What's causing this - brass bulge near base

[scyzer]

I've just gone through resizing a batch of 223 Lapua brass. Only the second firing and I've full length sized using a new die and shellholder combo.

Around 10 of 100 or so pieces have this weird bulge at the base of the brass, at the very end of where the die squeezes the body in.

These pieces also all exhibit some form of less shoulder bump, around 1-3 thou less than the other pieces. I checked the insides using a paperclip and no sign of incipient case head separation that I could feel.

I used a liberal amount of One Shot for lubrication.

All the other brass seems absolutely fine.

Any thoughts of what might be causing this? Die out of spec (which would be weird given the other pieces seem fine)? Insufficient lube (no issues with 'sticking' brass though)? Too hot a load during load development?

Also - should I play it safe and cull this brass?

 

[Dusty Stevens]

Big chamber. You just need a small base die

 

[Edd]

Based on what I can see, I'm going with "too hot a load during load development". It looks like the case web diameter has grown on those cases. Have you measured the diameter difference, below the ring, between the cases with the ring and those without it?

 

[243winxb]

Too hot a load during load development?

This, or there needs to be more of a bevel on the mouth of the FL die.
Standard factory dies.

 

[DaveTooley]

Bulge or ring?
All cases have a bulge to some degree. Thin side expanding more than the thick side seems to be the most logical explanation.
If it's a ring then your die is making full contact around the case head. That's where the sizing die stops doing it's work. Hot loads might have affected those cases in fewer shots expanding the case head as it transitions from solid to thin. My guess is it will appear on the other cases with use.
Just for the hell of it lay a straight edge on the case in several locations and look for a gap under it.

 

[SmokinJoe]

Going to guess that your new dies are Hornady? I have had Hornady FLS too tight for Lapua at that area and leaves that same ring. You might call the die maker and see if they can lap your die a little. BTW, have also seen that on a custom die, especially when I requested that the die be made on the tight side.

 

[Metal God]

Is this the bulge at the extraction grove ?

 

[divingin]

Does the ring prevent chambering? I'd guess it won't.

As mentioned, it's where the die stops when it sizes.

 

[K22]

I've experienced some bulging of cases with various brands of brass only in 223 Rem. Never experienced it with other calibers, i.e., 22 250, 243, 308 etc.

All the loads were well within established limits regarding powder charges. Cases were full sized in RCBS standard die. Cases chamber and extract without issue. No evidence of pressure issues.

I traced my problem to specific rifles. Same loads, same brand of cases, etc. in other rifles never exhibited this condition. Not all the cases were affected for a given rifle - depending on the rifle, anywhere to just a few to several but never all of them.

My rifle smith examined the cases and the chambers of the suspected rifles and told me that in these rifles, the chambers appear to be slightly out of round. He told me if the sized case chambers without issue, then continue to use them. He attributed only some of the cases being affected to possibly differences in the way the case chambered and / or inconsistency in the metallurgy of the brass but he wasn't total sure.

I've loaded and fired the affected cases several times without incident or effect on performance. Not saying you should do that, just saying this has been my experience for my specific situation. I always thoroughly inspect cases each reloading cycle for incipient head separations and other defects. Have encountered no incipient head separations in these cases.

I did try a small base die and it made the condition worse.

 

[PracticalTactical]

My guess is that whoever chambered the rifle had a tail stock that was not centered to the spindle. As a result, you got a fat chamber. It's basically trumpet mouthed.

This is the reason chambering guys often use a floating reamer head. In this case I would assume the reamer was fixed in a ridged holder, but off the axial center.

Chances are the same flaring is evident all the way to the throat. Since the throat is the narrowest part of the reamer, it is more prone to deflection than the body. The throat likely has quite a taper. Not helpful for accuracy.

The other ~~ possible ~~ cause is a series of waay tooo hot loads that caused the chamber to swell. If that's the case, the action would likely be damaged as well.

 

[natdscott]

Big chamber. You just need a small base die

..or a different chamber.

 

[Metal God]

I don't see a bulge at the die ring . It could be an optical elusion but I do see one inside the extraction grove on a couple cases . The thing is , the brass is so thick right there I'm not sure it's possible to bloat a case that low . I'd think a HEAVY bolt lift and maybe cleaning rod assist to get the case out if that was caused by pressure .

I might not be seeing what others are seeing though .

Maybe line up a row of brass using a ruler to be sure they are straight . See if they are all out of square

Pretty good

Not good showing case heads not square to the case body . Note how the cases are leaning one way or the other

 

[RegionRat]

I would advise the following since the issue can be cosmetic but you want to eliminate a safety margin risk.

Check the diameters of the cases you show with the issue, versus ones you don't and see if there is any significant difference. Check for severe out of round with a runout gage if you have one too.

Sacrifice one with the worst showing and section it lengthwise to see if there is any "necking" or thinning inside where you observed the external signs.

If they don't measure significantly different, and you don't find the necking or thinning of the brass to indicate an immanent rupture between the case body to case head blend, then the issue was your dies occasionally scraping up the surface and leaving a beach mark of material where it stops.

If you have never sectioned a case, there are many ways to slice it in half based on what you have available. You would then use a fine grit sandpaper to carefully flatten the cut. The internal pressure chamber should look smooth and not have any fractures or show any thin disruptions.

Most times, I will show a rookie that a good wet tumble with pins will clean up the internal surfaces well enough to just examine with a borescope and they can relax. It helps to demonstrate this with examples of good and bad in hand.

You could even learn to use a thin wire probe to feel for a grove or disruption of that head to body blend but it helps to be taught by someone with examples of good and bad present to demonstrate.

My guess is this is cosmetic, but since this is not likely to be the last time in your life that you see the issue, now is a good time to stop and learn to diagnose and verify what you are seeing.

ETA: http://bulletin.accurateshooter.com...se-head-separation-how-to-detect-the-problem/

 

[4xforfun]

I don't see a bulge at the die ring . It could be an optical elusion but I do see one inside the extraction grove on a couple cases . The thing is , the brass is so thick right there I'm not sure it's possible to bloat a case that low . I'd think a HEAVY bolt lift and maybe cleaning rod assist to get the case out if that was caused by pressure .

I might not be seeing what others are seeing though .

Maybe line up a row of brass using a ruler to be sure they are straight . See if they are all out of square

Pretty good

Not good showing case heads not square to the case body . Note how the cases are leaning one way or the other

Have the primers been removed in these picks?

 

[Murray Brook]

Big chamber. You just need a small base die

Why would you need a small base die for a large chamber. I was under the impression that small base dies were needed for small chambers. Just asking

 

[Dusty Stevens]

Why would you need a small base die for a large chamber. I was under the impression that small base dies were needed for small chambers. Just asking

To put the brass back where it needs to be irregardless of the chamber

 

[M-61]

Type of weapon?

 

[Nick Caprinolo]

Why would you need a small base die for a large chamber. I was under the impression that small base dies were needed for small chambers. Just asking

A small base die means just what it says. It reforms the brass to the base of the die. This is rarely needed for a bolt gun but almost always for a semi auto such as a AR.

 

[Ned Ludd]

I'm guessing you might have some chamber issues, possibly on top of running fairly stout loads. As someone that has run fairly stout loads with 88-95 gr bullets for years in my .223 Rem F-TR rifles, I can tell you that brass life is quite poor, and it's not uncommon to observe anomalies in the brass, although I've never seen anything quite like what you showed above. It actually looks as though the cases have a bulge on one side, or possibly a longitudinal "stretch", in the region from somewhere around the bottom of the webbing, because the expansion did not appear to be uniform. That is what makes me wonder whether you might have a chamber issue, possibly in addition to running stout loads. I have observed expansion within the extractor groove to the extent that cases won't always spin completely around in a shell holder, but I haven't seen anything that would also cause the case head to be out of "square" like yours appear to be. I can't state with any certainty that what you showed above couldn't be caused by a die during the re-sizing process, but that wouldn't be my first guess. It looks more like something caused during firing that wasn't resolved by the re-sizing operation.

I wouldn't spend any time trying to "fix" those pieces of brass. Been there, done that, and wasted significant amounts of time trying to undo damage I had caused to brass without any positive results. I'd toss most of them and move on. However, save a few in case your gunsmith wants to see them. This might also be a situation in which making a chamber casting might be of benefit. I've never had to do that, but it might provide some insight if there is something wrong with your chamber, or some peace of mind if there isn't. Finally, if you have a borescope, you can use it to check the inside of your brass for cracks/potential case head separation. It may be easier to actually visualize any potential issues from the inside with the borescope, as opposed to the paper clip method, which can certainly work, but is not very sensitive and is indirect.

 

[prwhite]

Exposed case heads.