Do cartridge case dimensions affect recoil?

[Akmtnrunner]

Not sure what your point is, but pressure is as relevant to recoil as gravity is to our weight. I was just pointing out how going into the nitty grittiness of the mechanics by addressing pressure, does agree with the conservation of energy principle.

 

[Mikecr]

No, pressure has no mass

 

[Akmtnrunner]

No, pressure has no mass

Of course not. The metaphor goes like this: Since Pressure X Area = Force, and Gravity X Mass = Weight, pressure is to gravity as area is to mass.

Here's another metaphor. You're saying chemical energy in fuel is transferred into kinetic energy of the car moving, and besides loss from inefficiencies, the amount of energy is equal. Awesome. Now I'm saying that that process includes combustion that creates a mechanical force which is directed through the drivetrain onto the road and caused acceleration, velocity, and kinetic energy. Both descriptions are correct and not mutually exclusive. One just goes into finer detail.

If you still have a hard time acknowledging that pressure is relevant to recoil, then what is the connection between the bullet and the rifle that equal and opposite forces act upon themselves?

 

[hemiford]

Something else to realize: Both energy and momentum are conserved
(physics), but energy is not a vector quantity, momentum is a vector.
The vector quantity is what you feel on your shoulder.
Energy is mV^2, but Momentum is mV.

 

[Jimvo]

Something else to realize: Both energy and momentum are conserved
(physics), but energy is not a vector quantity, momentum is a vector.
The vector quantity is what you feel on your shoulder.
Energy is mV^2, but Momentum is mV.

CORRECT! Translational Momentum (recoil in a straight line) is just mV. This means that the momentum of a weapon's reaction will exactly equal the momentum of the bullet and powder gasses ejected from the barrel in a straight line. However, the vector that you feel at the shoulder is Force, which is a factor in bullet energy (F x d) where d is barrel length and equivalent to 1/2mV^2.
Momentum is an intellectual construct that helps physicists understand the interaction of pieces of matter, but it does not exist as a real entity. Moreover, momentum is the result of the mathematical differentiation of the energy equation in any case.
There is a huge disconnect between the recoil that is predicted mathematically and what actually happens in the real world. Under the simplest conditions, the weight (actually the mass) and the geometry of a weapon are crucial factors in the recoil equation. Weapon mass is inversely proportional to felt recoil. Increase the weapon weight and decrease the recoil from the same round.
The recoil from the bullet being fired and the propellant gases exiting the muzzle should ideally act directly down the centerline of the barrel. The primary reason for muzzle rise is angular momentum for nearly all firearms. The centerline of the barrel is above the center of contact between the shooter and the firearms' grips or stock. If that line of force is above the center of the shooter's hand, a rotational force causes the firearm to rotate, and the muzzle end to rise upwards. The upward rotation is imparted by the fact that most firearms have the barrel mounted above the center of gravity. Reducing the vertical distance between the barrel and the point of grip and adding more ergonomic contact points, such as a buttstock, can help to reduce muzzle rise. When the Thompson Submachine Gun first entered production as the M1921, its rapid fire and energetic .45 ACP caliber bullets caused it to rise in the extreme in two dimensions when fired in automatic mode. For a right-handed user, the muzzle tended to move up and to the left. Thompson had intended the weapon as an automatic "trench-broom" to sweep enemy troops from the trenches, filling a role for which the Browning Automatic Rifle (M1918 a.k.a. BAR) had been proven ill-suited. In 1926, the Cutts Compensator (a recoil brake) was offered as an option for the M1921 model. The M14 issued in Vietnam initially exhibited a similar problem in full auto mode. (Sorry for being so long -Physics professor for 47 years).

 

[Jimvo]

I was recently having a good natured discussion on another thread about whether cartridge case dimensions affect recoil. I don't think so but I've been wrong before. So educate me if I'm wrong.

My impression is that recoil is dependent on rifle weight, bullet weight and velocity, and weight of powder charge. There could be other minor factors affecting recoil but cartridge dimensions is not one of them.

The other view expressed, as I understand it, is that if all other things are equal, a short fat case will have more recoil than a long thin case. Reason being that the short fat case has a larger case head. Thus with equal psi the force pushing back on the bolt is greater. Thus greater recoil.

I feel that until the bullet leaves the bore, pressure in the case is pushing equally in all directions, including the base of the bullet, and these forces, fore and aft, cancel out. After the bullet leaves the bore the jet effect of escaping gases greatly affects recoil. But prior to the bullet leaving the bore internal forces don't affect recoil.

What do you guys think?

Case dimensions alone should not affect recoil. Pressure acts in all directions in the chamber, but pressure (and the force it creates on a surface area) are not factors in recoil momentum.

 

[SMK1000plus]

By the way, keep your velocity down, these equations go out the window as velocity of bullet approaches speed of light, something that really worries some scientists!

OH NO! Not the dreaded CREEDMOOR!

 

[Swamplord]

Recoil ? It's a fear factor thing,

some of us accept reality and acknowledge that's what occurs when powder is ignited and shoves a bullet down the bore, and is completely harmless as the bullet races away from the shooter, not at the shooter

others call it "kick" and magnify it's effects with over exaggerated hysterics once thought only women possess

fear of recoil and omg da muzzle blast !! ..... sometimes on a windless day, you can smell the stench as they try shooting their Queefmores without a can for the first time

 

[Jimvo]

Recoil is an inevitable consequence of a powerful firearm. For young guys, its an annoyance. For those of us beyond the Biblical "three score and ten" who take bruise friendly blood thinners, its a bit more concerning - especially if we like to shoot, shoot, shoot.

 

[Canadian Bushman]

Load a 30-06 and a 308 to similar velocities with the same powder and bullet.

Do the same thing with a 300 win mag and the wsm.

They have a different "feel"

 

[Jimvo]

Do the weapons have the same mass, the same geometry, the same operating principle? "Felt" recoil is much more complicated than case design. There is just no theory of physics (that I know) that can explain how the shape of the case can affect recoil. I get a lot more recoil from my 357 revolver than my 45ACP, but on the calculator the 45 should "kick" more.

 

[Swamplord]