Does anyone have the formula, or a link to a web page that has it, which can determine down range foot pound energy of a projectile based on the "at the muzzle" velocity measurements? I have done a couple of searches of the Forum and can't didn't find this one. Interested in extrapulating energy and velocity of round balls at 50 and 100 yrds. without having to set up a chronograph at those ranges (and risk blowing it apart with a thrown shot!)
-
Friends, our 2nd Amendment rights are always under attack and the NRA has been a constant for decades in helping fight that fight.
We have partnered with the NRA to offer you a discount on membership and Muzzleloading Forum gets a small percentage too of each membership, so you are supporting both the NRA and us.
Use this link to sign up please; https://membership.nra.org/recruiters/join/XR045103
Foot Pound Calculations @ Distance
- Thread starter jdixon
- Start date
Help Support Muzzleloading Forum:
Yes, I have the 2d ed. of the Lyman book here. It gives a good base line of stats. But, it is limited in its information. Many of the stats deal with in-line guns and sabotted projectiles. Also, none of the tests are done with premium powders such as Swiss or Goex Express, which is what I use. Also the barrel lengths that I have (a pistol with a 16 1/2" in .50 1:18 twist and a Tenn. Mtn. rifle 36" in .50) are not listed though some come close. Part of the fun is knowing exactly, or as close as possible, what your front stuffer is doing, that is why I am looking for the mathematical formal to calculate this information. Thanks for the suggestion though.
Sully:
Yup, that looks like what I am looking for. Takes a little bit to figure out how to use it. Ran some calculations and they seem to follow (+/-10%) those that appear in the Lyman book. Still would like to know that actual formula - save me from carrying the lap top to the shooting table. Thanks for the link. Yes, this needs to be on the resources page!
Yup, that looks like what I am looking for. Takes a little bit to figure out how to use it. Ran some calculations and they seem to follow (+/-10%) those that appear in the Lyman book. Still would like to know that actual formula - save me from carrying the lap top to the shooting table. Thanks for the link. Yes, this needs to be on the resources page!
Everyone is sort of focused on foot/pounds but remember the projectile plays a role as well, you are dealing with soft lead that expands rapidly and has a lot of surface area compared to a long, skinny bullet. Makes a difference in hunting.
longcruise
70 Cal.
If you plan to use the popular FPE formulas to decide how effective your rb loads are, then simply reconcile yourself to limiting your shots to 15 or 20 yards. That way your FPE figures will match up with the popular notions of how much fpe it takes to kill such and such animal!
Or, you can simply rely on your own experience or the experience of other hunters and see that the fpe measure of killing power means nothing to a rb and probably not to modern projectiles either.
just my abrasive .02 cents worht :winking:
Or, you can simply rely on your own experience or the experience of other hunters and see that the fpe measure of killing power means nothing to a rb and probably not to modern projectiles either.
just my abrasive .02 cents worht :winking:
J.R. said:
Hey J.R., here is another version for you. Hopefully it is not too late to be of use to you:
[url] http://www.norma.cc/htm_files/javapagee.htm[/url]
Before you can put this thing to use, you need to pull out your calculator and do some figuring. First, you need to know the weight of your bullet. If you are using a roundball, you can get an approximate number by using:
weight in grains =1502.6 x (Diameter x Diameter x Diameter)
As an example using a 0.570 ball of lead, that would be 1502.6 x (0.57 x 0.57 x 0.57) = 1502.6 x 0.185193 = about 278 grains.
Now get the ballistic coefficient using:
BC = Ball Wt. in grains divided by (10640 x diameter x diameter)
Again using a 0.570 roundball as an example we have 278 / (10640 x 0.57 x 0.57) = 278 / 3456.936 = 0.0804
Now back to the on-line ballistics table at the end of the link posted above. Over on the left side, at the bottom, click on the "ok" button next to the label that says "Define your own bullet." That opens up some spots where you plug in the bullet weight and its coefficient. Click the "ok" button there, then take a look over on the right side.
Use your mouse to drag the red lines around to set the muzzle velocity and other parameters, and move the long red line on the range scale to see bullet rise or drop at that range, velocity and energy at that range, etc.
Enjoy!
Last edited by a moderator:
