Author Topic: Hypothetical ammo question  (Read 468 times)

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Offline miketx

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Hypothetical ammo question
« on: October 08, 2017, 07:56:29 AM »
I like to read and I read a lot. All kinds of stuff but mainly I like science fiction. I just finished reading an interesting book and in it an exploration team goes to explore an Earth like planet in the Epsilon Eridani system. It's well written, no two headed alien zorks trying to eat them or anything, just an exploration adventure. The planet is a little smaller than Earth and only has about 0.8 Earth gravity. One team is exploring an area and come across some wolf like hostile animals and the team is forced to defend themselves with gunfire. They are all military trained and they are all missing the targets! It finally dawned on the captain that the bullets were hitting high due to the lesser gravity. I thought about this and wondered how that would work, as it had never occurred to me before that in any travels of that nature if they ever become possible, could that be a factor in defensive firearms use? Any thoughts? If so I suppose one the first things you do on a new planet is go to the gun range!

Offline JohnnyDollar

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Re: Hypothetical ammo question
« Reply #1 on: October 08, 2017, 08:26:00 AM »
I would suspect that it depends on how far out the target is, the velocity of the bullet and the atmospheric density encountered.

But, all other things being equal,
an AR-15 shooting a 5.56 bullet with a 100yd zero here on earth generally rises .72 inch over 100yds.
so, 80% gravity would theoretically allow it to rise 20% higher, which would translate into about 5/32" (.144") higher impact at 100yds.

If aiming at center of mass, I doubt they would miss their targets.


« Last Edit: October 08, 2017, 10:06:25 AM by JohnnyDollar »
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Offline Tango

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Re: Hypothetical ammo question
« Reply #2 on: October 08, 2017, 08:33:37 AM »
.
oh, now I see why some here practice indirect fire with handguns   :th_nuts:
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Offline Shipwreck

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Re: Hypothetical ammo question
« Reply #3 on: October 08, 2017, 09:04:30 AM »
.
oh, now I see why some here practice indirect fire with handguns   :th_nuts:

Yes, it is all about gravity practice  :th_thicon_lol:

Offline DCD327

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Re: Hypothetical ammo question
« Reply #4 on: October 08, 2017, 07:18:28 PM »
.
oh, now I see why some here practice indirect fire with handguns   :th_nuts:

HEY,,,  ya NEVER know,,,,,   :th_thicon_idea:
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Offline Alte Schule

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Re: Hypothetical ammo question
« Reply #5 on: October 08, 2017, 10:41:37 PM »
When exploring new planets every one should know that the go to weapon should be a phase plasma rifle somewhere in the 30 watt range.  :th_thicon_funny:
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Offline DCD327

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Re: Hypothetical ammo question
« Reply #6 on: October 08, 2017, 10:51:25 PM »
When exploring new planets every one should know that the go to weapon should be a phase plasma rifle somewhere in the 30 watt range.  :th_thicon_funny:

Aint that the model Marvin Martian used on Bug Bunny?  :P
Politicians are like diapers, they should be changed often, and for the same reason.

There are two kinds of people in the world my friend. Those with loaded guns, and those who dig. YOU DIG.  " Blondie".

Well, any man that wouldnt cheat at cards for a poke, dont want one bad enough. " Gus".

Offline miketx

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Re: Hypothetical ammo question
« Reply #7 on: October 09, 2017, 08:43:30 AM »
When exploring new planets every one should know that the go to weapon should be a phase plasma rifle somewhere in the 30 watt range.  :th_thicon_funny:

Aint that the model Marvin Martian used on Bug Bunny?  :P

No, these were projectile weapons in a bullpup configuration.  But I like your thinking.

Offline mike609

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Re: Hypothetical ammo question
« Reply #8 on: October 09, 2017, 10:02:55 AM »
Gravity would be an issue with rifles at 400 yds or so.  Maybe 100 with pistol rounds. 


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Offline noylj

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Re: Hypothetical ammo question
« Reply #9 on: October 15, 2017, 07:32:00 PM »
Just remember, the bullet doesn't go up--the barrel is pointing up.
If the barrel was perfectly level, than at sea level, the bullet would drop at 32.2 ft/s^2. At 80% gravity, it would drop at 25.8 ft/s^2.
I think, if my match is at all correct, at a height of 5 feet, a bullet fired (or anything dropped) exactly parallel to the ground would take (minus friction in air) about 0.56 seconds at sea level on Earth and about 0.62 seconds on the EE planet.
Some one want to do the ballistic calculations.