This is how to calculate remaining velocity!

[Boberama]

Here is a link to the complete tables ( how to calculate ) :

http://sites.google.com/site/remainingvelocity/

As a note, if you wanted to print that out, it might take 30 pages!

I personally wrote out the number for every 50fps on a page of lined paper.
On the back I wrote out the time figure for every 50 fps.

The instructions tell you how to interpolate the velocities in between each 50 fps.

I found this quite useful. Go to the Federal website and try any load. Find the ballistic coefficient for the bullet and see how accurate it is!

Tell me what you think.

 

[R.W.Dale]

I just use my iPhone ballistic app.

I input the load (factory or handload) and it tells me all this info in less than a second

 

[Boberama]

Yes, you could do that. But I refuse to carry cellphones etc ( don't ask, tinfoil hats were at a discount this week ) and because I don't always have access to a computer, but I do always have access to pen and paper. Just think it might be useful to some people.

 

[R.W.Dale]

you should make a slide rule!

Why you'd sell a million of em

 

[Yo Mama]

Thanks for the link Boberama, nice information.

 

[Boberama]

Krochus, I actually do have some slide rules. I don't use them much though.

 

[R.W.Dale]

Krochus, I actually do have some slide rules. I don't use them much though.

LOL I'm young enough to only have seen a couple in my lifetime. one came with a lee powder dipper set I used to use

 

[sumpnz]

Point Blank is a pretty good program for this. You can get all kinds of ballistics data calculated and output in 5-100 yard increments. It will give you wind drift as well as time of flight and leads on moving targets of various speeds.

 

[Boberama]

OK, the reason I found this out was so I didn't have to use a ballistics program.

I like doing stuff the old fashioned way. At least as old fashioned as scienific calculators.

 

[Boberama]

No takers?

 

[Mr_Pale_Horse]

I wrote an exterior ballistics program while working for the Navy in the 80's. I still use it on occasion (it lacks a GUI), since it allows you to use variable Ballistic Coefficient, because BC's are a function of velocity. However, the variation is not that great at hunting ranges. It is if concern out beyond 400 yards.

 

[MCMXI]

BC's are a function of velocity. However, the variation is not that great at hunting ranges. It is if concern out beyond 400 yards.

Tell me about it!! I was reminded of that while shooting LaRue 12" (W) x 18" (H) reactive targets at 800 yards several weeks ago. Sierra lists multiple BC's for their bullets. For example, the 175gr MatchKing (SD = 0.265) has the following BC's listed:

.505 @ 2800 fps and above
.496 between 2800 and 1800 fps
.485 @ 1800 fps and below

However, I shoot Hornady's excellent 178gr A-MAX with a listed BC of 0.495 and an SD of 0.268. Hornady only provides a single BC value which may be an average BC over "typical" .308 velocities based on "typical" ranges. I say this because my data suggests that the BC is closer to 0.520 at 2,700 fps.

 

[Welding Rod]

Here is what I use: http://www.appliedballisticsllc.com/index_files/MOBALL.htm

 

[ClayInTX]

All those tables are good for only approximation.

Empirical formulas are the same.

Windage affects a bullet but the bullet does not move sideways at the crosswind speed because it’s not in the crosswind long enough to match it. The mass and shape of the bullet also affect the crosswind component.

Air density affects the bullet. Humid air is less dense than dry.

Temperature affects the bullet. Hot air is less dense than cool.

Altitude affects the bullet. High altitude air is less dense than sea level.

Gradient affects the bullet. Up hill and down hill does not drop in relation to line of bore as much as level.

Are they making a Cray laptop these days?

 

[MCMXI]

Air density affects the bullet. Humid air is less dense than dry.

Humidity has a negligible affect on air density since the difference in mass of dry air and 100% RH air is negligible. You only need to "worry" about elevation, atmospheric pressure and temperature. Those three values are neatly wrapped up in one parameter called DENSITY ALTITUDE.

 

[Uncle Mike]

Dense, or cold air is good for airplane wings, normally aspirated engines, but bad for bullets.

All things being equal....Hypothetically, a bullet sighted in at 100y will drop 58" on a 60 degree day but only drop 56" on a 90 degree day.

Warm air....less dense, less air molecules in a given space, more water molecules.
Less air molecules for the bullet to move through, less drag on the bullet, the bullet fly's farther and flatter.

The same can be said of barometric pressure.....HIGH barometric pressure...MORE air molecules in a given space, bullet has more air molecules to travel through, more drag on the bullet, bullet doesn't fly as far or as flat.

LOW Barometric Pressure..... LESS air molecules in a give space, bullet has less air molecules to move through, less drag on the bullet, bullet fly's farther and flatter.

Elevation.... HIGH Elevation, less Barometric pressure, LESS, air molecules per given space, LESS air molecules for the bullet to move through, less drag on bullet, bullet flys farther and flatter.

LOW Elevation.... MORE air pressure, more air molecules per given space, more air molecules for bullet to move through, more drag on bullet, bullet doesn't fly as far or as flat.

So, let's recap: Assuming you're sighted in and dead on at 100y. at a certain atmosphere, then, things change,it gets:
HOT(er)>>>> Bullet will hit HIGH(er) at 100y
COLD(er)>>>> Bullet will hit LOW(er) at 100y.

Your dead on at 100y and the Barometric Pressure:
INCREASES(High Pressure)>>>> Bullet will hit LOW(er) at 100y
DECREASES(Low Pressure)>>>> Bullet will hit HIGH(er) at 100y

Your dead on at 100y and you: (Above Sea Level)
INCREASE your Elevation>>>> Bullet will hit HIGH(er) at 100y
DECREASE your Elevation>>>> Bullet will hit LOW(er) at 100y
This meaning you, the shooter increases or decreases your elevation in regards to mean sea level, nothing to do with your sights on the firearm.

 

[Boberama]

The thing is, you can't carry a computer with you everywhere, unless it's a laptop. And cell phones are a definite no-no. I can't stand them.

Quote from Jason Peter's The Final Word on Cell Phones

What is it about this repellent little gadget that so abominates, that so offends the imagination?

It has destroyed manners. It has destroyed public space. It has compromised privacy. It has enslaved and mastered those who think themselves its master. It has transferred money from insurance companies to body shops. It has turned b|tching into a spectator sport, and I won’t be at all surprised if it turns out to be the cause of an epidemic of brain tumors.

That pretty much sums up my position on the mobile phone. Or iPod.

 

[R.W.Dale]

What you mean the device I'm posting this from makes calls too??? Aside from being a shot timer, ballistics computer, auto trouble code refrence, alarm clock, a map, measurments converter, accelerometer, speedometer, weather radio, flashlight, television, pc, notebook, scientific calculator, game caller and recording device

you know rewind to the popular wisdom of 90 years and the exact same thing could be said about the automobile aka "devils chariot" A device that single handedly done more to morally bankrupt this country than the smart phone ever will

 

[five.five-six]

Yes, you could do that. But I refuse to carry cellphones etc

meh, you just need one of these