Was reading Hatcher's Notebook...

[AbitNutz]

I was reading Hatcher's Notebook about action and cartridge strength. Hatcher states that rimmed cartridges were stronger than rimless because that the case head was completely supported around its circumference. The problem is the area of the cartridge that is exposed and unsupported due to the extractor/groove radius.

It's true that the extractor groove radius does "leave some part of the actual cartridge case wall hanging out in the air". That's a direct quote from the book. He further states: "a rimmed case does not have this weakness. The case enters right up to the rim and there is little chance for the cartridge to fail at the head".

Hatcher said the reason a weak action (compared to Mauser's and the like) survived without blowing up was because it used a rimmed cartridge. This sounds like action strength and cartridge strength are being confused but there's a lot more to the chapter that better explains it.

The context of this was in relation to extreme over pressure scenarios. He used proof loads of 75,000 psi and some up to 120,000!

It's true, that today we don't seem to have any problems with rimless rifle cases blowing out. If you were to build a bolt action rifle for ultimate strength...wouldn't you build it for a rimmed cartridge? Forget any feeding issues. Maybe you use a Mannlicher rotary magazine to deal with this.

Assuming we are only dealing with bolt actions....It seems that a rimmed case, with a fully recessed bolt face that completely surrounds the rim, would make the strongest possible combination. Do you folks agree with this?

[tazman]

You still have to have a spot open for the extractor to grip the rim and pull the cartridge out. That spot would be unsupported by your design even on a rimmed cartridge.
In actual use, the extractor in many modern actions(think Weatherby mark V ) forms a portion of the bolt that surrounds and encloses the case head since it is also inside the action/barrel when locked up thereby not leaving a weak spot to blow out the case head.

[AbitNutz]

I think what Hatcher was talking about was the shoulder in front of the extractor groove. That portion of the case will be unsupported no matter how the rim itself is surrounded....no? On a true rimmed cartridge, there's no shoulder/indent at all. Clearly, it's not really much of a threat but if a case is going to fail, it has little choice but to fail there. It is true though that the extractor cut is an an avenue weakness, even on a rimmed case.

[Victor N TN]

Something you might take into consideration. Rimmed cartridge cases won't reload as many times as the rimless cases.

I'm NOT sure why. But I've read it in several different publications.

Do you know any rimmed cartridges that will shoot as accurate as a 30-06, 308, 222 or 6PPC? When it comes to accuracy, the geometry of the powder column as well as the projectile, powder and primer are something that makes a difference in accuracy.

[Der Gebirgsjager]

You might partially answer your question/theory by examining the bolt faces of the 1891 Mosin-Nagant, 1888 German Commission Rifle, and the 1895 Steyr-Mannlicher rifle. A rimmed cartridge head can be fully enclosed within a recessed bolt face by using an extractor that is part of the rim of the bolt face and which snaps over the cartridge rim upon closing. In practice such extractors were found to be less durable than the rotating claw extractor of the 1898 Mauser and to offer less positive extraction under dirty (combat) conditions. While the other benefits that you talk about are obvious to one who studies the designs, the rimmed cartridge was left behind because of the better adaptability of rimless cartridge cases to fully automatic weapons. Rifles then followed suite so as to be able to utilize the same ammunition. From military rifles using rimless cartridges that were sporterized the use of rimless ammunition spread to newly manufactured sporters. As the metallurgy and manufacturing of ammunition improved cartridge case head failure at normal pressures became just about a non-issue. So I believe that your supposition about rimmed cartridge cases contained in a proper chamber as potentially being the strongest is correct, there remains little practical difference.

[yovinny]

Even IF the brass is better, and thats a big IF, I dont think the action/chambering for rimmed cartridges in a bolt action is as good.
Rimmed in a bolt usually run with greater head space. Maybe not in theory, but have you ever measured some rimmed cartridges ? It's been years since I did, but I dont remember any that werent undersized and the rifles head spacing is usually well on the generous side of tolerance.
Combine both factors and bolt actions with rimmed cartridges sure wouldent be my top choice for pushing the pressure envelope....

Now a custom put together tight on some specific brass would be another cup of tea,,But a standard chambered rifle and standard brass,,,not so much.

Just my .02,,,YMMV

Cheers, YV

[runfiverun]

my savage 12 in 220 swift would be a pretty stout argument to almost all of the above.
so would the 225 Winchester in a model 70.
anyway you'd at least be comparing apples to apples in the pressure and accuracy department.

[shooter93]

Read Ordinance Went Up Front by Dunlap and you'll get some eye openers on the subject of action strength. They tested them all and some of the results will surprise you.

[Mk42gunner]

One thing you have to keep in mind is that balloon head cases were very common in Hatcher's day, now they are an oddity. Whether that would make any difference in his opinion, I cannot say.

Robert

[AbitNutz]

Hatcher was specifically addressing bolt action rifles and cartridges of more or less, the first world war era, like the Mauser, Springfield, Enfield, Mosin, Arisaka and Krag. While it is true that there were balloon head cartridges in that era, they were never in 30-06, 8x57, 30-40, 303 British, 6.5, 7.62x54r and 7.7 Japanese.

He was testing rifles with 75,000 to 120,000 psi "Blue pills" as the proof loads were called and he was talking about case/action strength in that context....at least that's how I read the information in his book.

[blackthorn]

Quote "Something you might take into consideration. Rimmed cartridge cases won't reload as many times as the rimless cases.

I'm NOT sure why. But I've read it in several different publications."

Because rimmed (and belted) cases do not depend on head spacing off a datum on the shoulder, manufacturers are not too careful when machining the chambers. This practise often results in chambers that are what can only be described as "sloppy". If you successfully fire-form your rimmed cases and then neck or partial size only after that, case life is extended significantly.

[lotech]

What blackthorn mentions about sloppy chambers is true. I've seen this in several .30-40 Krag chambers. Neck and shoulder area will vary enough to eyeball the difference; no measuring necessary.

[lightman]

Hatcher makes for some interesting reading. I like the experiments that he did with exploding cartridges like you would have in a house fire.

[Ballistics in Scotland]

I think the strength of rimmed heads is superior (though some deny it) for two reasons. Reason one is that if you set a Mauser or Mannlicher extractor against a rimmed head, the case wall can run almost up to the tip of the extractor, leaving a triangle of empty space which, in a well set-up rifle can be filled with barrel steel constituting the chamber wall. just have to file that groove so that it doesn't contact the extractor. With the rimless case that chamber wall must end at the front of the extractor groove. Reason two is that there is simply less brass in the cartridge head.

The difference isn't great in practice. The danger of case rupture was greatest when most cases available were of military manufacture, often under war emergency conditions. Modern product liability law can be extremely helpful. Also it sometimes occurred with Springfield rifles which left the case unsupported a little forward of the extractor groove.

[fredj338]

Well Hatcher may have been a brilliant guy, but the headspace issue of rimmed cases allows more case stretch, just fact. I have never had a head sep with a rimless/bottleneck case, but have had several near head sep with rimmed cases @ high pressure. Since most timed cartridges run lower pressures than rimless/bottleneck designs, I would expect more case head issues.

[Blackwater]

There's much in all the posts above, but today, there really isn't a significant difference, because the setup and tolerances of the rifles, the materials they're built with, and the care with which they're maintained, and the loads that they're fed, vary MUCH more than the tiny difference (if any, really?) between rimmed and rimless or belted ctgs. The kind of pressures it might make a difference, and then only to an experimenter for whatever heady reasons he found to do it, would be destructive tests, and I have great doubt whether that would reveal a difference even then, at least surely not anything of significance. Having blown up a gun once myself, I can attest to the fact that it's not a very fun pursuit, and gets costly rather quickly.

Rimless functions better in bolt actions, particularly in box magazines, and falling block single shots and most leverguns may work better and more positively with rimmed ctgs. That's much more of a factor than how much pressure brass of each type will take today.