Grenadier---Yes I misquoted you---I left off that gas checks are loaded behind the bullet and that gas checks are hard. Oh and that is in rifles.

quote:

Originally posted by carpetman1:
Grenadier---Yes I misquoted you---I left off that gas checks are loaded behind the bullet and that gas checks are hard. Oh and that is in rifles.

It was, "Even the expansion of a soft lead bullet is not sufficient to seal off gases adequately in a rifle. That is why we load them with gas checks behind them. The gas check is hard."

Gas cutting is caused by jets of hot gases and particles finding their way past the base of the bullet. Comparing passing a bullet held by pliers through a flame to what happens in a rifle barrel is meaningless. Not only is the burning temperature of natural gas about 1500° F lower than that of smokeless powder but your flame is at 1 atmosphere of pressure while the pressure in a rifle bore is thousands of times greater. It's like comparing passing your hand under the hot water faucet to putting your hand inside a steaming pressure cooker. Did you know that even cold water can will through rock if directed at in a tight, high pressure stream?

I hope that someone did not mistake my misquote to think that a soft gas check is installed on the nose and it was for pistols only. Yip, your quote said they were hard and mounted behind.
Natural gas cutting torch? So how do you explain the lube not melting?

quote:

Originally posted by carpetman1:
I hope that someone did not mistake my misquote to think that a soft gas check is installed on the nose and it was for pistols only. Yip, your quote said they were hard and mounted behind.
Natural gas cutting torch? So how do you explain the lube not melting?

Of course nobody would think " a soft gas check is installed on the nose". You're just trying to be facetious.

You misquoted me as saying, "A soft lead bullet is not sufficient to seal off is why gas checks are used".

That means something very different from what I said, " Even the expansion of a soft lead bullet is not sufficient to seal off gases adequately in a rifle. That is why we load them with gas checks behind them."

Earlier in the thread we were speaking of differences between shotguns and rifles and I had said that shotguns used soft wads for gas seals whereas rifles do not.

An oxyacetylene torch burns about the same temperature as smokeless powder but that still doesn't account for the significant pressure difference.

Regardless of your bullet and torch test, gas cutting of lead bullets does occur. It occurs because the gasses are not adequately sealed by the base of a soft lead bullet. And one of the purposes of the gas check is to prevent that. But if you don't believe Lyman about it I don't expect you to believe me.

Grenadier---Lyman sells gas checks. You think they are going to bad mouth them? I don't. I think flowery things and create a need for them so people will buy them. Do you really think they can take wheelweights of unknown composition and use it for 95% of their Lyman #2 and to this 95% UNKNOWN add 5% of exacts and come up with an exact? I don't. I think it would be amazing if they could. BTW I have found some misprints in their load data.
I still don't see how I misquoted the meaning of your message one iota with my paraphrase.

Grenadier--google acetylene/oxygen torch and it's about 6332 F which is about double smokeless powder. You wont melt lead in a brief instant. If it isn't sealed how is it under pressure?

This whole thread is like asking when is a tadpole a frog?

quote:

Originally posted by carpetman1:
Grenadier--google acetylene/oxygen torch and it's about 6332 F which is about double smokeless powder. You wont melt lead in a brief instant. If it isn't sealed how is it under pressure?

If it wasn't under pressure the slug/bullet wouldn't move! If the slug/bullet couldn't move then the pressure would get so high the system would fail, perhaps catastrophically. Common pressures in shotguns are generally on the order of 7,000-12,000 psi and in rifles 40,000 to 60,000 psi, though there are cartridges that operate at pressures higher and lower than those numbers.

The relationship can be expressed as the combined gas law:

PV / T = C

Where P is the pressure, T is the temperature, V is the volume, and C is a constant. A doubling of the pressure will double the temperature. That's why tires get warm while inflating and why scuba tanks get hot when filled. In both of those examples the filling process takes considerable time and all the while heat is dissipating. Pumping up a tire or filling a scuba tank would be very much different if the pressure change happened in milliseconds.

Consider this example. In a shotgun, several inches into the bore the pressure between the base of the hull and the rear of the slug or load will be about 700 times greater than before firing, i.e. an increase from about 14.7 psi to over 10,000 psi. If the volume of the gas behind the slug/load also increases at that point down the barrel to 10 times the original volume then that increase in volume would still leave gas pressure in excess of 70 times atmospheric pressure. The temperature of the burning gas under extreme pressure at that point is considerably higher than the powder burning temperature at standard atmospheric pressure by many orders of magnitude. This is a simplistic example but it serves to illustrate the fact that temperature of gas behind a fired slug in the confines of a gun barrel are considerably greater than powder burning temperatures in the open. Gas pressures in rifle barrels are even greater still as well, as are resultant gas temperatures.