Brief video of wads & shot charge exiting a bare bore

[roundball]

Double click the image, then Photobucket will load it up...

 

[Lonegun1894]

Do you by any chance know the exact load? Looking at it, it appears as if the OP card separates fairly quickly, but there is a wad (?) that seems to be pushing into the rear of the shot load and appears to be spreading the back end. Is this what it looks like when people talk about a heavy wad pushing into the rear of a shot load and thereby blowing what would have been a good pattern? Very interesting, and educational. Thanks!

 

[Alden]

Love that.

Aren't they the folks with that 10 minute video of bullets hitting metal plates and armor to music in super slow motion?

Amazing stuff...

 

[roundball]

Do you by any chance know the exact load? Looking at it, it appears as if the OP card separates fairly quickly, but there is a wad (?) that seems to be pushing into the rear of the shot load and appears to be spreading the back end. Is this what it looks like when people talk about a heavy wad pushing into the rear of a shot load and thereby blowing what would have been a good pattern? Very interesting, and educational. Thanks!

I have no further details...but the website is listed in the video

 

[Wes/Tex]

The fiber wad doesn't appear to be actually pushing into the shot cluster but moving at the same velocity with the obvious flats on the outside pellets that will cause them do fall away at a distance. I don't believe the often referred to 'wad pushing through the shot' is actually what occurs, it being lighter than the shot and prone to more rapid deceleration. I've used Spence's load with a lubed wad for years, even before reading his fine work, can't say I've noticed a great difference with or without the lubed fiber wad in longer barreled fowlers...42" to 46" barrels.

 

[Alden]

Same reason I load buck behind ball -- the ball WOULD push through the buckshot and does neither any good. And I use the right number of the right size so they cannot wedge in the barrel!

 

[BillinOregon]

I'm with Wes on this. The rear of the charge is being partially spread by the cushion wad, which after all is the "piston" that transfers the power of the combusting gases to the shot charge, with all its inertia. It still has just enough thrust to cause some of the slower and much heavier shot to try to get out of the way for an instant. But a lot of that spreading is also the effect of the shot that have been abraded as they travel up the barrel in contact with it. This friction has had the effect of trying to "brake" them as much as possible, and as they smeared their way up the bore, they would have been pulled to the rear at the instant the column leaves the barrel.

Alden, perhaps a topic for another thread, but your idea of putting the buck behind the ball makes sense. I'd love to see side-by-side targets and chronograph results of "in front" and "behind."
Would think you need an overpowder wad with the buck behind, though.

 

[Gunner Mercer]

I taught ballistics at USMC SCHOOLS and The US
ARMY INFANTRY SCHOOL ! I'm not saying if your right or wrong! Please study the evolution of firearms and Civil War Evolution to Modern Firearms, also the evolution of paper cartridges to foil cartridge, to brass cartridge. The last being the class I personally taught if any of the students were awake (and i'm positive they were).
Gunner Mercer

 

[Gunner Mercer]

Here is a hint- study- Kenetic energy, why do we weigh projectiles and propellant! Hope this helps.

 

[TinStar]

Or it could be that the front of the shot column is pushing back into the rest of it due to the resistance of the air it is pushing against? Isn't it the front of the column that is facing the air resistance first?

TinStar
Soli Deo Gloria!

 

[roundball]

Here is a hint- study- Kenetic energy, why do we weigh projectiles and propellant! Hope this helps.

You posted this reply to me specifically and it appears to be an attempt to answer a question I didn't ask.
Did you have some other thought in mind?

 

[Grandpa Ron]

The old maxim of “thinner wad and less powder produce the tighter the group” could be due to a lot of things, but I have never seen a high speed photo of the wad pushing through the shot.

I believe that bore scrubbing and air resistance play a part but experienced shot gunners will tell you that; just like a rifle, there are some loads that perform better in any given shot gun.

 

[410-er]

Do we know the actual powder/shot charge?
My computer didn't open it.

 

[MikeEasy]

While inside the barrel, the shot train is constrained and cannot spread out (the barrel holds it in). But once the leading edge of the shot train begins to exit the barrel, the following shot and wad (still in the barrel and still under pressure) is still accelerating and will push any shot ahead either forward or to the side. This happens for only a very brief period since, once the wad exits the barrel, the pressure behind the wad drops to zero.

The picture and movie show the shot train after it has exited the barrel completely and so do not show lateral dispersal of the shot occurring (although they _do_ show that lateral dispersal has already occurred).

Suppose the the shot and wad are one inch (1/12 foot) in length and the muzzle velocity is 600 feet per second. Then the leading edge of the shot train exits about 1.3 ten-thousandths (1/12/600) of a second before the wad exits. During that brief period the shot in the leading edge of the shot train is being "pushed out of the way" of the shot/wad behind it that is still in the barrel.

It's kind of like people pushing their way out of the door of a burning theater - the ones in the doorway and just outside are being pushed by those behind them and they accommodate the pressure by moving forward and/or to the side.

 

[coloradoclyde]

I have a question,
Where's the overshot card?