Bullet Drop of .223 and .308 Discussion.

[EricCartmann]

Not trying to get into too much detail (such as FPS, barrel length, bullet weight, ballistic coeffecient, temperature, altitude, humidity, or rifle type). Not going for precision, just need a general idea where things stand.

So say you just pick up a .308 and .223 and start blasting down range. On average what do you think the bullet drop will be?

Here is a Chart I came up with:

.308

100yards Zero
200 -5" (as in negative 5 inches from POA(point of aim) at 100 yard zero).
300 -15
400 -35
500 -65
600 -110
700 -160
800 -240



.223

100yards Zero
200 -3" inches
300 -10
400 -25
500 -50
600 -75
700 -115
800 -170

What do you think of this chart? Is it inline with what you are getting with your particuliar rifle, your particuliar barrel length, and your particuliar bullet weight?

[Stockton]

This ballistic program (online & free) will give you a pretty close chart for anyone's rifle.

http://www.eskimo.com/~jbm/ballistics/traj/traj.html

[glockman19]

Temperature, Wind, Elevation, Humidity, Angle will all change the BDC.

IMHO unless in competition you will not need to take a shot at more than 200 yards in Defensive situations or 400 yards in Hunting situations.

[EricCartmann]

glockman, just curious if those bullets were out of a particuliar rifle and barrel length, or are those just the general numbers you have for all your rifles?

[jandmtv]

barrel length and bullet type matters alot!

[Prc329]

Here is an example. I had a load developed using 45.5g of RL14 behind a 155g Scenar load for my Savage with a 1-10 twist barrel and 24" long. The same load in my 700 with a 22.25" barrel and a 1-12 twist ran 2800 fps. It took almost a grain to get the velocities up. This changed my drop table by a bit. My 500 yard come ups is 9.5 minutes for my load running at 2900 fps. The load running at 2800 was 10.25 minutes.

That would be the difference from a hit to a miss. 1 MOA is roughly 5 in at 500 yards so I would have been off almost 4 in.

[rksimple]

barrel length and bullet type matters alot!

More than most realize. Different bullets behave very differently. Start at the JBM site and play around a bit.

[Prc329]

Here is a quick table for federal gold medal 168g ammo. Assuming optimal conditions and sea level.

MOA valuse

50 -.25
100 0
200 2.25
300 5.25
400 8.75
500 12.50
600 17.00

[rksimple]

Not trying to get into too much detail (such as FPS, barrel length, bullet weight, ballistic coeffecient, temperature, altitude, humidity, or rifle type). Not going for precision, just need a general idea where things stand.

Thats like saying, "Not to get into detail about engine size, weight, etc...how fast does a car go?"

There are too many variables for a general idea.

[aplinker]

The .223 ammo I used yesterday shot 1.3 mils lower than the one I used last week.

Both were 55gr FMJ.

Same rifle and nearly identical conditions.

Convert that to moa and inches at 600yds and you'll see how much of a difference it makes.

[EricCartmann]

I know but in general you can say Cars go about 120 mph for top speed. This is what I am trying to figure out here.

I have found that with my chart it comes very close, and you will only have to make little adjustments for rifle type, barrel length, and rifle type.

I agree with what you guys say about it makes a huge difference between bullet type (such as boat tail), weight, and barrel length. But like I said, I am just trying to find a very rough average number.

Also, I was thinking more in line with the BDC on ACOGs calibrated for .308. I wonder what barrel length, and ammo was used for the .308 ACOG? I believe the .223 ACOG BDC on a NSN is calibrated for a 55gr bullet out of a 14.5" barrel. And my TA11F is for a 55 gr bullet out of a 16" barrel.

For .223 I have found that M855 or M193, both are almost dead center out to 300 yards, at most there will be a 4" difference at the extremes of high and low.

[Prc329]

1 mil is 3.6 inch at 100 yards if I recall.

[ar15barrels]

The .223 ammo I used yesterday shot 1.3 mils lower than the one I used last week.

1.3 mils at 600 only due to weather?
That's like 27" or so.

[EricCartmann]

Here is a quick table for federal gold medal 168g ammo. Assuming optimal conditions and sea level.

MOA valuse

50 -.25
100 0
200 2.25
300 5.25
400 8.75
500 12.50
600 17.00

I shot this past weekend 40 rounds of Federal Gold Medal Match and found those numbers in line for what I did with my 22" M1A, clear day, about 70 degrees, no humidity and about 2500 ft above sea level.

[Prc329]

Also, I was thinking more in line with the BDC on ACOGs calibrated for .308. I wonder what barrel length, and ammo was used for the .308 ACOG? I believe the .223 ACOG BDC on a NSN is calibrated for a 55gr bullet out of a 14.5" barrel. And my TA11F is for a 55 gr bullet out of a 16" barrel.

For .223 I have found that M855 or M193, it is only about a 4" difference out to 300 yards.

Pure speculation but I believe they use an M14 to determine BDC.