Ballistics question.


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slash415
May 1, 2012, 01:09 AM
So I was reading a few articles that stated that the maximum range (non effective) for a 30-06 was around 4000 to 5000 yards. I also read that the .50BMG has a max range (non effective) to 6000 to 7000 yards. Now judging by the energy,size and the bullet BC, it seems like a .50 should go much farther. And for the 30-06, 6000 yards is only like 3.4 miles. Well my .22 is advertised at having the ability to shoot 2.5 miles. A.22lr is dwarfed by the size of a 30-06.

I notice this same thing with effective range also. A .308 with the right gun and ammo has the potential to be somewhat effective at 1500 yards. Well most people advertise the .50 bmg as having a range of 1500-2000 yards. If you compare a .308 and .50 bmg the size difference is massive! you would think a .50bmg would have a much farther range. However, I wonder sometimes if we really don't know the full potential of a caliber in certain circumstances. For example, like I said the .50 is advertised as having an effective range of 1500-2000 yards. However, the longest confirmed kill with that round is out past 2600 yards. Same thing with the .308. Advertised at 800 yards, but holding a record kill of around 1700 yards!

Maybe I just don't understand ballistics all that well.

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MachIVshooter
May 1, 2012, 03:25 AM
It's going to depend on load, bullet and weapon firing it, but those numbers aren't too far off.

jmr40
May 1, 2012, 08:13 AM
Maybe I just don't understand ballistics all that well.

Or you need to find another source for your information.

A rounds maximum range can be determined with a fair amount of accuracy. factors such as the angle it is fired, temperature, humidity, altitude all play a role. There is not as much difference in actul range between rounds so a 22 will come closer to a 30-06 than many realise. Same with a 50 BMG. The rules of gravity still apply and they will fall back to earth.

Effective range is really more guessing than science, but heavier, longer, more aerodynamic bullets maintain speed and energy longer and are more effective at greater ranges. The extreme long range hits with the 50 and 308 are probably farther than would be considered reasonable for the rounds.

I'm more familiar with 308 ballistics so I'll use it as an example. A 308 goes subsonic at just over 1000 yards. Making hits beyond that range becomes as much luck as skill. Having enough energy to get adequate penetation at those ranges is getting doubtful. Were talking around 700 ft lbs of energy at 800 yards and 500 ft lbs at 1000. That is probably the reason someone put the 800 yard effective range tag on a 308. At 1700 yards I'd just have to make a wild guess as to energy, but it has to be under 200 ft lbs, maybe less than 100 ft lbs. Even if you make a hit at that range, killing something, or someone starts to be more luck than skill.

x_wrench
May 1, 2012, 08:13 AM
i think effective is more of a term of what the known certain stopping power of the cartridge is, rather than, well, maybe it can, type of a thing. if that makes sense. kind of like saying your v8 pick up truck WILL tow a trailer of up to 5000 pounds, but under the right circumstances it MAY tow 9000. if they stated 9000, people would hook onto a 9000 pound trailer, and try to drag it up the steepest grade they could find.

epijunkie67
May 1, 2012, 09:20 AM
Physics says all objects fall at the same rate in a vacuum. On good ol' planet earth we have all that air to deal with which tends to slow down things like bullets. But as a general rule bullets will all fall straight down at about the same rate. Put another way, two different bullets will drop about the same distance over the same period of time.

Faster bullets will travel farther in a given period of time. That means they have less time to drop. And THAT means they shoot "flatter".

And when things fall to the ground they don't just fall at a constant speed. They accelerate. So in the first .25 second they fall a certain distance (we will call it X). The distance they fall in the next .25 second will be more (some distance >X).

So as our bullet is flying down range it is slowing down (spending more time to travel less distance) AND it is accelerating towards the ground at an ever increasing rate. This explains why ballistics tables show bullet drop increasing getting bigger and bigger over similar distances. Like 1" drop at 100 yards, 3" drop at 200 yards, 12 inch drop at 300 yards, etc.

So eventually all bullets are going to be dropping several feet over the distance of 100-200 yards if they get far enough out. Regardless of if it's a .22 or a .50 cal. It's just a question of how fast they are moving when they leave the barrel (muzzle velocity) and how quickly they slow down over a certain distance (ballistic coefficient).

adelbridge
May 1, 2012, 09:31 AM
But as a general rule bullets will all fall straight down at about the same rate. Put another way, two different bullets will drop about the same distance over the same period of time.

This is true. Set your gun up on the bench so the bore is level and the muzzle at 3 feet off the ground. drop a 150 grain .308 diameter bullet out of your hand from three feet and time it to the ground. Now shoot the same .308 from three feet. The bullet will hit the ground in the same amount of time.

303tom
May 1, 2012, 09:56 AM
http://www.youtube.com/watch?v=D9wQVIEdKh8

C-grunt
May 1, 2012, 05:29 PM
I believe the longest confirmed kill with a .308 sniper rifle is about 1200 meters. The M60 and M240s probably have kills out past that range. I have personally shot my old M240 out to around 1500 meters and have friends that have shot them out past 2000 meters.

A 147 grn FMJ at 2000 meters might not be hitting with a ton of velocity but Id bet it would still go through you. Wound would probably be similar to a heavy .32 caliber handgun. It wouldnt be the most effective thing out there but wouldnt exactly be good for your health.

taliv
May 1, 2012, 05:56 PM
don't have the source handy, but iirc, max range on 50bmg ball ammo was supposed to be 7000 meters


if you have some free time, go to jbm ballistic calculator and see how far of a range you can type in. i've never tried it but i wonder if there's a point it won't go past. (maybe tweak your sight-over-bore to be something like a foot, and your zero range something like a few feet, to get the barrel pointed up?)

fireman 9731
May 1, 2012, 06:17 PM
Its just like old brain teaser for laws of physics... If you fire a bullet from your gun, and drop one onto the ground at the same time, from the same height, they will hit the ground at the same time. Crazy huh? Gravity is king.

taliv
May 1, 2012, 06:24 PM
if by "old" you mean 1589 (http://en.wikipedia.org/wiki/Galileo%27s_Leaning_Tower_of_Pisa_experiment), then yeah. not been much of a brain teaser lately :)

Art Eatman
May 1, 2012, 07:05 PM
My recollection of GI Ball M2 was for a max range of about 3,500 yards. Ball M1, the 172-grain boat-tail, was 5,100 yards.

All I remember from my .50s was that the effective range was around 3,500 yards. But that was fifty-seven years ago. :D

BullfrogKen
May 1, 2012, 07:39 PM
Those figures sound about right.

MachIVshooter
May 1, 2012, 08:14 PM
don't have the source handy, but iirc, max range on 50bmg ball ammo was supposed to be 7000 meters

Everything I've seen shows 5,500 to 7,500 meters, depending on the round

interlock
May 2, 2012, 05:27 AM
we are getting a little confused here i think. The rounds are used in both machine gun and rifle platforms. A machine gun on a tripod can be laid onto a target in the sustained fire role and give a beaten area. A bit like a small artillery piece. The bullets are still pretty deadly... but they are not accurately aimed shots. It is these that are the longer range examples given.

the single aimed shots give a shorter range.

so yeah, a GPMG on a tripod laid onto a target 5000 yards away might give effective fire on a beaten area at its maximum. But a sniper rifle using the same round might have an effective maximum of 1500 yards.

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