What’s wrong with my .308 brass?

[Notalentbum]

I started to process some of my .308 brass this past week. I’m using same full length sizing die I always have. But now hardly any will go into my case gage to depth. They are all stopping short of full depth anywhere from .030-.125 and the won’t chamber in my bolt gun. I went as far as buying a new die set just to be sure I hadn’t damaged my sizing die somehow.
After the new die failed to fix the problem I started looking deeper. I used a Sharpie to color a case and dropped it in my case gage. I pushed it with a bit of finger pressure and then knocked it out of the gage. You can see in the picture it’s hitting just ahead of the base of the case. My dies won’t reach down that far to reform that part of the case. My sizing die is set to where it is just hitting the shell holder. I don’t think it is pushing back the neck of the case. At least the few I checker aren’t pushed back.
Why are these cases bulged that far back and how can I fix them? I know I fired the majority of them from my AR-10. Is it possible that the chamber in my AR-10 is not properly supporting the case that far back? Are all these cases now junk?

Thanks, Matt

 

[BGDave]

First thing I would do is the bent paper clip check to see if the ring is on the inside too. (Impending case head separation). Assuming these are once fired cases, I would also find some headspace gauges. You may have a long chamber in your rifle.

Edit to add; I also notice another bright ring at the base of the shoulder. Something is off with your rifle.

 

[turnerdye1]

Get a set of Hornady comparators also. Checked the shoulder measurement after firing. And see if you’re bumping the shoulder back far enough

 

[shibumiseeker]

How many times have these been fired? How does a new factory round seat in your barrel? What is your OAL for the brass?

Off the cuff without more data, it looks like your AR-10 may have an exceptionally loose barrel. I have a few ideas but without the above I’d just be spitballing.

 

[Robert Richardson]

Try turning your sizing die about another quarter turn down.

 

[Notalentbum]

Try turning your sizing die about another quarter turn down.

It’s already bottoming on the shell holder.

 

[Bill2905]

It’s already bottoming on the shell holder.

Most full length sizing dies come with setup instructions that direct the user to screw in the die an additional 1/4 to 1/2 turn after it contacts the shell holder. This takes out any excess play in the press linkage and will provide more setback. I have had instances where after doing this, I still had to set the die a little deeper to get the desired shoulder setback. Try this on a few of those cases and see if it makes a difference. You should use some type of comparator to measure the shoulder datum line before and after sizing the case.

 

[Hawkeye7br]

I suspect your AR10 has an oversized chamber. These cases will probably be ok in that gun but not in others. Buy some new brass or factory ammo for the bolt gun and keep it separate.

 

[2in1evtime]

Check your base dimensions against the dimension just below the shoulder that will tell you if the base is bulged, I have gotten into brass that had excessive shoulder that needed bumped back, all was fired from semiautomatic and machine-gun, i keep all my bolt action brass separated by gun, and all semiautomatic separated in bulk. I had a ar10 that had a slightly oversized chamber and the brass gave me fits but i don't own or plan to own any other ar10's.

 

[JeepHammer]

Drop a case (that fits) into your chamber and use a flashlight to see how much of that case is UNSUPPORTED...

All ARs are this way, and plenty of other rifles too...

Besides that,
Take a look at the radius (funnel) taper in your dies,
It doesn't take long to figure out why the die isn't pushing the lower case boating back in where it belongs...
.....

There is something called a 'Small Base' die.
It has a little less taper/more contact with case.
The draw back is they usually press the UPPER case sides in too far to try and drag the lower case in a little.

....

The 'Proper' (most direct) way to push that lower case back where it belongs is rolling the case between die plates that will roll/push the LOWER sides back in where they belong.

See Case Pro 100 die plate roller machine.
NOT CHEAP!

Case-Pro 100

www.casepro100.com

A Case Pro, and properly machined die plates roll that lower case bloating back where it belongs, straightens the rim, trims rim burrs, and generally reconditions the lower end of the case prepping it for further case conditioning and proper resizing.

I use a case roller on all my rifle brass, being a fan of PROPERLY sized ammo that is SAAMI correct for any firearm.

Left is a case qualifier, rejects most case issues,
Center is a case roller, with exception of primer pocket it reconditions the entire lower case,
Right is an upper case sizer & trimmer using common top down dies.



Now, I can tell you unless you are going into competition that a failure means you loose, or you life depends on the rounds you make,
OR, in my case, I do cases for people & firearms I don't have anything to do with,
These MUST be SAMMI specification,

The cost for the random home reloader isn't worth it...

Let me say that again,
With only a few exceptions, this isn't worth the money to buy, set up & maintain.
The guy that only loads a few hundred, or a few thousand a year is NEVER going to break even on cost.

There is nearly $10,000 in that picture, so it's going to take a crap load of brass to break even.

 

[JeepHammer]

I suspect your AR10 has an oversized chamber. These cases will probably be ok in that gun but not in others. Buy some new brass or factory ammo for the bolt gun and keep it separate.

Um...
All semi-automatics have 'Oversize Chambers', it's a requirement to feed at the speed autoloaders cycle.

All ARs have unsupported lower cases.
Most semi-autos have unsupported lower cases.
Again it's the nature of the beast.

The ONLY serious issue is potential for case head separation.
The more the case swells, the thinner the case gets at the swell.

Bloating is pushed back in, it travels up the case and is eventually trimmed off.
This doesn't mean the case doesn't thin every time...
The same way the primer pocket loosens up a little every time it's reloaded.

 

[Bill2905]

Going forward, you might want to consider keeping your bolt rifle brass separate from the AR-10 brass. I would do that if I were reloading the same cartridge for both an AR style rifle and a precision bolt rifle.

 

[55fairlane]

My best guess, with using a set of go/no/field to check headspace, is A) your sizing die isn't set deap enough & lack of lubricating when sizing.
How many firings are on these cases?

 

[Notalentbum]

My best guess, with using a set of go/no/field to check headspace, is A) your sizing die isn't set deap enough & lack of lubricating when sizing.
How many firings are on these cases?

I can’t set the sizing die any deeper, it’s hitting the shell holder fairly solid. I haven’t had a chance to see if these will go in the chamber of my AR but they definitely won’t fit my Savage bolt gun. At most these have been fired 3 times.

 

[55fairlane]

What dies? What press?

 

[Onebad06vtx]

Thats why they make Small base sizing dies.
Simple fix though.
Take about a file to the bottom of the sizing die.
I would use a lathe to do it but a file would work.
You could also take some off the top of the shell holder.
Or just keep your brass seperated.

 

[Leadeye]

I can say that I've had good luck with small base size dies when running brass from an M60.

 

[2in1evtime]

I can’t set the sizing die any deeper, it’s hitting the shell holder fairly solid. I haven’t had a chance to see if these will go in the chamber of my AR but they definitely won’t fit my Savage bolt gun. At most these have been fired 3 times.

Redding makes a set of shell holders that gives you a little more push into the sizing die i mainly use them for shoulder set back myself

 

[edwea]

Just a thought...neck sizing die instead of full resizing die? I know I mostly just size the neck on my 308 brass, except for when I get brass from others, which gets the full length resize. It would be easy to get them confused.

 

[Notalentbum]

Lyman Crusher II, I have tried Dillon, Lee and RCBS full length sizing dies.
I’m going to try to get back at it tomorrow. I got the part for my tumbler today and just started cleaning cases while assisting the wife with Christmas decorations.

Matt