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Posted: 5/1/2002 5:57:57 PM EDT
I ran some numbers on a ballistics program, and it does not appear that there is as big a difference at long range between these two rounds as I thought. Are my results correct? I kind of hope so, because I would much rather put together a SPR type AR-15 than switch over to a 700, M1A, AR-10, or FAL for longer ranges.

I compared two Sierra BTHPs, 69 grain and 168 grain, as loaded by Federal. While you can put heavier bullets in both cartridges, I thought this would be a good comparison because these seem to be popular match bullet weights. At 1,000 yards, with a 200 yard zero, the 223 drops 415” and the 308 drops 402”. So there is no significant difference as far as bullet drop.

In regards to wind resistance, with a 10mph crosswind the 223 is moved 41” at 600 yards and 140” at 1,000 yards, and the 308 is moved 34” and 112”. So while there is a difference here, 21% and 26% respectively, it is not earth shattering. You might need to be a little better judge of the wind with the 223, but your skill in this regard will need to be well developed with either cartridge.

The 308 has a clear advantage as far as energy, but at 1,000 yards the 223 still has more energy than a 22LR at the muzzle. So while I doubt you will knock a guy off his feet at long range with the 223, he is probably not going to keep coming either.

And yes, I am ignoring cover. But I figure you need to see what you can hit.

Am I up in the night here?
Link Posted: 5/2/2002 8:06:48 AM EDT
You going to get the 7.62 NATO guys pissy.

Some will say Bullet size is a moot point, more so when your talking handgun cartridges, but for some reason when you talk about rifle cartridges, people get really defensive.



Link Posted: 5/2/2002 8:25:52 AM EDT
And the 223 looks even better w/ a 77SMK moly, moving ~2850fps as in my 24" CR6724 zeroed at 100 yards, the round drops ~355" at 1000 yards.

At 600 yards w/same rifle/zero, drop is 76.5"

Mike
Link Posted: 5/2/2002 8:31:33 AM EDT

The 308 has a clear advantage as far as energy


Per Federal Cartridge at 500 yards

223 rem = 215 ft-lbs
308 win = 1230 ft-lbs


You decide....

Link Posted: 5/2/2002 10:11:36 AM EDT
Just getting hit with a bullet is always a bad thing, but what happens next is largely related to energy. The short version: What ECS said. Watch-Six
Link Posted: 5/2/2002 10:16:57 AM EDT
The .223 has nowhere near the velocity at that distance necessary to fragment, so it's lost one of it's most devastating features. 7.62 makes a bigger hole. I'd go with that for long-distance work.
Link Posted: 5/2/2002 10:18:56 AM EDT
Will the .223 remain stable at those distances? I seem to recall hearing somewhere that it would start to tumble after about 800 yards I believe. I dont really know, just a thought.
Link Posted: 5/2/2002 10:40:53 AM EDT
My real world experience is that the .308 is better for long distance accuracy. There can be a lot of varibility in wind over the greater distance. Though I think the .223 can be a very good round out to 600 yds., the .308 is easier to manage at that distance.
Link Posted: 5/2/2002 10:46:18 AM EDT

Originally Posted By garheadjr:
Will the .223 remain stable at those distances? I seem to recall hearing somewhere that it would start to tumble after about 800 yards I believe. I dont really know, just a thought.



Can't speak for anything other than the 77SMK moly loads we shoot out of the CR6724s, but they don't tumble. They go sub-sonic just short of a 1000 yards but they'll get there w/MOA accuracy under good air conditions.

Mike
Link Posted: 5/2/2002 10:48:08 AM EDT

Originally Posted By garheadjr:
Will the .223 remain stable at those distances? I seem to recall hearing somewhere that it would start to tumble after about 800 yards I believe. I dont really know, just a thought.



I'm not really sure either, but their velocities are not all that much different, so I doubt the 223s instability would come from going subsonic earlier. Even at 1,000 yards, both rounds are still going over 1,000 fps.
Link Posted: 5/2/2002 11:00:01 AM EDT

Originally Posted By eswanson:
The .223 has nowhere near the velocity at that distance necessary to fragment, so it's lost one of it's most devastating features. 7.62 makes a bigger hole. I'd go with that for long-distance work.


No doubt the 7.62 would be more lethal, but even at 1,000 yards the 223 still has more energy than a 22LR at the muzzle. Yes, that is no show stopper, but think about how nervous you would get if some guy was pointing a 10/22 at you from five feet away. Think about if he shoots you once. You probably won't die right away unless he gets your CNS, but are you going to stick around? It still seems like it would be enough force to scare away or deter most opponents.

This is all academic for me, but the numbers were just not as different as I thought they would be.
Link Posted: 5/2/2002 11:19:39 AM EDT

Originally Posted By ECS:
Per Federal Cartridge at 500 yards

223 rem = 215 ft-lbs
308 win = 1230 ft-lbs


You decide....


I am not sure energy is all that important, but the 308 will certainly make a bigger hole. I am more concerned about how much flesh the 223 would penetrate. But I have never been able to find any information on this.

BTW, for the two cartridges I was talking about, here is an energy (ft/lbs) comparison:

Muzzle: 1380 (223) v. 2520 (308)
400 yards: 600 v. 1335
600 yards: 375 v. 940
1,000 yards: 165 v. 485

Still, if energy is your yardstick, the .223 is better than 45 ACP at 600 yards, but down to 32 or 38 special at 1,000. That's nothing to sneeze at.
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