can I neck size for the Colt?
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Yes you can, but you better tape a cleaning rod around the barrel so you can use the cleaning rod to knock the cases out when they don't extract.

Clearance between the case and chamber is critical for proper feed and extraction. Full length resize always for all semi automatic mechanisms.
 
"you better tape a cleaning rod around the barrel so you can use the cleaning rod to knock the cases out when they don't extract."

The more important issue is failure of the bolt to fully close and lock. While unlikely, there is a possibility of an out of battery ignition which is serious BAD ju-ju.
This might be OK for your Colt AR -- if it's similar to mine. My Colt's chamber is so sloppy, it will easily chamber improperly resized ammo that chokes every other AR on my rack.
 
If he is neck sizing rounds that have been shot out of the same rifle, he should be fine. The cases are fire formed to his chamber.


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No, no, no, and no! My question is why would you want to neck size a semi auto? Some semi chambers even require small base dies.
 
If he is neck sizing rounds that have been shot out of the same rifle, he should be fine. The cases are fire formed to his chamber.
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Not after a few firings. Even bolt gun has difficulty closing the action.
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^^^^^^^^^^THAT^^^^^^^^^^^

But to expand on that a little . Even one firing could cause the case to expand enough to cause "some" resistance when chambering the next time . If so some semi auto don't even come close to having the same camming action/force when the bolt is locking up as bolt guns do . This can cause the bolt not to fully close do to the poor cam leverage of most semi auto bolts .

Now that said , I did some test that showed the force of the complete BCG slamming home can and will set back the shoulder a little . My test showed anywhere from .0005 to .0015 and I believe I had one case set back .002 but the average was between .0005 & .0015 . Now this would allow the cases to be forced into the chamber . How ever that force is only setting back the shoulder and does not account for the body of the case . I'd expect after the second or third fringing the diameter/fatness of the cases would start causing chambering issues even if the BCG flying home was adequately pushing the shoulders back .

I recommend FL sizing each time when loading for semi autos even if it's minimal sizing like I do . I use FL bushing dies along with the proper competition shell holders and only set the shoulders back .003 . Which taken as a whole works the brass minimally as apposed to a standard FL die and standard shell holder .
 
I think it is tempting fate to neck size for any self-loader. It increases feed resistance because the case has to align more perfectly with the chamber to slip into it. Some AR owners report having to use a small base die to FL resize or they get some feed failures. I don't know why that happens, but it does. I can only imagine that if they neck-sized for these picky guns, they would have trouble even single-loading from a SLED. In the Garand and M1A and other .30 cal floating firing pin guns, the slamfire possibilities can be significant enough that any increased feed resistance is important to avoid. The AR doesn't do that so easily, but why tempt fate?
 
There is one problem associated with semi-autos that has not been mentioned, so I thought I would bring it up.
Due to the fact that the fired case can be pulled from the chamber when there is still pressure the case can be elongated during extraction. This certainly doesn't happen in every rifle under all conditions but it is possible.
I like the idea of neck sizing my 223 cases and I am going to try it to see how well it works. I have my doubts but reloading is about trying different things to see what works for you in your gun. I will report my findings when I have completed the tests. Whatever my results are will not be a definitive answer for all rifles under all conditions. My advice is that if you are curious, give it a try. See if it works for you.
 
Even if it is possible to neck size brass in a semi automatic and get away with it occasionally, why try? .223 brass is cheap, you can bump the shoulder back with a FL die .004 and if uniform necks or neck longevity are what you are after, just anneal it.

Personally I quit annealing my AR .223 brass because the heads are so chewed up by the 7th firing I toss them anyway
 
"...realize rounds can NOT be interchanged with the bolt action Savage..." More of a 'maybe' thing vs 'cannot'. Also a 'most likely not' thing. Isn't going to bother anything if you try it though. No safety issue. Mightbe a chambering issue that you'll find out instantly.
Mind you, AR's tend to be a bit harder on brass than any bolt action. You're probably not using the same bullet in both anyway.
When neck sizing only, sooner or later you'll have to FL size 'em no matter what else you do.
"...when there is still pressure..." The bolt does open on any rifle until the pressure is gone.
 
CAUTION!

shootistPRS said:
I like the idea of neck sizing my 223 cases and I am going to try it to see how well it works. I have my doubts but reloading is about trying different things to see what works for you in your gun. My advice is that if you are curious, give it a try. See if it works for you.
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I understand your experimental thinking, but given the added risk of out of battery firing (OOB-firing), extra safety precautions are important to observe in this experiment. Board member Hummer70 was once involved in an OOB-fire investigation in which the soldier to the right side (ejection port side) of the gun that had the OOB-firing in was killed. IIRC it was by a bolt fragment (these events usually gas cut the bolt face perimeter apart or blow the ejector loose or both), but if Hummer70 sees this, he can clarify.

The risk of OOB-firing is not as high in the AR as in .30 Cal and 7.62 military semi-auto designs, but it isn't zero with any floating firing pin gun design. It will be some number of standard deviations away from the norm but we don't know exactly how many and it will likely be fewer than for, say, turning the barrel into a banana peel.

Using neck sizing-only in a bolt gun relies on tactile feel of the bolt closing to alert you when repeated firing has caused the cartridge fit to start get too snug and that you need to perform a full length sizing cycle before returning to neck sizing again. The semi-auto takes away that tactile heads-up, and over-snug fit is a primary cause of OOB-firings.

So, given that you want to risk OOB-fires:

Make absolutely certain nobody is to the right of you on the range when you shoot these rounds; not ever. This experiment is outside the military operating design parameters and function testing, for which new ammunition with new, never-fired cases are always assumed to be used. OOB-fires are statistically distributed events that usually are a number of standard deviations from the norm. So treat any success you experience as annecdotal evidence. You could have 2000 of them work just fine, and then have the OOB on number 2001 or anywhere else along the way or after. Murphy's law says it will be right about the time you get comfortable with the idea this is an OK practice.

Make sure you are wearing safety glasses and extra good hearing protection. OOB-fires throw fragments and let gas loose closer to your ear than the muzzle is.

It should go without saying that you don't let anyone else shoot these loads, especially not minors who can't give informed consent to take the risk and who can't be counted on to have enough self-control discipline to make sure nobody is to the side of the ejection port when they fire it.
 
My only contact was a guy who made the transition from factory to reloading. His mentor recommended neck sizing for target ammo, most likely under the misapprehension that he would be shooting a bolt action like 95% of the F Class shooters there did. (I was the outlier and I don't neck size for my target auto, but he didn't ask me.)

So he got to sit out the next match because his ammo, not previously tested, would not chamber.
 
But to expand on that a little . Even one firing could cause the case to expand enough to cause "some" resistance when chambering the next time . If so some semi auto don't even come close to having the same camming action/force when the bolt is locking up as bolt guns do . This can cause the bolt not to fully close do to the poor cam leverage of most semi auto bolts .

Now that said , I did some test that showed the force of the complete BCG slamming home can and will set back the shoulder a little . My test showed anywhere from .0005 to .0015 and I believe I had one case set back .002 but the average was between .0005 & .0015 . Now this would allow the cases to be forced into the chamber . How ever that force is only setting back the shoulder and does not account for the body of the case . I'd expect after the second or third fringing the diameter/fatness of the cases would start causing chambering issues even if the BCG flying home was adequately pushing the shoulders back .
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Do you realize that what you were doing with a zero tolerance cartridge was increasing bolt thrust? For a mathematic treatment of this I recommend reading Professor Boatright’s papers on this.

Steel Support for the Brass Cartridge Case by James A. Boatright

http://www.thewellguidedbullet.com/pdfs/SteelSupportfortheBrassCartridgeCase.pdf


Yielding of Brass Case Walls in the Chamber by James Boatright

http://www.thewellguidedbullet.com/pdfs/YieldingofBrassCaseWallsintheChamber.pdf

If the math is too difficult, basically what Professor Boatright is showing that unless you are stretching the cartridge case, you are maxing out the bolt thrust. I recently re read his papers, having missed the point earlier, and I totally agree. To reduce bolt thrust by case stretch there has to be clearance between the cartridge shoulder and the chamber shoulder. Of course the case and chamber have to be sticky enough to grab. Chrome chambers would increase the bolt thrust because chrome reduces chamber friction. Oils and greases would reduce friction even more than a chrome coating. With a case shorter than the chamber, the firing pin pushes it forward in the chamber, the primer ignites, and then, the front of the case sticks to the chamber. Then as pressure builds, the case carries load by side wall stretching. The case sidewalls are stretched by the amount of clearance there was at the time of case adherence. Since the case is carrying load, by being stretched, some of that load is removed from the bolt lugs.

Now if you have a crunch fit case, such as what you were doing, or a neck sized case, while the case will adhere to the chamber, it won’t stretch, thus maximizing the amount of bolt thrust. It has to be equal to the bolt thrust of a lubricated cartridge, perhaps more.

There are many who worry about increasing bolt thrust, and they should be made aware that neck sizing increases bolt thrust to the maximum possible amount.
 
Do you realize that what you were doing with a zero tolerance cartridge was increasing bolt thrust?
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I think I know what you're saying but not sure it applies to what I was doing . First I did not have zero tolerance . The cases were FL sized bumping the shoulders back .002 to .003 . Now having a measurement of those sized cases from head to datum point I chambered the cartridge by Letting the BCG fly home stripping a round from the magazine . I then extracted the round and measured the cartridge from head to datum point again using the same tools I used to measure originally . The average additional shoulder set back from just chambering the round was about .001 with a few being more and a couple being less . If I were to chamber the same round again I would get set back again of about the same avg . If I repeatedly chamber the same cartridge The set back would continue until there was a head clearance of .006 to .007 at which point the shoulders no longer were getting pushed back any measurable amount .

I did these test with multiple AR rifles ( 3 ) using multiple brands of brass ( 4 ) with multiple bolt configurations ( complete bolt , stripped bolt and with and with out ejector or extractor ) The results were virtually the same regardless of which test rifle case or bolt configuration I used .

Hope that helps :)
 
I think I know what you're saying but not sure it applies to what I was doing . First I did not have zero tolerance . The cases were FL sized bumping the shoulders back .002 to .003 . Now having a measurement of those sized cases from head to datum point I chambered the cartridge by Letting the BCG fly home stripping a round from the magazine . I then extracted the round and measured the cartridge from head to datum point again using the same tools I used to measure originally . The average additional shoulder set back from just chambering the round was about .001 with a few being more and a couple being less . If I were to chamber the same round again I would get set back again of about the same avg . If I repeatedly chamber the same cartridge The set back would continue until there was a head clearance of .006 to .007 at which point the shoulders no longer were getting pushed back any measurable amount .
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I see what you were doing, you were measuring case shoulder set back due to chambering forces. In the 1947 American Rifleman article Accuracy factors in Rifle Mechanisms author Melvin Johnson observed the same phenomena, but he called it "drive-in".

Setting the shoulder back on the bench does not increase bolt thrust when the cartridge is fired. What you did not notice is that due to the force of chambering, the increase in clearances between the case and chamber, above that which you set in your sizing die, that increased case stretching above that induced by sizing alone.
 
Hey, Metal,

When you were doing the experiment, did you notice any change in COAL? I wonder whether the inertia force, when the cartridge abruptly stopped in the chamber, would pull the bullet out a bit. Thanks.

-TL
 
tangolima : Unfortunately I did not measure that and wished I had . I do how ever consider my self to be reasonably observant and don't recall any significant bullet movement . I'd like to think I would have noticed any large movement but the bullets could have moved a few thousandths and I don't think I would have noticed .
 
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