An FC .308 Win case oddity .... what the heck happened to these cases?

[MCMXI]

About 12 years ago, a friend gave me 200 FC .308 cases (all from the same lot) left over from factory ammunition that he'd fired once only (still had the original spent primer in each case). IIRC he had at least a couple of semi-autos at the time but I don't know which rifle(s) he used. I know he had an HK and a Saiga I think, and possibly an FAL. I just bought a POF in .308 and have begun putting together some loads for it so I figured this would be a good time to make use of the FC brass. Last night I went through the usual routine of tumbling and then sorting the cases to throw out any with obvious defects. During the FL resizing step I noticed that quite a few of the cases have a ring just below the shoulder. Those cases are significantly easier to resize but upon further inspection, many of those "ringed" cases have tiny cracks on the shoulder. So now to my question .... what the heck happened to these cases? Were they fired in a poorly cut chamber or is there a particular semi-auto out there that is well known to ruin cases in this manner?

Normal FC cases from the same lot prior to resizing ...

Ringed cases from the same lot prior to resizing ...

Ringed cases after FL sizing ...

Thanks.

 

[USSR]

1858,

Have never seen anything like that before. But, I'll take a SWAG. The guy used them in a .30-06 rifle with one of those inserts in the chamber that allow you to shoot .308 in them.

Don

 

[MCMXI]

Don, it's been a long time and I'm not sure what rifles he had back then so you could well be right. I've lost touch with him over the years so there's really no way to confirm either way. I'm hoping that someone has seen this before and knows what caused it. I'm in the middle of sorting out all the "ringed" and non ringed cases. I don't feel comfortable with the idea of using the "ringed" cases even if I can't see any cracks on the shoulder or neck. The O.D. of the case below the ring is larger by about 0.005" i.e. the case steps down 0.005" to the shoulder.

 

[Walkalong]

I haven't seen anything like that either, but Dons guess sounds plausible.

 

[MCMXI]

I haven't seen anything like that either, but Dons guess sounds plausible.

I've been reloading since '92 but I never stop learning. That's one of the great things about this hobby, it never gets old, and just when you get comfortable, something like this crops up.

So would the .30-06 to .308 insert result in a smaller case size at the shoulder? I would think that it would require a lot of effort to close the bolt (semi-auto or manual) since the case would need to be swaged down. Why would swaging result in cracks on the shoulder?

 

[Martyk]

Holy Moley - the coveted .308R cartridge.. I thought it was extinct Just a guess but if you could ever find the gun they were shot from, it may be an imprint from the chamber.

 

[USSR]

I bought one of those inserts from an outfit out in Idaho many years ago. They are supposed to make up the difference between the shoulder of the .308 case and the shoulder portion of the .30-06 chamber. After you fire one .308 cartridge, the insert is supposed to expand and remain in the chamber. I could not fully chamber a .308 cartridge using the insert with several .30-06's I had, so I sent it back. Chalk it up to one of those great sounding ideas that didn't pan out.

Don

 

[qajaq59]

I haven't a clue what did it. But I don't think I'd shoot them.

 

[Bart B.]

Don (USSR) may have nailed the reason. Having seen dozens of 7.62 NATO rounds fired in 30 caliber M1's ( poor souls thought they had 7.62 converted ones at local Navy rifle matches), some of them had a similar ring on them. Those inserts were made at the USN Small Arms Match Conditioning Unit at San Diego in the early 1960's. The only time they worked reliably was when the chamber was tight enough to require those inserts to be driven into the barrel with a mallet smacking 'em very hard. Otherwise, they often shot out; especially from chambers at the large shoulder/neck diameter end of specs.

The thumbnail picture below's "original" half shows your fired case as you got it with the ring barely visible (red arrow) a few thousandths below the body-shoulder junction. If the insert doesn't have a fine-edge fit between it and the chamber but instead a tiny step, that step will be pressed into the case when its fired.

In the "sized" picture of the case, your full length sizing die probably reduced the body-shoulder junction's diameter pushing the shoulder forward. This made the ring appear further below that point as can be seen by the picture. It's more visible here because there's more body in front of it.

At least this is my guess as to what happened.

 

[MCMXI]

In the "sized" picture of the case, your full length sizing die probably reduced the body-shoulder junction's diameter pushing the shoulder forward. This made the ring appear further below that point as can be seen by the picture. It's more visible here because there's more body in front of it.

Bart, here's a photo comparing the same "ringed" case before and after sizing so I'm confused by your post above. Note that the camera angle isn't quite the same.

The three photos in my original post show (from top to bottom) five cases that initially didn't appear to have a significant ring, five cases that clearly have a significant ring, and the same five "ringed" cases (not in the same order ) after FL sizing. I think you're comparing a case from the first photo to a case from the third photo.

Upon further inspection, three of the five cases in the first picture also have a slight ring but in a different position on the case (see photo below). The ring is no where near as obvious but it's there just below the shoulder. If a chamber insert caused this, then I'd have to assume that there were two different chamber inserts in two different rifles.

As for shooting the "ringed" cases ... I'm off to the range today with some of those cases loaded up to see if fire forming will iron out the ring.

 

[MCMXI]

I used some of the "ringed" cases today without incident and it looks like they did fire form a little. Regardless, that FC brass is going to be used for my SHTF loads since it really is crappy brass. I suppose I'll have to buy some .308 brass now (I was told that Winchester is good for semi-autos). I'm sure as hell not gonna use my Lapua brass in the POF. Anyway, best group from the FC loads today was just over 1 MOA at 100 yards prone with a bipod. Not great but not bad for a new rifle (AR-10) and it'll get a whole lot better once I work up a load for it.

 

[Bart B.]

1858, I may have mixed up case pictures for my example. I agree with your reasoning that more than one inserted rifle was used.