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.223 ft/lbs at 100 yards.. how to calculate?
DR4NRA:
--- Quote from: Burnsy87 on December 29, 2014, 09:02:12 AM ---I don't know actual velocity out of different barrel lengths though.
--- End quote ---
WAG time.
Use the velocity from your manual and guesstimate using loss of roughly 35 to 50 FPS for each inch of tube shorter. A chrony will be a lot more useful.
SemperFiGuy:
First, set up a chrony @ 100 yards.
Second, shoot a round through the chrony's measuring area to obtain the bullet's velocity. [Should be No Biggie to cleanly hit through the chrony throat area with a .223 @ 100 yards.]
Third, calculate the kinetic energy.
Using the English system,
Square the velocity. [=velocity "squared"]
Multiply [velocity "squared"] by the bullet weight in grains/7000
Divide by 32
Result will be ft-lb of energy at 100 yards. (Must be at least 900 ft-lbs to be legal in NE for deer. Usta say "factory ammo only"; FWIW, no longer so says.)
Or just post your 100-yard velocity in ft./sec. right here on the Forum and we'll crank out the ME for you.
Important Rules:
1. Do Not Shoot the Chrony.
2. Do Not Loan Your Chrony to a Bad Shooter.
3. If You Do Loan Your Chrony, Get Some Kind of Tangible Cash Security First.
sfg
DR4NRA:
--- Quote from: SemperFiGuy on December 29, 2014, 03:21:47 PM ---First, set up a chrony @ 100 yards.
Second, shoot a round through the chrony's measuring area to obtain the bullet's velocity. [Should be No Biggie to cleanly hit through the chrony throat area with a .223 @ 100 yards.]
Third, calculate the kinetic energy.
Using the English system,
Square the velocity. [=velocity "squared"]
Multiply [velocity "squared"] by the bullet weight in grains/7000
Divide by 64
Result will be ft-lb of energy at 100 yards. (Must be at least 900 ft-lbs to be legal in NE for deer. Usta say "factory ammo only"; FWIW, no longer so says.)
Or just post your 100-yard velocity in ft./sec. right here on the Forum and we'll crank out the ME for you.
Important Rules:
1. Do Not Shoot the Chrony.
2. Do Not Loan Your Chrony to a Bad Shooter.
3. If You Do Loan Your Chrony, Get Some Kind of Tangible Security First.
sfg
--- End quote ---
Laffin big time here. Your drops will be all wrong as most if not all ballistics charts run off muzzle velocity measured 10 feet from the muzzle.
OP if you want shoot me a PM and if you want to come to lincoln I will take you out to Ike's and set up my Oehler and calculate drops and energy before you go home.
FarmerRick:
From here: http://www.winchester.com/Products/rifle-ammunition/Performance/Super-X-rifle/Pages/X223R2.aspx
Winchester 64gr. SuperX power point. Most commonly accepted ammo as being suitable and legal for deer in Nebraska.
RIFLE BALLISTICS
DISTANCE(YDS) VELOCITY(FPS) ENERGY(FT.LBS.) TRAJ.SHORT TRAJ.LONG
Muzzle 3020 1296
50 0.1-0.2
100 2656 1003 0 1.7
200 2320 765 -3.5 0
300 2009 574 -13.4 -8.2
400 1724 423 -32.1 -25.1
500 1473 308 -53.6
This should give you a general idea of what kind of muzzle velocity you'll need in order to get a certain muzzle energy farther downrange.
DR4NRA:
You aren't gonna get 3020 w/64 gr bullet out of a short AR, that's the ballistics from winny w/24 inch tube.
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