Interesting pictures of rim splits

I have been cleaning out my garage of an awesome amount of fired brass I have accumulated over the years. I ran across a bag of .30-30 brass, maybe 50 or so, source unknown, which all demonstrated identical rim splits:

Note that all splits are in exactly the same location, at the P. Also, all of the “Ps” are slightly blackened as shown. Must have been something about the metal stresses set up by the headstamp bunter at that location which caused failure upon firing.

Pretty hard to damage a case that close to the rim and have it split from interior pressure.

Given the location, uniformity of the split on the rim, and coloration, and the absence of signs of high pressure on the primer, I think this is a deliberate cut made in the rim by a reloader, perhaps to ensure that the case are oriented the same way in the chamber for accuracy, or to denote cases with a specific load he was trying.

I do not think it is an actual case failure.

I have no idea how one would create those splits even if he wanted to. They are definitely cracks through the metal, not just markings, such as from a Magic Marker, etc., nor cuts. And who would worry about case orientation in anything chambered in .30-30? I don’t believe I have ever seen or heard of a bench rest rifle chambered in .30-30. Anyway, they all went into the recycle bin. I wouldn’t trust using them.

Splits in cases are caused by two sources…Internal Pressures from Firing, and “Bad brass” (ie, brass with rolled included impurities, etc), or Die Problems in drawing.

The Position of this particular “crack” seems to indicate a problem with the “Heading Bunter” which forms the Rim and flat head from a 3rd.Draw, before headstamping and Primer Pocket indentation.

How many of your cases show this defect?

Normal QA in an ammo factory should have picked up a recurring defect such as this on normal station cases inspection ( between one process and another).

Doc AV

“How many of your cases show this defect?”

I had a baggie with about 50 of them, and every one demonstrated the identical failure and location. They probably all came from the same lot, as headstamps are all the same, so I would say it is a lot defect. The cracks were blackened, so I suspect there was some high pressure gas leakage. As I said, I have no idea where they came from, as they were just a part of my brass accumulation. Someone probably gave them to me. I did not originally fire them. I kept the three examples shown, all the others went out in the recycle bin. I have never seen anything like this.

my money’s on the head-stamp bunter. Precisely in line with the “P” on each case. A defect in the bolt face of any type rifle would cause random placing of the ‘crack/cut’. It would be a most unusual place for a pressure crack or a brass ‘defect’ which would be a totally random occurrence also. Even a bench rest shooter marking his case to indicate number of times fired or to orient the case would not be this precise…bunter. my .02 cents worth.

I think, that a reloader used a triangle file to mark the cases, for what ever reason. The " splits " are too uniform to be pressure splits.
If you look closely at the rim, you will see how the " split " is v shaped & all are the same size ! M. Rea


Never say never.

The 30-30 is a very accurate cartridge when chambered in a good barrel in a well bedded action. In the 90s, there were Benchrest 30-30s and also some wildcat Benchrest cartridges using the 30-30 case, such as the 30 Aardvark. The 30 American brass was especially made by Federal to be formed into wildcat competition cartridges.

I’m not saying that your split cases had anything to do with Benchrest. I’m just saying.

The only things inherently inaccurate about the 30-30 are the rifle itself and poor quality brass. Indexing the cases is one way to partially correct the brass problem. IMHO, those cases were marked by the owner. I agree with mdrea.


Brass is a funny alloy, the stresses set up in the multiple forming processes are unfathomable and can appear decades later. Saying that I have never seen a rim split.

The tally mark theory is a possibility, It used to be quite a common practice over here. Either to keep a record of how many times it had been reloaded or (mainly in pistol cases) to identify ownership on ranges.

It could also be a chamber aligning mark as mentioned before, if somebody has been reading the right books, but if that were true I would expect a number written in marker pen on the body of the case as well (?)

We are all thinking in terms of a lever action rifle but wasn’t this calibre used by some of the long range single shot pistol tyros which might make some of the theories more plausible?

Here’s a photo of a rim split. This one is especially bad, going all the way up the side of the case.

Quite different from the 30-30 case rims that are shown.


Marking the case for orientation in the chamber is one way to overcome bullet runout caused by a lack of uniformity in brass thickness at the case mouth. Another way, of course, is outside neck turning to equal thickness. Some single-shot rifle shooters do both. I don’t know his system, but Harry Pope, certainly one of the great shooters in history, often used a single cartridge case, reloading it for each shot at the shooting bench, when shooting groups with single-shot rifles. He also had a system, probably some sort of marking of the cartridge head, to precisely load the case in the chamber with identical orientation each time. I go along with Ray and Rea.

I am also happy for Ray’s comments on the potential accuracy of the .30-30 cartridge when fired in bolt action or good single-shot rifles. I have said that for years, but with the words usually falling on deaf ears. Occasionally, you even find a lever gun that for one reason or another, shoots exceptionally well in this caliber.

Ray - am I right that your cracked-rim (and head) example is probably a ballon-head case?

John: Note that while Harry Pope did often make use of a single cartridge case in his match shooting the bullet was seated into the rifle by a false muzzle, so the case had no influence one way or the other in bullet runout. Jack

The case that I showed is a 45-70-500, tinned, headstamped F-1-97. It’s an unfired original. The split sarts at the base on one side of the primer and extends to the edge of the rim and partially up the side. I’d have to pull the bullet to see if the split starts at the flash hole, something I do not want to do. You occasionally find similar cracked heads on modern cases, usually the result of faulty case head anneal.

John - In the parlance of those days, the case was called a “solid head”. But, as you said, today we refer to it as a balloon head.

Jack - While it’s true that Harry Pope loaded the bullet seperate from the case, some Benchrest shooters in the early years of the competition, did use one case, with the bullet seated in the conventional manner. Shortened time limits for firing a target, plus improvements in the quality of new cases, combined to make this unusual method of loading obsolete. But, it’s still common for Benchrest shooters to make only a very few identical cases for each barrel and re-load them at the bench between targets. 20 to 25 cases can last an entire season if treated carefully. Some shooters will have 5 or 10 favorite cases that they mark and use for each record target, leaving the others for sighters, fouling shots, etc.


If anyone has the metallurgical equipment, skills, and a desire to investigate the splits further, I’ll be happy to send him one (or all 3) of the pictured .30-30 cases I kept. Just PM me.

The Split which penetrates the Head and Body of case is commonly known as a “K” Split. It is due to bad Cupping of the Brass (First stage process…Punch and cup from sheet.)

Will cause catastrophic case failure if fired ( with Possible rupture of Bolt and receiver walls as well.)

Low case splits are a sign of Bad Case Punch design (too tight a radius to form the inside of the Cup) and as a result, stresses are set up which will eventually form a crack ( Age or Season Cracking.)

Annealing the Head is not a solution, as the Head has to be hard anyway… Such splits are usually seen on “Folded Heads or Balloon head cases”, but in the right (?wrong?) conditions, can also show in solid Head cases.

Other reasons for the split are Bad sheet orientation when Milling, Impurities “streamed out” when Rolling the Brass, out of round drawing of the Cup, etc.

Kynoch had a problem in the Early 1950s with “Keyhole” blow-outs in .30/06 at the Web-Body junction…It was found that the internal radius of the Draw Punch was too tight, and actually “cut” into the case body inside…forming a stress Point, which then “Blew Out” on firing. ( 1952 or 1953 Lots…The Problem was rectified by enlarging the radius of the Draw Punch…)

Doc AV