best rifle for the moon

[B.L.E.]

There was a sci-fi story about this. The Russians established a moon base across from where we had planted out flag, so we built a moon base. Then tensions escalated and both sides opened up on each other. The bases were basically made of aluminum and plastic so they were easily perforated. Both sides declared a cease fire and began to patch up their moon bases.

The bullets have enough energy to make several thousand low-level orbits around the moon, so, every few hours they have to re-patch where the bullets re-puncture the structures, and the bullets just keep going round and round the moon.

But as we know - that wouldn't happen in real life.

I ran the numbers, taking the moon's equatorial gravity at 1.622 m/sec^2 and the mean equatorial radius at 1,738.14 km and that works out to having to shoot a bullet 5576 fps to achieve a low orbit.
I don't think you would have to worry about any normal gun putting a bullet into orbit.

 

[kraigwy]

Civilian LE Bomb Techs go to Huntsville, Redstone Arsenal FBI/USArmy Hazardous Device School.

It's called Hazardous Device School as oppose to Bomb Disposal because civilian LE deals mostly with Hazardous Devices, or home made bombs, (now called IED) more then conventional bombs or military explosives.

Part of their job is disposal of explosives, chemicals, GUNPOWDER, and other hazardous materials. They are trained in hazardous devices, in how they are made, and how they are taken apart, to include what they are made of.

I was such a bomb tech or hazardous device technician for the Anchorage Police Department for over 16 years, during that time, in either training or disposal of material, I did in fact use blasting caps (several times) to ignite smokeless powder and it did in fact go High Order.

Bomb Techs do indeed have to know DOT as well as Hazmat Regulations.

Redstone Redstone Arsenal Hazardous Course 8-8-83

 

[brickeyee]

I did in fact use blasting caps (several times) to ignite smokeless powder and it did in fact go High Order.

Better tell DOT their flammable solid shipping test test is wrong then.

When i was working on a commercial license for blasting and explosives we repeated the DOT test numerous times (on some very large cartons of surplus powder) and never had a single grain of powder ignite.

It made a nice mess on the range area, but we just use a weed torch ti burn it all off.

We also tested a number of 'home made' bombs, including very high speed photography of the containers to determine exactly what was going on.

Black powder produced VERY different behavior than smokeless, but still nothing compared to he higher energy compounds we had available.

Shaped charge work was very interesting, including repeatedly cutting off one and two foot sections of a large i-beam driven vertically into the ground.

 

[raftman]

The Russian gun was to be used to fend off wolves and such after landing from what I've read.

Yep.

In the very early days, Russian cosmonauts (including cosmonaut #1 Yuri Gagarin) were issued a Makarov pistol for space flights. Later their space program switched over to the combo rifle Glenn mentioned. In both cases, the weapon was intended for use on Earth as a wilderness survival tool upon returning from space (if say, the landing was significantly off-target for whatever reason).

 

[teeroux]

AR-15?

I ran the numbers, taking the moon's equatorial gravity at 1.622 m/sec^2 and the mean equatorial radius at 1,738.14 km and that works out to having to shoot a bullet 5576 fps to achieve a low orbit.
I don't think you would have to worry about any normal gun putting a bullet into orbit.

You forget that the f/s of rifle rounds may very well be below 5576 f/s on earth but the moon doesn't have an atmosphere or air resistance the only things affecting the bullet are the powder and gravity. Without atmospheric pressure I think there will be a significant increase in velocity of the bullet. Every time you fire your rifle in atmosphere that bullet first has to expend the energy to overcome 14.5psi or so of atmosphere.

Does anyone have a formula or data on bullets in vacuum vs atmosphere?

 

[10-96]

Either way, and mathematical equationing aside- I think handguns would be the most logical platform (man I hate that word) to begin studying. My reason for that is simple- has anybody seen any pics of gunracks in the back windows of spaceships?

 

[Sport45]

Every time you fire your rifle in atmosphere that bullet first has to expend the energy to overcome 14.5psi or so of atmosphere.

Does anyone have a formula or data on bullets in vacuum vs atmosphere?

14.7 psi on the nose of a 30 caliber bullet exerts a whopping 1lb of pressure. Take that away and the 40-60,000psi or so you have behind the bullet won't know the difference. The muzzle velocity on the moon won't be measurably different from the muzzle velocity on earth. Assuming of course, the firearm is operated at approximately the same temperature as here on earth. Daytime and nighttime temperature swings could make a difference with the powder burn characteristics...

Don't use heavy oil or graphite to lube the thing.

 

[Nnobby45]

I'd say a .22 so you don't fly back 50 feet every time you pull the trigger.

Don't be silly. If you can't use a rifle for propulsion--- what good is it?

But FIRST, we have to settle a potential problem.

Since there's no oxygen on the moon---would the powder even burn?

 

[Sport45]

Since there's no oxygen on the moon---would the powder even burn?

Absolutely. Didn't you read the posts in this thread?

The real question is does it burn, explode, deflagrate, or decompose.

 

[B.L.E.]

Yes, the chemicals used in gunpowder contain their own oxygen. Besides, there is no significant amount of oxygen inside a cartridge, especially with a compressed load of powder.
Explosive bolts are used to separate stages of rockets, they have no problems exploding in outer space.
Depth charges and torpedos have no problem exploding under water.

Taking nitroglycerine for an example, 227 pounds of nitroglycerine contains 144 pounds of oxygen, 36 pounds of carbon, 42 pounds of nitrogen, and 5 pounds of hydrogen.

 

[Brian Pfleuger]

You forget that the f/s of rifle rounds may very well be below 5576 f/s on earth but the moon doesn't have an atmosphere or air resistance the only things affecting the bullet are the powder and gravity. Without atmospheric pressure I think there will be a significant increase in velocity of the bullet. Every time you fire your rifle in atmosphere that bullet first has to expend the energy to overcome 14.5psi or so of atmosphere.

Yeah, the formula is easy. A bullet, let's say Sport45's .308 caliber, has an area (Area of circle = pi(r)^2) of 3.1415926x(.154^2)=.0745 sq inches. 14.7psi times .0745 sq inches equals 1.09 pounds of force. If we assume 55,000 psi in the cartridge, the force is 4,097 pounds. The absence of that 1 pound makes no difference.

If we accept 5,576 f/s as the orbital velocity at the equator, a fast rifle cartridge would go a long, long ways before it hit the ground. I load a 22-250 round at 4,435 fps. That's just shy of 80% of orbital speed.

I can't find a calculator that does exactly what I want.... but I did find one that does moon trajectories....
A bullet fired at 4,435 fps FROM GROUND LEVEL at a 10dg angle would travel 237 miles and reach a height of 11 miles. Even a measly 1200 fps would reach 17 miles at a 10dg angle.
Fired straight up at 4,435fps, it would reach an altitude of almost 685 miles and takes 27 minutes to come back down.

 

[B.L.E.]

Since there is no air for the bullet to travel through, there is absolutely no disadvantage to shooting a light for the caliber bullet. You could even shoot spherical plastic bullets out of a smoothbore and that might possibly get you up to lunar low orbit velocity. With no atmosphere, the benefits of rifled barrels would be moot.

There is a velocity barrier with smokeless powder. At some point, the powder uses up all its energy to accelerate itself out of the barrel. Even at 4000 fps, the powder charge begins to outweigh the bullet it propels and a point of diminishing returns comes into play. A rifle can shoot a bullet no faster than the gasses of a high pressure blank can travel.

 

[Brian Pfleuger]

Max velocity with typical gunpowder is very close to lunar orbit speed (5,500 fps). Actually achieving that speed is a lot harder. I suspect that ultralight plastic bullets might get you close.

 

[smoakingun]

Some of you guys really put a lot of thought into this. I have reviewed the pretinent information revealed in these posts and have come to a conclusion, given the generous tolerences of the ak 47 and its reputation for reliability in conditions where even stngle shot rifles fail, I must declare the ak47 to the perfect moon rifle!

 

[wogpotter]

Digressing for a moment here.
I do not have the perfect moon gun, but I do have the perfect moon target!
It involves a Koala & if I posted it here this thread would be locked so fast our ears would pop.

 

[Single Six]

Peetzakilla: Congrats; amid all of these other posts on this thread that went completely over my head, your 9:33 AM post from today is the hands down winner! To be honest, this whole discussion blew completely past my meager math / science skills pretty early on, and I'm still not sure who to believe. Oh, well...I'll keep reading anyhow, maybe I'll learn something.

 

[Single Six]

Peetzakilla: P.S.: That was intended as a compliment, by the way!

 

[Brian Pfleuger]

Keyboard equations looks more complicated than they really are!

 

[jimbob86]

With all those bullets reaching low orbital velocity..... a few firefights on the moon surface would maroon the Loonies in short order, caged in a high velocity lead prison, no?

Mehbee that's why they took the fight to Earth with the mass driver and big rocks.....

 

[gyvel]

So many geeky answers... The only weapon needed is a revolver chambered in 45ACP (no rifle needed). Can anyone tell me why?

Well... Why?