When Small Base Sizing Goes... Strange

[wyrmzr]

I've already posted this question to a FB page, but without much in the way of results.
I'm loading .223 for 2 different firearms; one is my Savage Axis, the other is my home built AR in 5.56.
Ever since I got this AR built, I've noticed that some of my hand loads don't want to feed. I thought I had this problem licked when I went out and got a small base die; however, I've got a batch of brass right now that was run through the SB die a few months ago, then stored in an airtight plastic container. The other day, I loaded up 30 rounds with this brass, and 5 wouldn't feed into this 5.56 chamber. It's like I never ran it through the die in the first place.
I have since re-resized this brass, and it's feeding fine now, but this raises a whole lot of questions, like how does brass decide to expand out when it's just sitting there?
Along with that, I was thinking 5.56 chambers tended to be loose compared to .223 chambers; I'm not going to complain about a working, tight chamber, but these 2 firearms are acting exactly reverse from what I've been told.
For the record, this expansion is with all types of brass. There were 3 brands in the 5 that failed to feed the other day. The brass is trimmed to 1.755 or less, as I was thinking maybe I had a case length issue originally. I've also tried shortening the OAL of the cartridge, seating just past the cannelure, but it's obvious at this point that the brass is catching at the head space, which the SB die is supposed to fix. The barrel is clean, and I've even tested this simply by cycling rounds through without firing, same result.
At this point, I'm resigning myself to running all my reloads through the gun to make sure they chamber and eject properly.
This particular barrel is a stainless bull barrel, a Double Star: http://www.brownells.com/rifle-parts...TO%2b299xzzx99

[Reddirt62]

Did you check them with a case gauge prior to storing them? I have yet to experience a case growing on me in storage. From my experience it usually ends up being a short stroke on my part when it is a shoulder issue.

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[wyrmzr]

I didn't measure prior to storing them, and that is the only thing I can even begin to think of, is a short stroke on the press. Actually, I did have some "assistance" in the way of an 8 year old, but I'm fairly certain I didn't have her size any brass.

[Reddirt62]

When it comes to my AR ammo I check every round in a case gauge due to some mistakes I made when first starting and the subsequent breaking down of 800 rounds......lesson learned!! 😊

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[blikseme300]

Did you check that the brass chambers before loading? The only time I had a similar experience was when during seating I somehow deformed the shoulders and those would not chamber.

Another gotcha can occur if you seat and crimp in one step and the brass is not trimmed exactly the same. Longer brass will typically deform at the shoulder if the setup was done with shorter brass. I prefer a collet die when I crimp rifle loads as these don't exert any force on the shoulder.

[country gent]

Depending on how hard the barrel extension was torqued to bring into time it may have slightly choked the chamber at the back 3/4"-1".Also a lock pin hole drilled deep for the extension may have put a tight spot in the chamber. This will be at the 12:00 spot in the chamber. As to brass like most metals they expand and contract with heat or cold and have a memory, wanting to go back to the at rest form. I would make a chamber cast and measure against the brass that works and what doesn't. Also check the shoulder datum on the sized brass. Small based dies tend to want to push the shoulder forward some due to moving the bodies brass more. Inking a sized case and chambering will show the tight areas. If its in the body of the case then a chamber reamer ran in to lightly clean up the body and not move the shoulder forward may cure it also. SIzing the case then turn and run lube down with fingers and size a second time may get past the memory of the brass.

[wyrmzr]

Depending on how hard the barrel extension was torqued to bring into time it may have slightly choked the chamber at the back 3/4"-1".Also a lock pin hole drilled deep for the extension may have put a tight spot in the chamber. This will be at the 12:00 spot in the chamber. As to brass like most metals they expand and contract with heat or cold and have a memory, wanting to go back to the at rest form. I would make a chamber cast and measure against the brass that works and what doesn't. Also check the shoulder datum on the sized brass. Small based dies tend to want to push the shoulder forward some due to moving the bodies brass more. Inking a sized case and chambering will show the tight areas. If its in the body of the case then a chamber reamer ran in to lightly clean up the body and not move the shoulder forward may cure it also. SIzing the case then turn and run lube down with fingers and size a second time may get past the memory of the brass.

This is basically the solution I've come up with. In this situation, I'm going to do a full length resize with my Lee die, trim if needed, then size again with the RCBS SB die. I shouldn't see a difference in length after the first sizing, but I will measure length again after the SB resize too. From there, I'll just chamber the brass in the barrel before loading.
The only down side here is that if I fire the rounds in my Axis, I'm overworking the brass, but I don't have a shortage of .223 anyway, as I have access to the local LE shooting range, and that provides me with .223/5.56 and .40 in fairly large numbers. One of these days I may have to start selling the stuff; that would offset my powder, bullet, and primer costs...

[Bzcraig]

I have separated my 223 brass to keep the bolt gun brass from being over worked.

[Greg S]

You need to get a cartridge gage, Hornady, RCBS or other an.measure the case on the datum line on the shoulder. I bump my shoulder on 5.56 and 7.62 back .002 and never had a problem with a bolt not locking. General rule is .004 for semi's but if you lube well and periodically check and have a consistant batch of brass it is pretty consistant. Screwing thendie down to the shell holder and another 1/8 or 1/4 turn cannreturn the brass back to factory SAMMI -0.002 TO -0.006. This is working your brass too much, of the six 223 ARs I have (1) is +.002, (1) +.003 (3)+ .004 and one I can remember) Lets take one of my +0.004 chambers. Factory 62gr 5.56 gages at sammi -0.002 to -0.006. I fire it and it comes out +.003/4. I resize it back to factory spec and I'm setting the shoulder back .010. My case length grows fom 1.750 to 1.756-1.759. I fire it a second time and resize it back to the above spec and I'll have to trim it. After 6 reloads I've probably trimmed it 3x so that would meet the .030 rule and time to go into the trashn can.

Do yourself a solid one and get a gage. Both your chambers should be real close o one another so you should be able to bump the shoulder back minimally to fit both yiur bolt and semi.

A few notes though, about the 3rd or 4th firing, that brassnis going to work harden and you probably need to adjust yournsizing die to get the proper bump or anneal the brass. Thhs is really apparent with 7.62 NATO brass. Good full coverage lube is important to consistant resizing. For case lube I use either RCBS on the pad or Redding green goo.

The main difference between 223 and 5.56 is alittle longer in the case mouth and a deeper throat smewhat like a Remington 223 throat. I've always used a standard 223 dies (RCBS and Redding) for loading ammo for my ARs. I've never needed to use a SB FL sizing die.

Also, check your yiur AR. Some are 5.56 (Colt) and some are 223 (old Olympics). If you running 5.56 pressure ammo through a 223 chamber you are running well over 65-70 k which would explain some things. How are you primer pockets holding up? I generally get 4-6 reloads out of a 5.56 before I leave it lay. Greg

[No Blue]

Bottom line is you make a Cerrosafe casting of your chamber and compare that to whatever the dies are churning out. You can do all the rest, but if your brass is .001" longer or bigger, or the shoulder is in the wrong place than the comparable chamber dimension; you'll know.

It takes some smarts and measuring equipment, but that's what being a tool maker and user is all about....

[M-Tecs]

but this raises a whole lot of questions, like how does brass decide to expand out when it's just sitting there?

It doesn't

but it's obvious at this point that the brass is catching at the head space, which the SB die is supposed to fix.

The small base dies are smaller at the base and they effect headspace the same as standard dies. Headspace and base size are not related.


What headspace is.

http://thecmp.org/training-tech/armo...ner/headspace/

[psweigle]

You first off need a cartridge gage. Then you need to answer us what PRESS you are using to reload those 5.56/223 rounds with. I had a good friend have the exact same issue, and it turned out that he didn't have his sizing die adjusted properly in his press.

[M-Tecs]

[wyrmzr]

Interesting; at one point, I'd had head space described to me totally differently. Good to know the actual definition is NOT what I was told.
Basically, I was told head space was from the bolt face to about 3/4 inch. At least, that was what was supposedly the important part of it.

[Bayou52]

I concur that the OP should be using a case headspace gauge to assure the sizing die is properly set and the case shoulder properly placed.

To eliminate the possibility that the crimp ring in the seater die is not pushing the neck down and buckling it, suggest the seater die be raised so it cannot crimp. I often use no crimp at all for 223, and when I do, a Lee FCD eliminates the risk of neck bulging.

[M-Tecs]

Interesting; at one point, I'd had head space described to me totally differently. Good to know the actual definition is NOT what I was told.
Basically, I was told head space was from the bolt face to about 3/4 inch. At least, that was what was supposedly the important part of it.

For checking headspace the RCBS precision mic is outstanding http://www.sinclairintl.com/reloadin...prod33476.aspx

The Hornady is more versatile http://www.hornady.com/store/Lock-N-...h-Body-1-Each/ but unless you have a actual headspace gauge it doesn't give you an actual measurement.

http://www.brownells.com/gunsmith-to...prod19183.aspx

[wyrmzr]

I did check headspace, got gages for the .223 when I built the AR, and went ahead and checked the Axis as well. Both are fine according to the go/no go gages.
A few thousandths is apparently what I'm seeing for difference between chambers, but that's all it takes. So, time to sort brass between the two rifles. I'm not as much worried about number of reloads per case as some, as I happen to be lucky enough to have access to the local LEO ranges, and there's no shortage of 5.56/.223 brass, as well as .40.
But, the bolt action obviously doesn't need all the work put into the brass anyway; neck sizing and trimming and it behaves itself just fine. The AR just happens to get fed more ammo during the typical outing, so if I set 1/4 of my brass aside for the bolt action, I'll have plenty.

[psweigle]

You aren't by chance sizing them on a lee turret or progressive press are you? If so, the die holding turret can sometimes move under sizing and cause your issue.

[wyrmzr]

No, this is a single stage press. I'm starting to think that someone (aka my "help") managed to throw a bunch of brass into the wrong container.
So far, I'm not having issues so long as I use the SB die myself. Unfortunately, for a while, my reloading equipment was at another guy's shop, and his grandkids had access to it when I wasn't there. This may be the solution to the mystery. This makes me glad I moved my reloading equipment to my apartment.

[EDG]

If you have ammo that is not working and you have not been thoroughly checking it in process and you have had someone around your reloading that you have not monitored 100% you need to realize that your process is not under control. You cannot put your brain into neutral while reloading.
Make no assumptions that you did anything right. Check your work. You are working with energetic materials and it is not very forgiving. You have been doing the reloading equivalent of backing out of the driveway without looking first.

No, this is a single stage press. I'm starting to think that someone (aka my "help") managed to throw a bunch of brass into the wrong container.
So far, I'm not having issues so long as I use the SB die myself. Unfortunately, for a while, my reloading equipment was at another guy's shop, and his grandkids had access to it when I wasn't there. This may be the solution to the mystery. This makes me glad I moved my reloading equipment to my apartment.