.223 case sizing question

[jmac2112]

I have an AR-15 that I built myself using a barrel with a .223 Wylde chamber (in case that's relevant).  I checked it using Forster gauges (5.56 Min and Max), and everything checked out.  I've loaded and shot about 300 rounds, and there have been no problems at all.  I should probably just relax and enjoy my rifle, but something is bothering me....

 

I have a Dillon case gauge that I used to set up my Dillon sizing die (in a Lee single stage press with a Lee shell holder).  After I size a case and put it in the gauge, it appears to the naked eye that the top of the case head is flush with the cut-out portion of the gauge (I'm sure that's not the proper terminology).  However, I recently decided to use a small straight-edge to see if the case heads were indeed flush with the gauge, and they are not.  They're proud of the gauge by just the tiniest bit, maybe no more than .001".  I have tried screwing in the die a little more, but it doesn't make any difference.  This is as much as the die is going to size the cases unless I start modifying things.  

 

So, my question is, what should I do?  I could take .001" off the top of the shell holder and try again.  That seems like the obvious solution, but is there a better way?  Is there a way to determine the best length for my chamber?  I've read that you can use a comparator to check the case-head to shoulder distance of a casing fired in your gun and then size to .003"-.004" shorter than that.  I've also heard that that only works for bolt guns, not autoloaders.  Or should I just stop worrying and go shoot my gun?

 

Thanks in advance for any advice!

 

John

 

[MadBomber]

Rifle brass stretches when it's shot.  Cases for .223 need to be between 1.750 and 1.760 inches.  If they are longer than 1.760", you need to trim your brass.

[HesedTech]

A case gauge for bottle neck rifle is to determine length from the shoulder to the base (where the primer is) and if it will fit in the chamber of the barrel. If the base sticks out then the shoulder needs to be “bumped” down  until the base is flush. You are setting the “head space.” The case OAL is measured after sizing to the proper head space and it it’s too long the case is trimmed.  

 

Good discussion and pictures on this:https://www.ar15.com/forums/armory/Noob-reloader--Headspace-question-and-Headspace-gauge-for-Cartridge-AND-for-Rifle-Chamber/42-479681/

 

However if you don’t have enough over travel on your press to adjust the headspace/shoulder then you need to get a different shell holder to adjust the length. Redding sells a kit for this. https://www.brownells.com/reloading/reloading-dies/shellholders-shellplates/competition-shellholder-sets/?sku=749005614&cnxclid=16779005926716256284010070301008005&utm_term=16779005926716256284010070301008005

 

When you are done reloading it’s a good idea to gauge check the finished rounds so you don’t get them jammed in your chamber. 
 

Have fun reloading for rifle is more detailed than pistol. 

 

[jmac2112]

Thanks for the replies!

 

MadBomber: I do trim my brass, but my question was about headspace.  

 

HesedTech: Thanks for the links.  One of the things I proposed doing was taking some material off my shell holder so that the sizing die would go down further and bump the shoulder a little more.  It sounds like that Redding shell holder set does the same thing but gives you more options.  

 

I guess what I really need is a good way to determine how much headspace I need for my particular chamber.  It may be that my die is doing all it needs to do, and I don't want to size my brass more than it needs to be.  I'm in the middle of watching this video which seems to have some good info on the subject:

 

 

 

[HesedTech]

7 minutes ago, jmac2112 said:

I guess what I really need is a good way to determine how much headspace I need for my particular chamber.

Plunk test just like a pistol.

 

Take the worst gauged finished round and drop it into the chamber. It should easily spin and fall out when inverted. Even push it as hard as you can with your finger, if it still drops out then it's good to go.

 

The gauges used to check head space (I like the JP the best) are (or should be) milled at min SAAMI specs. An actual barrel chamber can vary depending on the manufacture, tool wear and the day of the week. Your ammo has to match the gun. 

 

As I always say, reloading is a hobby by itself. It is also why buying remanufactured ammo can get sketchy and using reliable sources is a must.

[Tom Freeman]

Does the brass fit in your chamber?

 

It is very possible that your gauge and the chamber are not exactly identical.

[jmac2112]

It fits the chamber and everything seems to work fine.  What worries me is that my full length sizing die is not sizing the cases all the way.  The head is sticking up out of my case gauge just a little above where it should be (about .002").  I've adjusted the die as far down as it will go, and I've got "cam over" when I hit the end of the stroke.  It just isn't going to size the cases any further unless I take some metal off either the die or the shell holder (or buy the Redding Competition Shell Holders that HesedTech referenced in his post above). 

 

My understanding is that I should have about .003" headspace for a semi-auto, and my suspicion is that I have only about .001".  This is based not only on what my case gauge is telling me, but I also tried an experiment today.  I took several cases that I had sized with my die and inserted spent primers in them so that the primers were sticking up about .010.  I put each one in my chamber and dropped the bolt on it, and then I measured how far the primers sat above the head.  They were all in the .001-.0015" range.  

 

Anyway, I'm going to take metal off the top of my shell holder little by little until the die will size the cases all the way.  I don't use this shell holder for anything else but sizing cases for the one AR that I own, so I'm not ready to spend a lot of money on the Redding shell holder set.

 

 

[Tom Freeman]

If it fits in your chamber and you dont have to struggle to remove a loaded round, you are fine.

 

Your gauge isnt the exact same as your chamber.

 

Toss your gauge in the trash and go shoot.

[Farmer]

@jmac2112 This is one way to check your headspace on your chamber that’s worked for me with autos, bolts and SS. 
Fully size four or more cases. Load them like you normally would (you don’t need a max load) But load the bullets Long to start with so that they won’t chamber if you can. Keep seating the bullets until they will just fully chamber. You want the bullets seated into the lands if possible or as close as you can get to avoid over stretching your brass at the head. On some autos I’ve had to use heavier/longer  bullets to achieve this. Some will not feed from the mag either and have to be loaded singly. Once you have them loaded take them out and shoot them, you’re not concerned with accuracy, just forming the brass. Take them home knock out the primers without sizing and measure the brass with your headspace gauge and this will be your max or close to it. Subtract 3-4 thousandths and set your die to size to that length or close to it. With an auto it’s always better to be a little looser. If your die is not camming over  once it’s set or firmly touching the shell holder, you may have to get some of the Redding shell holders otherwise you’ll get varying head spacing. Also remember that a tight or non carbide expander ball on the decapper can also pull the shoulder back out so lube the necks or adjust for that. 
Many of those gauges are cut for minimum chambers and can be too tight for an average one. 

Edited March 11, 2023 by Farmer
Spell

[jmac2112]

Farmer,

 

Thanks for that suggestion!  Can you explain this part, though?

23 hours ago, Farmer said:

You want the bullets seated into the lands if possible or as close as you can get to avoid over stretching your brass at the head

 

I'm not sure I follow how that works.  Is it because it keeps the head pressed tight against the breech face?

 

I recently took some brass that was formed by firing in my gun and did all the other steps you suggest, but I didn't try to seat the bullets long on those rounds (I had just crimped at the cannelure and called it good).  In that experiment, the difference between the low "step" in my case gauge and the height of the brass above that point was between .004" and .005".  However, it sounds like you are saying that this might be deceptive due to the case stretching beyond the actual dimensions of my chamber.  

 

[Farmer]

5 hours ago, jmac2112 said:

Farmer,

 

Thanks for that suggestion!  Can you explain this part, though?

 

I'm not sure I follow how that works.  Is it because it keeps the head pressed tight against the breech face?

 

I recently took some brass that was formed by firing in my gun and did all the other steps you suggest, but I didn't try to seat the bullets long on those rounds (I had just crimped at the cannelure and called it good).  In that experiment, the difference between the low "step" in my case gauge and the height of the brass above that point was between .004" and .005".  However, it sounds like you are saying that this might be deceptive due to the case stretching beyond the actual dimensions of my chamber.  

 

Yes it holds the head against the bolt and allows the case to blow out in the shoulder area and not the head area. If the headspace is excessive on say, new brass and the bullet is seated normally the firing pin shoves the case forward into the shoulder. When the round fires it expands, grips the chamber and the case stretches in the head area. This thins the brass (bright ring above extractor groove) and eventually causes head separation.  To stretch the brass beyond your chamber the load would have to be quite excessive in psi. I’m guessing your gauge is probably at the minimum and your chamber might be a little long. As long as you can get them to chamber reliably with normal sizing I’d call it good. I tried messing around with tighter headspace in autos and it turns into a real PITA. In one of your posts you stated that you were worried that your die wasn’t sizing enough. If it wasn’t they wouldn’t fit and your bolt wouldn’t close fully. With 3-5 thousands you’re not too bad. I had a TC bbl that was .013” and that was a nightmare. 

Edited March 12, 2023 by Farmer
Added

[jmac2112]

Farmer,

 

Thank you for that explanation!  That clarifies something that I've never understood before, namely the relation between excessive headspace and head separation.  I was assuming that the pressure from firing a round would simply drive the case back against the bolt, and any stretching or deformation would occur in the shoulder area as it expanded forward.  It had not occurred to me that the firing pin would drive the case forward, and then the outward expansion of the case would hold it in that position.  

 

As far as examining a fired case in order to determine how much the shoulder should be bumped back, I still have some questions:

 

1) First, it seems that it would not matter where the expansion occurs (head vs. shoulder) as long as the case expands to the dimensions of the chamber.  I understand now why excessive headspace is hard on the brass, I'm just saying that I don't understand why it would matter for this purpose whether the brass stretches at the head or the shoulder.  

 

2) I have read several times, and from people who seemed to know what they were talking about, that a case shot in an autoloader can expand beyond the length of the chamber since there is still pressure inside the case as it is being extracted.  You said above that "To stretch the brass beyond your chamber the load would have to be quite excessive in psi," which seems to indicate that this shouldn't be a problem at normal pressure.  In any case, I have an adjustable gas block, and it has occurred to me that I could remove this variable entirely by dialing down the gas until the bolt won't cycle.  Does that sound reasonable?

 

As a side note, I realize that I seem to be overthinking this.  In my defense, I would say first that I am genuinely interested in understanding how and why things work.  More importantly, I am relatively new to rifle reloading, and a novice in any discipline simply doesn't know which specs are guidelines and which ones need to be taken seriously.  I learned that the hard way when I was repairing motorcycle engines in a past life.  The School of Experience collects tuition on a sliding scale, according to one's thoughtlessness....

 

 

 

 

[12glocks]

I want to recall that Lee's presses do not cam over.  Do you have another press that will cam over? If you move your sizing die over to another press, I wonder if that will give you the other thousandth you are looking for.  I have the Dillon power trimmer with an integral die that sizes the case.  I have to cam over the press (650) to make the brass drop in the gauge.  Dillon 223 dies are supposed to be like small base dies also.

[jmac2112]

Hi,

 

I'm currently sizing on a Lee APP (I load on a Dillon XL650), and I'm not sure if it will truly cam over or not.  If I understand correctly, "cam over" means that the die and the shell holder are making as much contact as they possibly can, but the handle keeps moving and the frame or linkage of the press flexes a bit before hitting a hard stop.  My press is set up to do this just a little, even though I've never really understood the benefit of going beyond the point of full contact between the die and shell holder.  Correct me if I've missed the point!

 

Thanks,

 

John

 

[jmac2112]

P.S. It turned out it was about .002" that I was looking for, and I got it by taking .002" off the top of the Lee shell holder.  Now my cases will size until the head is truly flush with the low step in the case gauge.

[Farmer]

The Lee APP doesn’t have the power to cam over like a HD press like a RCBS, Redding, Hornady ect. Even though the shell holder makes contact with the base of the die there’s still some spring between the ram and the holder. You can tighten the die down enough that they won’t cam over but that’s not the point.