Would like some help with a few things.

[G36-UK]

Hi guys,

I don't really know where to put this, so if I'm wrong, sorry to the mods for the trouble.

I've been reading up on various firearms for research (and so I don't balls it up) in regards to a story I'm writing.

I've got a few questions and I suppose this is the best place to ask them.

First, Necking down; I've read in some places that there are necked down bullet casings, like a .44 Automag fired a necked down .308 (is this right?), a .357 Sig is a 9mm in a necked down .40, and the .440 CorBon is a .44 in a necked down .50AE.

What is the advantage/disadvantage of a necked down round, if any?

Has anyone had personal experience with the CorBon ammo? What were your thoughts?

Second, I've been looking at the Box of Truth website, and I notice the writer of the articles has a rifle called a Sharps in .45-70.

What is the capacity, and how does it load (ie. Bolt-action, lever, etc)?

What does the gas check on the bullet do?

Thanks for helping. I may have a few more questions later.

 

[carebear]

Correct me if I'm wrong guys.

The Automag isn't so much "necked down" as it is chopped off. The rifle case is thicker (stronger) and thus allows for higher pressures than typical pistol brass, which increases velocity. Cheaper than making new brass specifically for the round.

Necking down allows for greater case capacity than a cartridge of near bullet diameter (more powder to burn) while also providing a venturi effect to increase the pressure behind the bullet. That increased gas is pushed through a smaller outlet thus propelling the bullet faster without increasing as dramatically the case pressure.

CorBon has been a quality specialty ammo manufacturer since the 70's (80's?). In the early days, before all the big manufacturers came to their senses, they were one of the few sources for +P level pistol ammo.

The Sharps is a single-shot, falling-block breechloader. In black powder days they were highly powerful and accurate hunting arms, "buffalo guns". See "Quigley Down Under" with Tom Selleck for a good movie representation.

The gas check on a cast lead bullet is a small disk, usually copper, that prevents the hot propellant gasses from simply chewing up the soft lead bullet base and instead push it out the barrel. a bit of armor for the lead so to speak.

 

[MikeJackmin]

1) Necked-down rounds: Keep in mind that this is something that is of concern to cartridge designers, not really to the users. The short answer is, for various reasons, sometimes it is useful to invent a cartridge with a specific shape. If that shape can be easily manufactured by necking down the casing for an existing cartridge, than they might do this. In general, there is nothing special about a neck-down cartridge as far as the user is concerned.

In general, such cartridges tend to throw small bullets at high speed.

2) CorBon is a well-respected provider of high-performance ammo. They also have developed some cartridge designs of their own.

3) A Sharps is a single-shot rifle, using a type of falling block (?) action, I think. It was developed in the mid to late 1800s and was employed as a buffalo rifle. Used as a retro target rifle now, often with old-fashioned black powder instead of modern smokeless powder.

4) Soft lead bullets sometimes perform better with a copper cup placed over the base, to protect it from the heat and pressure of the burning gunpowder. The little cup is called a gas check.

This is something that would be familiar to a guy doing target shooting with his .45 Sharps rifle, because he's likely to reload his own ammunition.

 

[RevDisk]

In general, such cartridges tend to throw small bullets at high speed.

Yep. That's generally the idea.

What is the advantage/disadvantage of a necked down round, if any?

Higher velocities, generally. Disadvantage? I'm not exactly sure, but I imagine it wear down a weapon slightly faster. In most modern rifles, I don't think it'd be an problem you'd really notice unless you fired an insane amount of rounds.

Has anyone had personal experience with the CorBon ammo? What were your thoughts?

Not bad, good quality ammo. Bit too expensive for my tastes, considering I like to shoot a lot. I refuse to carry ammo different than what I practice.

Some people like to think CorBon ammo causes insane amounts of damage when it hits a person or animal. One guy tried to convince me that .45 ACP CorBon ammo could stop a charging bear. Uh, ok. Maybe, but I sure wouldn't try it.

 

[Azrael256]

IIRC, .357 Sig is not a necked .40. The cases have the same rim, but their lengths (before necking) are different. I don't recall exactly, but I think the case lengths (completed cartridge) come out the same. It's not the same thing as the .440 Cor-Bon, which, to my knowledge, is simply a .50AE case necked down to .44.

As MikeJackmin said, I don't see anything really special about necked rounds (in pistols). I could see the .440 Cor-Bon being better for hunting than the .50AE, as it probably has a flatter trajectory, and better than the .44Mag because it carries more energy. I haven't done any ballistic testing or anything, and pistol hunting isn't my thing, so I'm basing that on my own reasoning and not hard data. YMMV. Beyond hunting applications, I could see a fine use for it in the "it's loud, powerful, and really cool" category.

Immediate practical considerations aside, there is great value in trying out new designs. It gets us better stuff in the long run. The idea of a bottleneck cartridge came about around the turn of the century (1900-ish. I can't pin it to an exact date or weapon, so I could be off), and is the basis for all modern rifle cartridges. Prior to that, many rifles fired the same cartridge commonly found in pistols, or used what appears to be a beefed-up pistol cartridge. Necking a cartridge gives us the high-velocity, flat-trajectory rifle rounds we use today.

 

[mnrivrat]

Just to clarify , the Sharps falling block action is activated by a lever that also forms the trigger gaurd.

It was a heavy caliber rifle who's cartridges are often designated by using not only the bullet diameter and powder weight, ( 45-70 being .45 caliber loaded with 70 grns of powder) but included the bullet weight and the case length as well. It's largest (special order) caliber was in .50 with a case length of 3&1/4 inches as I recall.

I'm not remembering the bullet weight of the .50 , but the powder charge could be as high as 140 grns .

 

[CB900F]

Fella's;

I'll heartily agree with carebear on the "isn't so much "necked down" as it is chopped off.", concerning the .44 Automag. The .44 jacketed bullets run around .430" in diameter according to various manuals. The exterior neck dimension of the .308 is .343"/.344" depending upon your source. Very hard to get a .3435" neck down to .430". However, the body of the .308 brass tapers from .470 at the web to .454 just before the shoulder. I don't have the cartridge dimensions of the .44 Automag at hand, but it shouldn't be any great feat to chop off the .308 & create the case for the Automag in an industrial operation.

900F

 

[entropy]

They were made by cutting .308 brass down to whatever the length was (I'm have an almost-senior moment), and inside reaming the case to the diameter of the bullet.

 

[DonNikmare]

I have to give Carbon ammo the thumb down. The longer overall length cartrages caused a lot of FTF's in one of my auto's. A SP-01 owner had an unfired round stuck in the chamber, after loading up at home.

Would probably be fine in a revolver but reliability will vary in semi-autos. If you like them, test them in your personal weapon before trusting them.

 

[Dionysusigma]

Azrael256:The idea of a bottleneck cartridge came about around the turn of the century (1900-ish. I can't pin it to an exact date or weapon, so I could be off), and is the basis for all modern rifle cartridges.

I'm thinking it was before then. The Martini fired a .450, which had a smaller case mouth than rim... and that was in the late 1880s.


Click for a larger picture
From http://www.svartkrutt.net/engmartinihenry2.php , with a .22lr on the left.

 

[Azrael256]

I got all excited when I saw that picture. I thought you had bought a Martini that we could play with when I get back to school. *sigh*

 

[Wiley]

One of the first, if not the first, necked-down or 'bottle necked' cartriges was the '44WCF' (Winchester Central Fire) aka '44-40' (.44 bullet diameter-40 grains of black powder). It was developed in the 1860's as a rifle cartrige and subsequently used in revolvers.

The most notable rifle was the Winchester Model 1873 rifle. In revolvers the 1875 Remington stands out.

As a side note: The 44-40 and 44 Magnum are NOT interchangable.

In modern cartriges the 30-06 gave rise, I think, to the .308 family. A whole series of necked down cases are based on the .308 (.270, .243, etc.)

Many of the reloading manuals give a short history of many cartirges.

 

[Dionysusigma]

Azrael256 I got all excited when I saw that picture. I thought you had bought a Martini that we could play with when I get back to school. *sigh*

Wish I did... Don't know where they're available from, tho. Plus, ammo is quite hard to find, IIRC; unless some have been rechambered to .45-70 or .303 or somesuch.