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technique
10-05-2009, 6:17 PM
Alright, I'll start with the scenario:

The nearest visible road behind my house is 330 yards. The average speed of vehicles traveling on that road is 55mph.
With say 5.56 62gr. Wolf FMJ's...a 14.5in, 1/7 twist, and a x4 ACOG.....how much lead would I need to make hits on a vehicle? 2-4ft. lead if there is little to no wind?

And now to the disclaimer:

I would never shoot at a moving vehicle with innocent people inside of it. I am just curious. New surroundings is all, and I'm just judging distances and what have you.


Thanks.


Or maybe I should just say "thanks Randall!";)

Spyder
10-05-2009, 6:20 PM
Sounds like a dangerous question to throw out on a public forum...even with the disclaimer! :D

bbguns44
10-05-2009, 6:24 PM
That's a 8th grade math question. Pretty simple. Go back to school
if you can't work that out. & show your work.

technique
10-05-2009, 6:27 PM
That's a 8th grade math question. Pretty simple. Go back to school
if you can't work that out. & show your work.

Well if your so ****ing smart, answer it! :rolleyes:

Besides you are lacking what velocity/FPS 62gr. Wolf travels at.....thats why I'm asking.

mif_slim
10-05-2009, 6:29 PM
About 2.5-2.7 feet out with the 14.5" barrel. Wait, nevermind. LOL I didnt add the 55mph. Im too lazy today, just got out from a surgery.

AngelDecoys
10-05-2009, 6:29 PM
Been years since i did physics. To be accurate, you're going to need the angle of approach on the road. If the road is coming straight at you, you won't need to lead.

Tweak338
10-05-2009, 6:31 PM
LoL, Tech is already trying to figure out how to deal with situations in SHTF scenario.

I have no clue. What area of said vehicle are you trying to hit?

MT1
10-05-2009, 6:34 PM
31 foot lead if my math is right

Forgot to add that this is for .308 @ 2600fps

technique
10-05-2009, 6:34 PM
There is no angle....its left to right like the circus duck shooting game.

technique
10-05-2009, 6:35 PM
LoL, Tech is already trying to figure out how to deal with situations in SHTF scenario.

I have no clue. What area of said vehicle are you trying to hit?

Engine...Cab...I don't think it would matter in terms of lead.

civilsnake
10-05-2009, 6:38 PM
If you know the velocity of the bullet and the distance to travel, then you know how long it will take to get there.

Once you have that time and the velocity of the moving vehicle, you'll know how far the vehicle will travel given that set time.

You need to lead by that much.

technique
10-05-2009, 6:38 PM
About 2.5-2.7 feet out with the 14.5" barrel. Wait, nevermind. LOL I didnt add the 55mph. Im too lazy today, just got out from a surgery.

I'm at a loss in figuring it out....If I don't know how fast the bullet is traveling.
I was hoping someone would have some software for that.

FullMetalJacket
10-05-2009, 6:39 PM
Okay, let's see...

330 yards * (3 feet/yard) = 990 feet.

According to this site (http://www.angelfire.com/art/enchanter/bullet.html) the approximate time of flight to 330 yards for M855 is 0.35 seconds (about halfway between 300 and 350 yards).

How far does a vehicle move at 55 miles per hour in .35 seconds?

55 miles/hour * (hour / 3600s) * (5280 ft/mile) * 0.35s = about 28.2 feet.

Desert_AIP
10-05-2009, 6:41 PM
Where's Randall and that link to his Appleseed shoot?

Fjold
10-05-2009, 6:42 PM
The 62 grain load is right near 3,000 fps
The car is travelling 80.667 fps
330 yards is 990 feet
The bullet will take .33 seconds to reach the car

The car will travel 26.62 feet in .33 seconds



JBM says that it take .423 seconds for a generic FMJ to travel 330 yards at a muzzle velocity of 3,000fps

So the car will travel 34.32 feet in that time.

technique
10-05-2009, 6:44 PM
cool, I book marked that site..... :thumbsup:

sevensix2x51
10-05-2009, 6:44 PM
i thought thats why we had our chinese takeover parts kits. so we can figure this all out using the kentucky windage method... can you reliably disable a vehicle's engine with 223? i think .308 would be a better round for said scenario. :D

MT1
10-05-2009, 6:45 PM
The 62 grain load is right near 3,000 fps
The car is travelling 80.667 fps
330 yards is 990 feet
The bullet will take .33 seconds to reach the car

The car will travel 26.62 feet in .33 seconds

You didn't take negative acceleration into account like FMJ and I had in our numbers.(known flight time) = lower number for you.

AngelDecoys
10-05-2009, 6:45 PM
Once you think you have it figured out, buy an old oil drum and have someone brave tow it behind a truck using a VERY long rope. You can test your math.

mif_slim
10-05-2009, 6:45 PM
I'm at a loss in figuring it out....If I don't know how fast the bullet is traveling.
I was hoping someone would have some software for that.

Oh well Wolf usually travels at about 3001 average from my 24" barrel. So, given that its a 14" barrel, about ~50fps per inch off would make it about 2500-2600fps. This is because my 16" with the same ammo is getting avrge of 2760fps.

NRAhighpowershooter
10-05-2009, 6:45 PM
use tracers and walk them into the moving target........;)

FullMetalJacket
10-05-2009, 6:45 PM
Y'all who are taking the distance and dividing by the muzzle velocity to get the flight time are going to wind up understating the lead, for two reasons:

1) The bullet slows with distance. It is not still travelling at muzzle velocity out at 300 yards.

2) The path of the bullet is not linear, but parabolic.

FullMetalJacket
10-05-2009, 6:46 PM
You didn't take negative acceleration into account like FMJ and I had in our numbers.(known flight time) = lower number for you.
My brotha from anotha motha!

;)

technique
10-05-2009, 6:46 PM
use tracers and walk them into the moving target........;)

I can have those now!!!:D

nicoroshi
10-05-2009, 6:47 PM
Assuming the bullet speed is an average of 2750fps over the 330 yards distance traveled. that would be 916 1/3 yards/sec so that would get the bullet to the target (330yards) in about 2.78seconds [EDIT] ARGH!!! other way .36seconds.

Car travels 55mph.
mile= 5280ft/ph
60 minutes in an hour
60 seconds in a minute
3600 seconds in an hour

so car travels 5280 ft in 3600 seconds or 1.467 ft/sec [EDIT] ARGH! *that by 55 so it's 80.685ft/sec
Or
[EDITED ANSWER]
80.685* .36seconds= 29.057 ft of car travel in .36seconds.

If my tired head did the math correctly then. ( I am tired, and screwed it up the first time)
Lead the car by about 29 feet give or take a few inches [hypothetically of course]. :P

gunn
10-05-2009, 6:47 PM
bbguns is right. It is an 8th grade math problem.
I'll help you do it.

1) Find out the muzzle velocity of this ammo out of your barrel. Google is your friend here.
http://www.thefiringline.com/forums/showthread.php?t=74761
I used 2500FPS for my calculations just to make things easy. If the bullet goes faster, the goal of what you want to calculate is lower.
- If you want to get fancy here, you can derive an equation using the 3 datapoints given above to figure out the. IIRC (engineering school was a while ago), this is a fourier transform.

2) Calculate the time required for a bullet to travel the straight distance (330yds) from you to the vehicle @ t=0. This is simple math and unit conversion.

3) Convert the vehicle's speed into FPS.

4) Calculate the distance the car would have travelled in feet from t=0 to t=bullet going straight has hit the road.

5) You now have two distances: the straight distance if the bullet flew straight and the distance the car traveled. Tangent of the # of degrees of lead-in (aka the degree you are looking for) = (the distance the car traveled / the distance the bullet traveled if you were aiming straight at the car at t=0). Simple trig here.

In the interest of making this interesting for you, solve it yourself.

And who said math isn't useful (besides letting you get a job that pays for toys)?

-g

Fjold
10-05-2009, 6:48 PM
You didn't take negative acceleration into account like FMJ and I had in our numbers.(known flight time) = lower number for you.

Corrected it with JBM's time of flight calculation.

Fjold
10-05-2009, 6:51 PM
Assuming the bullet speed is an average of 2750fps over the 330 yards distance traveled. that would be 916 1/3 yards/sec so that would get the bullet to the target (330yards) in about 2.78 seconds.

Car travels 55mph.
mile= 5280ft/ph
60 minutes in an hour
60 seconds in a minute
3600 seconds in an hour

so car travels 5280 ft in 3600 seconds or 1.467 ft/sec
Or
1.467ft/sec * 2.78seconds= 4.075ft of car travel in 2.78seconds.

If my tired head did the math correctly then.
Lead the car by about 4 feet give or take a few inches [hypothetically of course]. :P


Your solution (in bold above) has the car driving at one MPH.

It should be 55 * 5280/3600 = 80.666666667 fps

Technical Ted
10-05-2009, 6:53 PM
How fast and what direction is the wind blowing at any given distance?

GrizzlyGuy
10-05-2009, 6:56 PM
See here:

http://www.snipercountry.com/HotTips/MovingTargets.htm

nicoroshi
10-05-2009, 6:58 PM
Your solution (in bold above) has the car driving at one MPH.

It should be 55 * 5280/3600 = 80.666666667 fps


Agreed, and corrected with edit above


i am tired.

technique
10-05-2009, 6:59 PM
How fast and what direction is the wind blowing at any given distance?

Its calm now....But since that 330yards belongs to me:D...I plan on putting some flags out.

The only thing I was lacking was bullet travel time, I have seen various people using different tools for that. So I figured I would see what everyone had to say....We obviously have some different answers going on in here.

supermario
10-05-2009, 7:10 PM
Hey Technique, i see you changed your location already.. Thats cool, gonna be nice with all the weapons huh!;)

technique
10-05-2009, 7:24 PM
Yup.....

I see you decided to keep your LMT. If you wanna swoop that kit anyway, let me know. I posted it on 1 site already (no real traffic there though)

Tweak338
10-05-2009, 7:30 PM
So when are you going to come back and visit us?

technique
10-05-2009, 7:37 PM
So when are you going to come back and visit us?

At some point I suppose. But man it sure is fun here. I went to a place called RK Gunsmithing today and had a little fun. Checked out some cool little cans and listed weapons. Got a few mag release springs and buttons.:)

Bigballaizm
10-05-2009, 7:44 PM
All I can say is... It must be nice!! Take care my brother!

Tweak338
10-05-2009, 7:50 PM
At some point I suppose. But man it sure is fun here. I went to a place called RK Gunsmithing today and had a little fun. Checked out some cool little cans and listed weapons. Got a few mag release springs and buttons.:)
Your getting spoiled out there!

johnrunner89
10-05-2009, 10:26 PM
Shooting at moving targets always seemed like a cool thing. I enjoy to shooting clays but wouldn't dare to try it with a rifle. I recently had an idea of sticking a long stick with an empty milk/juice/water gallon on top and mounting it on a remote control car and have someone drive it around while I try to shoot it. From different distances and different speeds it would be challenging. It would probably have to be done in the desert since no range would allow it, the remote control car user would be standing beside me or a little behind and the car would have to be infront of a good backstop but it seems like it would be safe and fun to try. Just an idea to add to my list...

Flying Bones
10-06-2009, 6:49 AM
Don't worry about it tech, you live in the middle of a small valley deep within the potato state. You're going to be fine out there.

ar15barrels
10-06-2009, 9:37 AM
The nearest visible road behind my house is 330 yards. The average speed of vehicles traveling on that road is 55mph.
With say 5.56 62gr. Wolf FMJ's...a 14.5in, 1/7 twist, and a x4 ACOG.....how much lead would I need to make hits on a vehicle? 2-4ft. lead if there is little to no wind?

I can't find a 62gr bullet similar to what wolf uses so I went with a 55gr bullet at about 3000fps which is about what you get with a 14.5" barrel with M193.
With no wind consideration and the target moving 90 degrees to your position, you need to lead 33ft.

Phil3
10-06-2009, 9:41 AM
http://www.jbmballistics.com/~jbm/cgi-bin/jbmtraj-5.0.cgi

This will answer it.

- Phil

Joe788
10-06-2009, 12:19 PM
This reticle (http://en.wikipedia.org/wiki/Heckler_&_Koch_G36) has lead marks for 8kmh at 200m, which I guess would be a running soldier? I could have sworn I saw a reticle somewhere for shooting at faster moving vehicles.

1. Point of aim at 200 meters range
2. Lead mark for firing at targets moving from left to right at a speed of approx. 8 km/h at a range of 200 meters
3. Circular reticule (Interior diameter 1.75 m man size at 400 m range)
4. Lead mark for firing at targets moving from right to left at a speed of approx. 8 km/h at a range of 200 meters
5. Horizontal line to determine whether the weapon is canted from the horizontal
6. Point of aim for firing at approx. 400 meter range
7. Point of aim for firing at. 600 meter range
8. Point of aim for firing at. 800 meter range
9. Man size of 1.75 meters at range X (200, 400, 600, 800m)



http://upload.wikimedia.org/wikipedia/commons/a/a1/G36Reticle.png

technique
10-06-2009, 12:22 PM
See, I think if I upgraded to a TA31RCO instead of the TA31F....I would be set.

ar15barrels
10-06-2009, 12:50 PM
See, I think if I upgraded to a TA31RCO instead of the TA31F....I would be set.

It would be easier to just set a remote triggeried IED on the side of the road. ;)

JTecalo
10-06-2009, 12:56 PM
It would be easier to just set a remote triggeried IED on the side of the road. ;)

:eek: you are just BAD!! :D

technique
10-06-2009, 1:02 PM
It would be easier to just set a remote triggeried IED on the side of the road. ;)

That might even be legal here:D J/K

ar15barrels
10-06-2009, 1:02 PM
:eek: you are just BAD!! :D

What?
He's got a fixed kill zone.
A minefield would work too.

RugerNo1
10-06-2009, 1:04 PM
What?
He's got a fixed kill zone.
A minefield would work too.

This!:43: That way you can save some ammo...

Technical Ted
10-06-2009, 1:16 PM
What?
He's got a fixed kill zone.
A minefield would work too.
IED

Scratch705
10-06-2009, 1:22 PM
Shooting at moving targets always seemed like a cool thing. I enjoy to shooting clays but wouldn't dare to try it with a rifle. I recently had an idea of sticking a long stick with an empty milk/juice/water gallon on top and mounting it on a remote control car and have someone drive it around while I try to shoot it. From different distances and different speeds it would be challenging. It would probably have to be done in the desert since no range would allow it, the remote control car user would be standing beside me or a little behind and the car would have to be infront of a good backstop but it seems like it would be safe and fun to try. Just an idea to add to my list...

use ballons, so you don't have to worry about hitting the r/c car. :)

ar15barrels
10-06-2009, 1:27 PM
We are building a moving target platform for the CaPRC club, but here's me shooting one in las vegas:

BJ9pZCuaYhE

Ishoot
10-06-2009, 1:39 PM
Thanks for the class fellas. :)

MasterYong
10-06-2009, 1:48 PM
This would be an absolutely EPIC Mythbusters episode.

Their experiments are typically fatally flawed, but it's still be sweet, especially since the rifle they always use is Jaime's M1 Garand.