180 grain 357 and short barrel

[MCgunner]

Cos is right. I wouldn't carry, nor did I develop it, my 180 XTP for self defense. I developed it for hunting medium game, deer and hogs, with my 6.5" Blackhawk.

 

[ATLDave]

Ah, Cosmoline, maybe we had a miscommunication. I certainly did not mean that the powder needed more burn time to impart higher velocities, just longer time with the bullet in the barrel.

 

[Deaf Smith]

The bullet gains velocity in longer barrels, but not because of "unburned powder" as some have suggested. The smokeless burns almost instantly, but the velocity increases as the gas forces the bullet down the bore.

No it does not burn instantly. Black power does but not smokeless.

Example.. look at any gun fired with slow burning powders and you will see flakes of UNBURNT powder on and inside the gun. Especially 2400 powder.

Deaf

 

[MCgunner]

Definitely the magnum revolver powders BURN slower than stuff like Bullseye that is used best in calibers like 9x19 or .45ACP. You can tell that by the fireball at the muzzle. Smokeless is classified as a "propellent" vs black powder which is classified as a "low explosive" (fast burner).

 

[Cosmoline]

Those bits of crud are residue and debris from the combustion that won't burn no matter how short or long your barrel is. The powder does NOT need barrel length to "finish burning." The expanding gasses accelerate the round as the round goes down the barrel. So the longer the barrel, the more velocity you get.

look at any gun fired with slow burning powders and you will see flakes of UNBURNT powder on and inside the gun. Especially 2400 powder.

I think you're seeing what's left of the chemical reaction. It happens VERY quickly. But let's say you're right and the 2400 didn't all burn up. Do you think a longer barrel makes any difference to that effect? In other words, do you think little bits of unburned 2400 are igniting in the barrel and pushing the bullet along as it goes? Conversely, do you think that the powder just gives up when the bullet leaves out of a short bbl and stops burning?

Logically it has to be the expanding gasses. As long as the barrel is sealed with the bullet they keep pushing it faster and faster forward as they expand more and more, but once the bullet exits the gasses, following along behind, explode out and no longer accelerate the bullet. That's why, as I understand it, the longer the barrel the faster the bullet--up to a point.

 

[Deaf Smith]

Those bits of crud are residue and debris from the combustion that won't burn no matter how short or long your barrel is. The powder does NOT need barrel length to "finish burning." The expanding gasses accelerate the round as the round goes down the barrel. So the longer the barrel, the more velocity you get.



I think you're seeing what's left of the chemical reaction. It happens VERY quickly. But let's say you're right and the 2400 didn't all burn up. Do you think a longer barrel makes any difference to that effect? In other words, do you think little bits of unburned 2400 are igniting in the barrel and pushing the bullet along as it goes? Conversely, do you think that the powder just gives up when the bullet leaves out of a short bbl and stops burning?

Logically it has to be the expanding gasses. As long as the barrel is sealed with the bullet they keep pushing it faster and faster forward as they expand more and more, but once the bullet exits the gasses, following along behind, explode out and no longer accelerate the bullet. That's why, as I understand it, the longer the barrel the faster the bullet--up to a point.

http://www.firearmsid.com/A_distanceGSR.htm

Read about UNBURNED Powder particles:

"Gunpowder residue can contain unburned gunpowder particles, partially burned gunpowder particles or the carbonaceous soot from completely burned gunpowder. The image below show a bullet hole surrounded by gunpowder particulate residue."

http://www.forensicscienceresources.com/Shooting.htm

"A contact shot to a target produces tearing, a large amount of burning, and unburned gun powder particles deposited in the bullet tract. "

http://library.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNGSR.html

"The residue of the combustion products, called gunshot residue, can consist of both burned and unburned primer or powder components, and can be used to detect a fired cartridge."

And this explains why.

http://en.wikipedia.org/wiki/Internal_ballistics

"Using powder that is too fast creates a destructive pressure spike that usually has a very short duration. Using powder that is too slow produces poor energy and leaves a lot of unburned powder."

If you want less unburned power, say 2400, crimp the bullet in heavier so more of it burns before the bullet is released from the case by the crimp.

Deaf

 

[Cosmoline]

OK, but assuming the residue is unburned powder, what does that have to do with the bullet losing velocity in a short barrel? If the powder doesn't burn immediately, is it really going to be burning as it goes down the barrel? And is that what is TRULY making the bullet go faster as it goes down a longer bore?

Is there any relationship whatsoever between the length of the barrel and the amount of unburned powder?

 

[voicomp]

I know I am derailing a bit but I had a holster dealer try to persuade me there were no SP101's under 3". Just another Caveat Emptor alert....

 

[Deaf Smith]

OK, but assuming the residue is unburned powder, what does that have to do with the bullet losing velocity in a short barrel? If the powder doesn't burn immediately, is it really going to be burning as it goes down the barrel? And is that what is TRULY making the bullet go faster as it goes down a longer bore?

Is there any relationship whatsoever between the length of the barrel and the amount of unburned powder?

Pressure curve Cosmoline.

Since it is a progressive burning power it raises the pressure higher as the bullet moves down the barrel (and it's velocity speeds up as a result.) It is not a constant PSI (or really CUP) all the way down.

The unburned power simply did not add to the pressure curve and it just blows out the barrel (or into the action in many cases.)

Deaf

 

[Super Sneaky Steve]

I know I am derailing a bit but I had a holster dealer try to persuade me there were no SP101's under 3".

I have three. A simply rugged, a fobus and a crossbreed.

The following info I posted elsewhere, but I'll put it here too.

Ruger SP101 3"
180gr XTP 13.4gr H110 953fps 362ft/lbs

This was an average of 5 shots. Very mild recoil for a magnum load and very accurate as well.

I bet I could get much better numbers with my Bufflao Bore ammo but I'm afraid to touch one of those off in my snub.