.223 ft/lbs at 100 yards.. how to calculate?

[Burnsy87]

I'm math dumb, so forgive me.  I have a few AR's I don't necessarily want to use for deer - coyotes are another matter - but I'd just like to know how to calculate that number we need to hit.

[HuskerXDM]

Quick google search this one has a calculator
http://www.pyramydair.com/article/What_is_Muzzle_Energy_August_2003/5
I know it's for air guns but plug in bullet weight and velocity

[Burnsy87]

I don't know actual velocity out of different barrel lengths though.

[jonm]

chrony is the right way or Google will get you close.

[tstuart34]

Factory or reloaded ammo?

[DR4NRA]

I don't know actual velocity out of different barrel lengths though.

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]

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

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.

[Burnsy87]

Exactly what I'm saying.  I don't like long barrel AR's.  I got a basic 16" and an SBR.

[jonm]

you aren't going to get there with a 223 sbr. invest in a different caliber. an 8" 300blk or a short 6.8 spc will make the necessary power.

[DR4NRA]

300 Whisper is a good round. Seen good things lately at the 300 yard line out of the 6.8.

[Burnsy87]

Eh I don't have the time for reloading and I don't want to pay that much for ammo.. I shoot my firearms a lot, cheap plinkin ammo is high on my 'importance' list.

[JAK]

Take a look at the 7.62 x 39 AR's.  When you are just blasting use the cheap FMJ and for hunting use the Hornady SST loads.

John K

[RobertH]

My 16" 223 upper got 930-ish ft\lbs when i chronied it with 55gr hornady amax.

[Burnsy87]

I'm a TSX guy, got some 50 and 70 gr.. 70gr quotes 2800 out of a 20" barrel

[RobertH]

I'm a TSX guy, got some 50 and 70 gr.. 70gr quotes 2800 out of a 20" barrel

I forgot to mention my rounds are factory loaded, also the box says 3240fps. If you know your velocity and bulet weight you should be able to calculate it.

[Burnsy87]

55gr good enough for larger game?

[RobertH]

55gr good enough for larger game?

Its legal yes, but is it best? Prolly not. Spot placement is key. And no long shots.