300 win mag cases

[Toddco]

So, i am using some nosler brass for my 300 win mag. Some of the brass is starting to show signs of separation near the belt line. Just wondering if annealing the bottom of the case might "soften" the brass and add a little more life to them, or, am i just asking for trouble by trying to extend the life of them?

Thanks, Toddco

[44 AMP]

Annealing softens the brass. Its used on the neck/shoulder of cases, to delay work hardening and cracking there.

You do NOT want to soften the head of a case. BAD IDEA!

And, I don't think it would work, for what you want, anyway.

Cases cracking just above the base (case head separation) happens because the brass gets thin in that area. It gets thin because of the way firing pressure acts on the case, stretching it. Resizing does not restore the case to original thickness.

Annealing the case "bottom"?? Making a thin spot softer???
I don't think that is a good idea, at all.

moving to Handloading forum

[bacardisteve]

I'd scrap it annealing is to help soften the brass from work hardening. What you have sounds like the a common issue when full length sizing belted mag cases they form that spot above the belt. Years ago I learned with belted mag brass to only necksize untill the brass would no longer chamber. Then I just bump the shoulder back .002 after every firing from that point on. The brass lasts a lot longer the downside is that piece of brass is now sized for that specific chamber and likely won't fit any other.

[Unclenick]

Case heads are intentionally made harder (raises the tensile strength of the brass) than the rest of the case. Softening heads is asking for a head blow-out. The breech of a rifle doesn't make a hermetic seal, so the thinner brass forward of the web expands to seal the chamber, while the harder head prevents pressure from escaping through the gaps between the breech and chamber. The danger of that blowing out, which generally destroys the stock, the magazine, and the trigger group and has injured shooters, is why the heads must be left hard. That they must be left hard is why we don't anneal cases in an oven. You can't let the whole case get soft and still be safe.

Try Bacardisteve's suggested loading method. That will make your cases last a good deal longer.

[Sevens]

Please help me a little bit here. It’s possible that I’m reducing a somewhat complex discussion to an all too simplistic conclusion but hang with me for one second.

Is it a safe and accurate statement if I say that the entire idea behind the old school belted cartridge case was a lousy idea… or at the very least, it’s most definitely a lousy idea today and going forward?

(yes of course, I certainly understand that if you have a much loved rifle and it is chambered for a cartridge that is a belted cartridge, you are where you are, etc)

No new cartridges have been released making use of this antiquated design with a belt have they? Outside of the marketing hype associated with the big obvious belt, was there ever a good technical reason for this belt?

I too have loaded .300 Win Mag and I too have noticed how short the brass life is, and all the frustration is around that belt and incipient case head separation.

Apologies if anyone thinks my post derails this discussion but I’ve wondered this for many years now.

[44 AMP]

Some backstory is needed to understand the belt. Most of the info is in the loading manuals but its usually given in bits and pieces under the individual cartridges. Here's a summary,

In 1912 Holland & Holland introduced the .375 H&H Magnum. It is a long, tapered case with a fairly small shoulder. They added the belt for reliable headspacing in bolt guns and double rifles. H&H also made a rimmed version (Flanged in British terms) without a belt specifically for use in double rifles.

Along with the belt, H&H also introduced to shooting the term "Magnum", which was taken from the wine industry, and indicated a larger that standard size bottle.

In 1925 they introduced the .300 H&H which is even more tapered with a long shallow sloping shoulder. Based off the .375 case it also had a belt, for the same reasons.

The shooting public came to very strongly identify the belted case with high end performance, and virtually demanded it for decades, even though the belt itself had nothing to do with cartridge performance, it was the acceptable style and people passed up non-belted cases for belted ones.

The magnum rifle rounds from Winchester, Remington and a few others, designed in the 50s 60s, 70s all used the H&H headsize and belt. Its what the buying public wanted and expected in those days.

The magnum rifle rounds of the next generation (ultra mag, and the various short magnums) were based of a different, non belted case, not the .375 H&H, and so, don't have the belt.

The belt essentially acts like a rim, for headspacing purposes, without the issue of rimlock a larger projecting rim can cause.

Its not the best system possible for extended case life, but it works, and is totally adequate for the non reloader.

Many reloaders adjust their sizing so the belted magnum case headspaces on the case shoulder, and not the belt. Done right, this extends case life, but it is the nature of bottle neck cases to eventually get thin just in front of the solid case head, and eventually crack there. They don't last forever.

[Paul B.]

OP, first thing I suggest is get a fresh box of ammo and shoot it in your rifle. Then I suggest you set up your full length sizing die using the following instructions.


This is how I set up my sizing die for bottleneck cartridges.

1. Take a once fired factory round and blacken the neck and shoulders with a Magic Marker or Sharpee pen. Some people like to smoke the neck and shoulder, but I find the Magic Marker/Sharpee pen a bit better.

2. Carefully lubricate the case.

3. Loosen the lock ring on the sizing die and back off about two turns from when the die is set to touch the shell holder.

4. Size the case. Note where the marks are on the case and turn the die down about a half a turn and size again. Turn down some more, and resize again. What you are looking for is the marks on the blackening just touching the shoulder.

5. Clean the lube from the case and try it in the rifle. It may chamber just a bit on the snug side. If so, turn the die down ever so slightly, lube and size again. Wipe off the lube and try in the rifle. If it slides in as easily as a factory round, you should be good to go. If not, usually one more very slight adjustment should fix the problem.

6. Tighten the locking ring for the die and you're done. You have just set your sizing die up for a custom fit to your specific rifle, rather than a generic one size fits all guns.

Paul B.

[Unclenick]

As 44 AMP said, the technical reason for the belt was to be able to achieve headspacing without a rim in a case that had too shallow a shoulder angle to be able to headspace reliably on the shoulder. As soon as belted cases began to be made with more normal high-power bottleneck cartridge shoulder angles, the belt became redundant headspacing tech. Worse than redundant. If you look at the SAAMI chamber belt and shoulder seat specs and compare them to the cartridge specs, you realize the tolerances for belted case shoulders are greater than in rimless high-power rifle cartridges. This is to ensure headspacing on the belt and not the shoulder because the chamber's belt seat is where headspace is controlled. Thus, they don't want the case shoulder to be able to reach the chamber shoulder before the belt reaches its seat in the chamber, even when the case is worst-case large and the chamber is worst-case small. That means forming the shoulders back by the usual rimless case amount plus the worst-case maximum head clearance. All this means the shoulder in new ammunition will blow out further than it does in a normal rimless case, and if you full-length resize to return a fired case to factory spec, you will be resizing the shoulder more than you would with a normal rimless bottleneck case. That extra working helps fatigue the brass faster than in normal cases.

On top of that, when you fire a norma rimless case, the thin walls expand to fill the chamber and stick the case to the chamber walls, and the head then is pushed back against the breech face by stretching the brass right where it starts to be too thick to expand enough to stick to the chamber wall. This forms the "pressure ring," and the angle of the slope from the fatter thin part of the case down to the head isn't very sharp. But when you have a belt, that angle is turning the corner onto the belt and is thus much sharper, and a stress riser can form at its inside corner, making the case vulnerable to separating there.

[stagpanther]

I shoot quite a few belted cartridges "fathered" by the 375 H&H--I've found the Larry Willis belted magnum collet die to be indispensable in the sizing process.

[hooligan1]

I load for 7 rem mag and .300 win mag, i use RCBS dies for .300, and Forster Benchrest for 7 mag.. I have the Larry Willis die as Stagpanther mentioned..
1. Not necessary for my 7 rem mag brass, even though I check it, from time to time with the LW die..
Havent had a need yet to test .300 win mag as we havent hit that hurdle yet..
I dont know that the LW die was 100.00 well spent, unless it setting there looking on makes my dies do their jobs and not leave a bulge.. ???

[Toddco]

Great info, looks like i have extracted the life from these cases, they will now go into the brass melting pot!

[stagpanther]

I load for 7 rem mag and .300 win mag, i use RCBS dies for .300, and Forster Benchrest for 7 mag.. I have the Larry Willis die as Stagpanther mentioned..
1. Not necessary for my 7 rem mag brass, even though I check it, from time to time with the LW die..
Havent had a need yet to test .300 win mag as we havent hit that hurdle yet..
I dont know that the LW die was 100.00 well spent, unless it setting there looking on makes my dies do their jobs and not leave a bulge.. ???

IMO--the bulge ahead of the belt is simply telling you your case brass is flowing out upon expanding and conforming to the chamber. If that flow isn't contained between firings, it's just going to keep repeating itself until the space ahead of the belt because overly-weakened. A sizing die, regardless of type, can't be turned down enough to size the case to the belt in my experience. Just my opinion (after firing quite a bit of 7mm STW) cases that have a taper like the original H&H can cause a case to "hang short" on chambering, In other words, the wider taper towards the head can prevent the case from seating deeper into the chamber, especially if it's a tight one, and that too aggravates brass flow and potentially premature failure. I shoot lots of weatherby magnums,300 win mag and 7mm STW, they don't all necessarily wear predictably in the same way and may not all need the LW die all the time, it's a bit of a hassle to add to the sizing process but I don't mind it.