Modern sporting rifles on the Moon?

[Mesatchornug]

Far more than that, as the arc of the bullet would be a smooth parabola as there would be no aerodynamic drag.


The producers actually apologized for that afterwards, saying they should have researched it


Yes


It would be effectively the same.


While the air inside the case contributes effectively nothing to the powder burn, as the oxidizer is already in the powder. a better questions is will the 15 psia inside the case unseat the bullet the first time the round is exposed to vacuum?

You're talking about a pound or less of pressure on the back of that projectile. That shouldn't be a risk if it's crimped at all.

 

[Glockster30]

Get a projectile to move at 2.38 km/s (~7,809 fps) and it will exceed the escape velocity of the moon and travel forever.

 

[AHM]

With 1/6 gravity, that red triangle would have you covered all the way out to 1800m. You'd only start getting into the hash marks at nearly two and a half klicks, and I'm sure not shooting that far.

At that range, the target might well be able to just hop out of the way after he knows you've fired. Because remember, your leaps and jumps on the moon are a lot more effortless and go a lot farther. And it's not like he'd need to hop very far to avoid your measly MSR bullet.

Far more than that, as the arc of the bullet would be a smooth parabola as there would be no aerodynamic drag.

Hold those thoughts.

 

[hpm]

Get a projectile to move at 2.38 km/s (~7,809 fps) and it will exceed the escape velocity of the moon and travel forever.

And all future moon landings would have to factor in the risk of a sudden bullet coming at them...and returning every 76.44 minutes.

 

[rali]

It’s all irrelevant. Maura published a letter in the Globe and anyone on the moon with an MSR is actually a felon-in-waiting. NASA will be an unindicted coconspirator.

(What? Someone had to post it ...)

 

[KBCraig]

Obligatory most epic underwater battle scene:


View: https://m.youtube.com/watch?v=Z3my3VW6vXw

That's the most unrealistic battle scene since John Wayne's "The Green Berets".

 

[Roy Rogers]

No sound in space so no ear protection or suppressor needed, just come as you are in your space suit?

 

[OnTheRoad]

It would be effectively the same.

But would it though? remember, your own weight would be 1/6 of usual and the recoil energy would be the same. So instead of having a 180 pound foundation wouldn't you have a 30 pound foundation with the same recoil energy pushing against it...

 

[rali]

But would it though? remember, your own weight would be 1/6 of usual and the recoil energy would be the same. So instead of having a 180 pound foundation wouldn't you have a 30 pound foundation with the same recoil energy pushing against it...

Not really. See previous posts about weight related to mass. Weight is the local way to express mass. On earth they’re the same, but on the moon, your weight changes, but not your mass. F=ma and none of those change based on local gravity, so your felt recoil is exactly the same.

(edited because “your” and “you’re” are not interchangeable... can I blame autocorrect?)

 

[Prepper]

Would the bullet spin properly and point forward, or would it tumble? It would have no air rushing past the sides of the cone shape.

I'm guessing it would not tumble.

 

[Broc]

Obligatory most epic underwater battle scene:


View: https://m.youtube.com/watch?v=Z3my3VW6vXw

Wow, I have never seen that one before. That was so epic. They even had different uniforms.

 

[Picton]

Would the bullet spin properly and point forward, or would it tumble? It would have no air rushing past the sides of the cone shape.

I'm guessing it would not tumble.

I think it wouldn't matter whether it was spinning or not. Wouldn't it just keep on going in the direction it was already going until lunar gravity acts on it?

I think lunar gravity would be the ONLY variable affecting it once it left the muzzle, regardless of its shape and its degree of spin...

 

[xtry51]

We only spin bullets to stabilize them. It is unlikely you could fully stabilize a bullet in space due to there being an unpredictable, uneven force acting on the bullet by the gasses as it exits the barrel. Most bullets wouod tumble. But unlike on Earth this would not effect their path of travel due to their being no air.

 

[AHM]

... Weight is the local way to express mass. On earth they’re the same, but on the moon, you’re weight changes, but not your mass. F=ma and none of those change based on local gravity, so your felt recoil is exactly the same.

Felt recoil would be the same,
but you'd be 6x as likely to skid backwards from the recoil
compared to if you were on Earth standing on a pile of moon dust, wearing moon boots.

Spoiler: ETA: Moon boots

 

[Prepper]

I think it wouldn't matter whether it was spinning or not. Wouldn't it just keep on going in the direction it was already going until lunar gravity acts on it?

I think lunar gravity would be the ONLY variable affecting it once it left the muzzle, regardless of its shape and its degree of spin...

I would expect identical trajectory either way. The tumbling will only matter in impact as it varies how the damage happens. Although, it only has to get through a space suit.

 

[fitzknny]

You guys are all thinking about gravity, oxygen and atmospheric pressure.

My first thought is, "how am I going to get my fat space suit finger in the trigger guard?

Modified trigger system to a squeeze action on a elongated pistol grip . . . maybe ?

 

[AHM]

Modified trigger system to a squeeze action on a elongated pistol grip . . . maybe ?

How about a crank you turn?
No?

 

[fitzknny]

How about a crank you turn?
No?

Hmmmm. . . might throw off aiming in a rapid fire mode . . . but the possibilities are endless.

 

[Toast]

But would it though? remember, your own weight would be 1/6 of usual and the recoil energy would be the same. So instead of having a 180 pound foundation wouldn't you have a 30 pound foundation with the same recoil energy pushing against it...

No. Your body will still mass 180 pounds with regards to the recoil. It will only be exerting 30 pounds of weight on your feet.

Unlike SI, where kg is used for mass and newtons for force, English unit use lbm (pound-mass) for mass and lbf (pound-force) for force, both of which are colloquially shortened to "pound".

 

[AHM]

Unlike SI, where kg is used for mass and newtons for force, English unit use lbm (pound-mass) for mass ...

I'm a traditionalist - I use the slug.

 

[OnTheRoad]

No. Your body will still mass 180 pounds with regards to the recoil. It will only be exerting 30 pounds of weight on your feet.

Unlike SI, where kg is used for mass and newtons for force, English unit use lbm (pound-mass) for mass and lbf (pound-force) for force, both of which are colloquially shortened to "pound".

My strengths lie in places other than math and physics. Either way good to go shooting on the moon, won't get recoiled into orbit, just be careful of sliding backwards in my space boots.