So, a derringer is a small pistol, usually with two shots, made for close-range self-defense. Normally they use, well, pistol rounds, like a 9mm, which has like, 700 joules of energy or someshit like that. When you fire a lightweight gun, you definitely get some kickback from it, even with a pistol round.
A 45-70 is a big-ass rifle round with something like 4000 joules of energy behind it. You uh, you put that in a little derringer and pull the trigger, both you and your target are gonna feel it.
Does the slide absorb any significant amount of energy?
The spring can't be all that strong since they can be assembled by hand, and what does the slide weigh? (Granted the slide is being accelerated, so I assume that's where the bulk of energy is dissipated, MV^2 and all).
What's the math on this, say the dissipated energy in a semi auto VS revolver using the same round?
(Really I'm curious what the numbers are, as I've read this many times but have no idea what the comparison is like).
Remember conservation of momentum. The only way the machine can absorb part of the impulse is through friction, heat, and by redirecting the existing chamber pressure after the bullet has left the barrel.
Remember the human body. Magnitude matters much more than duration. Extending the time of impulse by implementing a slide lessens magnitude, the areas under the impulse curves roughly equivalent.
I'm going to apply the above to answer your questions to say it again :)
Does the slide absorb any significant amount of energy?
For a properly functioning, modern, and typically-designed pistol and a status quo definition of "significant", the answer is: No. That's not what it's designed to do. But, energy can be dissipated slightly if the pistol is compensated: a redirection of chamber pressure from near the end of the barrel, upwards, counter the torque component of the recoil impulse.
What's the math on this, say the dissipated energy in a semi auto VS revolver using the same round?
It's not quite a good question. The maximum force during the impulse is what a human cares about when analyzing a slide. That's what'll effect accuracy of the next round and how sore your hands will be in the morning.
If minimization of total impulse is what's being analyzed then one would want to compare rifles. Rifles have larger rounds, longer barrel length thus more time to use chamber pressure to mitigate recoil.
You've good questions for coming into the middle. Go to the beginning: rounds and various types of actions, rifleman 101. Come back to the hard science.
I've heard many times that revolvers or semi-auto have less recoil than the other, hence the question about slide mass/energy, as the only element I could see being different which could possibly explain why people hold this opinion.
Do you know of any actual metrics/tests done that show this clearly? Or is it just a perception issue?
(And yea, we'd have to agree on a definition of what we're measuring/comparing). Do any gun magazines run proper tests occasionally to make comparisons?
I admit my physics classes were a long time ago, but at first glance it seems felt recoil would only be marginally different between a revolver and a pistol using the same round. If anything, I'd expect the revolver to have a greater felt recoil, given the mechanics of a pistol... But I could very well be wrong.
Do you know of any actual metrics/tests done that show this clearly?
No one probably cared to design a barrel and firing mechanism just for this experiment since maybe the late 1930s. And, I'd guess that possible someone was the US military.
Honestly, no one really cares. There's so many variables that change slightly for each cycle of the action. Variables change more for each round, assuming typical ammo. And, there's a lot of variables that change a helluva lot between humans. After deciding usage and the appropriate round to chamber, one starts picking their pistol based on what feels good in their hand. Those are the ones they'll shoot most accurately with.
my physics classes were a long time ago
The hardest part by far is visualizing a graph. Force is the y axis. Time is the x axis. A line represents a changing force over time called an impulse.
Impulse 1: acts with a force of 1000 Newtons for 0.01 second
Impulse 2: acts with a force of 10 Newtons for 1 seconds
The impulse magnitude is the integral, the area under the curve of the graph of force over time. The math is easy for these situations because they're rectangles: 10 x 1 and 1000 x 0.01.
Both impulses have the same magnitude: 10 Newton x seconds. Both impulses, applied upon a mass, can do the same amount of work. Both impulses could be the equal and opposite reactions to firing the same round if fired from different pistols.
The revolver delivers a short, violent, mess of peaks and vallies along a big peak. The modern semi auto delivers a smooth increase to a lower plateau that falls off just as smoothly. The modern semi auto takes much longer deliver the same magnitude impulse.
But, a human brain and body doesn't care much about "much longer" when it's still "instant". The brain and body care about the how high the peak is and how "messy" (signal noise).
Do they typically even use something with as much energy as a 9mm? I thought they were typically smaller rounds like 38 or 22, since it's a close range gun?
I really don't know anything about them, would be interesting to see a chart of them.
Mostly I was just grabbing a pistol cartridge that I was vaguely familiar with to demonstrate the difference between a 'normal' round for a handgun and a 45-70.
modern loadings do that, but the original loadings were black powder and had energy comparable with today's 5.56. 5.56 still has much less recoil because it's lighter
No problem! That particular derringer is special-made to hold a 45-70. A more typical derringer would look more like this or this.
Really, the only use case I can think of, other than "I like shooting powerful rounds", for the 45-70 is big-game hunting or self-defense against bears, lmao.
Make me wonder how it would compare to a 410 round. I have shot those and they were not fun in a pistol. That pistol was considerably heavier then a Darringer too
Holy shit, the unburned powder on the ballistics gel block!
This one should bookend that rifle with the crazy long barrel they keep sawing pieces off of while monitoring muzzle velocity.