Gas: Extruded vs Spherical

[Bart B.]

Just for fun, I ran both of the powders in QL, with equivalent peak pressures, and you can see how the two compared.

Isn't the difference the typical spread either load will produce by itself?

Or maybe its more.

 

[MagnumManiac]

Those QL values are what the powder makers gave as their temps from a calorimeter bomb.
This device is NOT a firearm or cartridge. It does NOT explode, it simply measures the gas volume, heat and pressure of a pre-determines amount of powder.
I have first hand experience in doing these.
The temperature recorded is NOTHING in comparison to what the powder burns in a barrel. The pressure is many thousands more in a cartridge when fired, in fact, the gas temp is hotter than the temp at which steel actually BURNS, not MELTS. The time is so short that very little damage is done during firing of each cartridge, but it is accumulative.

So the charts showing flame temps do not take into account the cartridge being used, the pressure it’s being used in and so forth.
Whereas the military tested flame temps between extruded and ball in both 5.56 and 7.62 and the ball was considerably cooler, decreasing throat erosion.

You can look this up yourself.

Cheers.

 

[MagnumManiac]

Those QL values are what the powder makers gave as their temps from a calorimeter bomb.
This device is NOT a firearm or cartridge. It does NOT explode, it simply measures the gas volume, heat and pressure of a pre-determines amount of powder.
I have first hand experience in doing these.
The temperature recorded is NOTHING in comparison to what the powder burns in a barrel. The pressure is many thousands more in a cartridge when fired, in fact, the gas temp is hotter than the temp at which steel actually BURNS, not MELTS. The time is so short that very little damage is done during firing of each cartridge, but it is accumulative.

So the charts showing flame temps do not take into account the cartridge being used, the pressure it’s being used at and so forth.
Whereas the military tested flame temps between extruded and ball in both 5.56 and 7.62 and the ball was considerably cooler, decreasing throat erosion.

You can look this up yourself.

Cheers.

 

[johnfred1965]

Just a WAG here in the middle of the night. Say you have the same weight of the same powder at the same pressure. When burned, you end up with the same weight of gas and thus the same volume. Change the weight of the load, at the same pressure, you change the volume. Change the pressure with the same load, you change the volume. As Kevin T said, the powders are essentially the same material when they are solids, so you will have similar (not identical) volumes. Your differences come with the speed the powder burns, or how fast the weight of the solid becomes the same weight of a gas. This leads to different chamber pressures, area under the pressure curve, timing and intensity of the port pressure and of course the velocity of the bullet. Again, as Kevin said, much of the difference in weight is the the deterrent coating, that can add weight to a powder charge, but will end up as residue in your barrel rather than converting to that similar weight of gas, so you will have some minor variations in volume for that reason. The big thing though, is the action of the powder with these coatings and the effects on burn rate and pressure application.

Maybe more than $.02 but just something else to think about. This was just a spitball, and no actual science was harmed in its production!

Here is a little real science, right off of Mythbusters: Water will expand 1700 times when converting into steam. Makes those exploding water heaters on the show as cool as one ragged hole in your target!