Melted Bullet Bases

[StarMetal]

I was reading a new gun rag and there was an article in it about cast bullets. I scanned on to the part about reason for using gaschecks. Of course it said the reason was to protect the base of the bullet and also scrape off what lead gets in the bore and grooves. The fellow went on to say he talked to the Hogdon powder company in lenght about this and here is what they said. They said the heat from the powder burning reaches about 4340.33 deg F, but said the duration is so brief that it doesn't have much affect on melting the bullet base. They used the story about passing your hand through a candle flame as an analogy. The part that was interesting is that Hogdon believes that you should use a moderately to slow burning rifle powder, because for one they said not even in peak pressure is all the powder consumed, but that the unburned powder resides against the base of the bullet and insulated it from the extreme temperature of the powder gases. Now this is something that I've been trying to tell you fellows that I believe a secondary purpose of dacron or kapok filler serves....protecting the base of the bullet from hot temperatures, along with keeping the powder positioned and I'll throw in a third.....sealing off any gascutting leaks.

Joe

[shooter2]

This is a new one on me. In any cartridge up to 2 percent +/-, of the powder is unburned. Sweep it up off the floor into a pile and put a match to it and it will burn. Why it escapes is anyones guess and I've never seen a definitive answer to that, but it does. Two percent is not much of a buffer and, why would it seemingly collect under the base of the bullet? Because it's furthest from the primer? That's a reach. Even with slow powders all the powder is going to burn (excepting the 2 % or so)before the bullet travels ten or twelve inches. Most of the energy is lost in heat. Roughly 50 %. The remaining 48 % or so does what we want and expands as a gas. Frankly, I think the time is what's critical. The heat is in contact with the bullet for such a short time that it simply does not have time to melt it assuming a proper seal and no gas cutting. JMHO

[Bass Ackward]

The part that was interesting is that Hogdon believes that you should use a moderately to slow burning rifle powder, because for one they said not even in peak pressure is all the powder consumed, but that the unburned powder resides against the base of the bullet and insulated it from the extreme temperature of the powder gases.

Now this is something that I've been trying to tell you fellows that I believe a secondary purpose of dacron or kapok filler serves....protecting the base of the bullet from hot temperatures, along with keeping the powder positioned and I'll throw in a third.....sealing off any gascutting leaks.

Joe

Joe,

Yep. Powder starts to burn from the back of the column forward. Back by that little thing that they call a primer. When the concussion from the primer goes off, the expanding gas pushes everything in front of it forward.

The amount of .... propellent burn is governed by pressure. The rate .... of propellent burn is governed by pressure. When you see a burn rate chart, that chart is established for powders burning in a controlled environment at a standard temperature. But because of ignition variables, powder may slow down from there. Or if over heated, like on a car dash, they may increase.

Two guys shooting 44 Mags with 240 grain bullets with 4227, both do not burn the same amount of powder. One guy hates the stuff because it fouls up his revolver and it burns clean for the other guy.

Why? Well one guy is getting better ignition than the other guy. The reason why is unimportant here, except that powders need pressure to burn .... at the rate for which they were manufacturered. There are powders that are designed to burn at lower pressure levels using shape to assist the chemical coating of their exposed surface areas. Like shot gun powders. But they burn eratic at higher pressures sooner .... than other shapes and burn faster in extreme cold. Blue Dot and Steel come to mind here.

I use powder for filler. But I don't think my powder is plugging any holes, so you got me there.

[StarMetal]

Bass

On filling the holes. Say there is a bad spot on the bullet side, like a scratch, that goes to the base. Say that scratch is across the whole bottom band, from lube groove to base. Powder ignites, gas pressure builds, finds this scratch and trys to get up through it. I think a fiberous filler like kapok or dacron, being it's fills the space between the top of the powder and the base of the bullet, which thus means it's ahead of the "burn" gets pressed into these almost microscopic deformaties and seals them. Seals them at least better then if there were no filler at all in the case. Kind of like stop leak in a radiator or platlets in your red blood cells to plug cuts. That's what I meant.

Joe

[waksupi]

Do you suppose Elmer Kieth had the answer, with drilling and tapping the primer seat? He then threaded them, and put in a copper or brass tube, to put the primer flash well up into the case. Supposedly, he got cleaner burn, more consistant SD's, higher velocity per grain of powder, less throat erosion, and could run faster and jump higher. I do believe there are several artillery shells using this type primer set up. Anyone ever played with this?

[Willbird]

Actually the Newton rifle ctg. used flash tubes I'm told

Bill

[Buckshot]

............I know the 3"/50 and 5"/38 semi fixed ammunition had a tube inside the case to bring the primer ignition up to the plug in the casemouth. The top 4-6" of this tube had radial holes in it.

An interesting thought just now. I was no gunner's mate, but I have seen the 5 inchers worked in drill with dummy ammo. The projectile is placed in a tray maybe 3' from the breech, and it's hydraulicly rammed into the barrel (chamber, leade, throat. SOMEWHERE up there :-). Then the powderman lays the case (looks like a big 300 Savage case. Short neck) in the tray and it gets rammed in and then the breech closes. BTW, the breech is a wedge deal and not an interupted thread type.

What I was wondering is, is the projectile merely smacked up into the rifling via momentum? The hydraulic ram is flat faced and only goes up to the breechface. Or, does the ramming of the case push the projectile into it's correct position? I'd think the later, otherwise the projectile could be at widely different positions due to friction from firing residue, barrel heat, bore wear, etc. Anyone know for sure?

..................Buckshot

[StarMetal]

Buckshot

I don't know what kind of 5 inchers you had on your ship, but ours sure weren't like that. The 5 incher case is straight, looks like a giant 357 mag. Now the 3 incher is necked and looks kinda like a 303 British. I know for sure the 3 inch ammo is assembled, that is projectile put in the case mouth, because on the twin 3 inch cannons there are cylinders for each barrel that rapidly feed them as this is an anit-aircraft gun. Those cylinders are open sided and there are six chambers. I'm not sure on the 5 inchers, as I've never seen them practice. I have handled the projectiles and they are about 48 pounds and have two big brass rings on them to catch the rifling. The brass came in an aluminum canister, I guess charged and ready to go. I had assumed the projectile and casing got put together somewhere along the line. You mentioned watching the gunnersmate practice with dummy ammo. Did they actually ram the projectile? If so how did they get it back out?

Joe