Maximum Effective Range 5.56 vs 7.62x39

[Loosedhorse]

What does "effective" mean?

The maximum range at whch a user can be expected to place one on a man-sized target? Or the maximum range at which it can still cause a casualty?

The Army said (somewhere) that 58 ft-lb of energy is needed in a projectile to cause a casualty on an unarmored target.

A 62-gr. bullet must be going at least 650 fps for that; a 123 gr bullet, over 460 fps.

I can't find ballistics tables that go out far enough to tell me at what distances these bullets slow to these speeds. Suffice it to say, the bullets for both guns remain lethal well past the distance at which they can be accurately aimed (by most shooters).

 

[floorit76]

Kinda reminds me of the 17hmr, 22wmr debate. A small fast flatter round vs. a larger heavier slower round. Your more likely to hit it with one, but more likely to kill with the other. If you are comfortable with your ability to lob the heavier round onto targets at long ranges go for it. But to be effective you first have to hit the target.

 

[mshootnit]

Once I sat down with an Arsenal milled 7.62X39 16" barrel carbine. At open sights with typical wolf ammo 123 gr 2360 fps, I started banging away at a buffalo sillouette which was out there at 500 yds. At that range the bullets I recovered were opened up and mushroomed to back to about 33% of their length, and they made an audible BANG. At that range. I think obviously still lethal at 500 yds.

 

[GlockFu]

Thanks for everyone's input. It sounds like 5.56 is the way to go since I am definitely not good enough to lob my bullets into a target. Next question...

What would be the best weight bullet and twist rate for this same goal with a 20 inch barrel?

 

[Robert]

I like my 1:7 barrel. I use mainly 55 and 62gr bullets but could go up to 77gr or even 80s if I wanted to. Some people seem to think that a 1:7 will over spin 55gr bullets but I have never had an issue. Some of the very, very light might have issues.

 

[Z-Michigan]

Best bullets are the 77gr Sierra Matchking, 77gr Nosler match HP, and 75gr Hornady BTHP. (The Hornady 75gr AMAX would seem like a good choice but apparently can't be loaded to an AR15 magazine length.) Those are all similar high quality bullets with high BC's for a .224 bullet, and can be loaded to work with an AR15.

You can buy commercial ammo using these from Black Hills, Hornady, and some others. I think Federal has a 77gr BTHP load but it may not be quite as hot as the others.

You want a 1/7 or 1/8 twist for those bullets.

If you are stuck with a 1/9 twist barrel, some will shoot the 75-77gr bullets above and some won't. If yours won't, the 68-69gr BTHP bullets from Sierra and Hornady are your best bet. Black Hills, Remington, and I think Federal offer loaded ammo with those bullets.

 

[Ignition Override]

Glock Fu:
A friend and coworker retired from the NAVRES on the Navy Marks. Team.

As for rifle/shooter potential, I knew him for a while before learning that he set an AR record, at both 200 and 600 yards. Have no idea whether it was with his Bushmaster, the match bullet weight(s) or 'rifling ratio'.
He won over a dozen M-1 Garands (one being a Navy M-1), among other gun prizes.

 

[my762buzz]

Another consideration:

2 American manufactured loads

150 grain 7.62x39 loads with an exit velocity of 2300fps
at 750 yards 1110 fps and 411 ft pounds of energy

125 grain 7.62x39 loads with an exit velocity of 2400 fps
at 725 yards 1100 fps and 336 ft pounds

 

[henschman]

If you're comparing apples to apples and looking at the standard surplus ball ammo that both caliber rifles end up shooting most of the time, the 5.56 is easier to hit with out past 300m because it has a flatter trajectory and doesn't tend to tumble as soon. Whether it is actually "effective" once it hits the target at the farther distances is another matter... it gets most of its "effectiveness" from bullet fragmentation, which generally doesn't happen past 150m on a 14.5" carbine or 300m on a 20" rifle. I suppose it's pretty much the same for the 7.62x39 once it loses enough energy, out past 300m or so... except it's just punching a little .3" hole.

With hand loads and different bullet types, you can effectively reach out to a lot farther distances with both calibers.

 

[proven]

henschman, are you saying that an m4 "generally" isn't effective past 150 yds?

 

[henschman]

No, I'm saying standard surplus ball ammo generally doesn't fragment in a "soft" target after that distance. Whether punching a .22" hole through the target is "effective" enough for your purposes would depend on the application.

 

[C-grunt]

Even if the round doesnt fragment they still will usually yaw wich increases wounding significantly. Either rifle isnt going to be hugely effective out past 300 yards but it still will put a hole through you.

 

[my762buzz]

it gets most of its "effectiveness" from bullet fragmentation, which generally doesn't happen past 150m on a 14.5" carbine or 300m on a 20" rifle.

Out of a 20 inch barrel, M193 reaches the lowest tumble threshhold at 2500 fps at 200 yards.

 

[Z-Michigan]

2 American manufactured loads

150 grain 7.62x39 loads with an exit velocity of 2300fps
at 750 yards 1110 fps and 411 ft pounds of energy

125 grain 7.62x39 loads with an exit velocity of 2400 fps
at 725 yards 1100 fps and 336 ft pounds

What are these loads and who makes them? The distance to 1100fps suggests much higher BC's than I'm used to seeing for x39 bullets, and the starting velocity for the 150gr is higher than anything I've seen before for 7.62x39.

 

[my762buzz]

What are these loads and who makes them? The distance to 1100fps suggests much higher BC's than I'm used to seeing for x39 bullets, and the starting velocity for the 150gr is higher than anything I've seen before for 7.62x39.

Corbon readthe exterior ballistics tab on each page

http://www.shopcorbon.com/CORBON-Hunter/7.62x39-150gr-CORBON-Hunter-JSP/HT762X39150-20/300/Product


http://www.shopcorbon.com/Self-Defe...N-Self-Defense-JHP/SD762X39125-20/100/Product

 

[Z-Michigan]

Thanks. I ran their numbers through a ballistic calculator and they appear to be consistent. HOWEVER, I think it should be noted that the exterior ballistics they are claiming need to be considered based on their test altitude - 3450ft for the 150gr and 3300ft for the 125gr. That makes the long distance performance look dramatically better than it would be at sea level, where most people make comparisons. I realize they are in South Dakota at roughly those elevations, so that ammo may perform as stated at their home range and for anyone using it at the same or higher altitude, but ALL ammo will show greater long distance numbers if you calculate its ballistics at 3450ft instead of at sea level. At sea level both loads lose almost 100 yards of supersonic range, and of course their drop at any given distance becomes a bit greater as well. They are also listing a 20" barrel for the 150gr and 18.5" for the 125gr, while most people evaluate 7.62x39mm based on the most common 16" barrels - but at least they aren't doing the 24" SAAMI test barrel game that most other companies do, so some credit is owed.

 

[Z-Michigan]

Incidentally, a 5.56 Mk262 type round (77gr at about 2750fps) would still be at 1116fps at 1000 yards if you calculate it at 3450ft altitude. Go up to 8000ft altitude like you might see in the 'stans and it's retaining 1268fps at 1000 yards.

 

[Beck]

The problem with the 7.62 x 39 isn't the round per se, but the the firearms chambered for it and the poor design of most cheaply had ammo made for it. Ever since I bought a Ruger Mini-30 in 1989 I've been a fan of the 7.62 x 39 through extensive testing and research. Back then I could only find one decent bolt gun chambered for it... a Sako with 20-inch barrel. There are a few more bolt guns chambered for the x39 out there now and I'm interested in acquiring one again.

My Mini-30 is all tricked out and about as accurate a Mini as you'll find, but the round can do better in a serious bolt action with a longer barrel... and good ammo. One of my fav loads is a 122 gr hollow point by Hanson. With the Mini-30 I can hit well within an 8-inch plate all day at 300 yards with lethal velocity. And I can do better than that with a decent boat tail round or something like the 125 gr green-tip Nosler spitzer rounds once loaded into x39 brass by Darrell's Shooting Supply out of Illinois. I love my Mini, but if I'm going to try to hit anything 400 yards and beyond it's not going to be with the Mini, and certainly no SKS or AK. But imagine what a good load can do in a stable bolt action with longer, heavier barrel that would do this caliber justice. Then you're closer to a fair comparison of these two rounds.

Regards

 

[JShirley]

IIRC, the M16 has an Army-described effective range of 550 meters, and an M4, 500 meters.

I'd call the 7.62x39 350 meters.

John

 

[meanmrmustard]

Are we talking effective range to kill, maim, or paper punch?

556- I've used it on deer up to and including 188 yards, pass through.
7.62x39- 125 yards, through and through. No farther shots available.

Paper punching can be done however far you'd like, just gotta hit stuff.

As for use against evil doers: I was always told that, in some cases it was better to wound the enemy than to kill. Wounding takes several of your enemies off the field, unless of course they leave their wounded to bleed.

 

[JShirley]

some cases it was better to wound the enemy than to kill. Wounding takes several of your enemies off the field, unless of course they leave their wounded to bleed

The first known instance of this explanation was some years after the 5.56x45mm was fielded, fwiw.

John

 

[winfried]

223

Hi All, I follow threads here at random. Not sure what you people call "effective range".
At 500m 7.62x39 has a Vel of 363m/s and a kinetic energy of about 53mkg a flight time of .992seconds, mid range trajectory elevation is about 1207mm and will penetrate about 2.9mm of mild steel.
The .223 at 500 has a velocity 485m/s, a kinetic energy of 42mkg, a flight time .73seconds a maximum elevation of 654mm and will penetrate about 3.7mm mild steel.
These 7.62x39 values are for East German ammo with copper plated steel jacket bullet and olive greeb laquared steel cases with velocity variations of between 706 and 711m/s which is excellent.

Russion ammo (steel jacket and steel case both copper plated) are about 20m/s faster
but lesst consitant.

Czech ammo was the fastest (of similar appearance as the russian)with about 40m/s faster than the East German type, but much less consistant.

Yougoslav ammo with brass cases has no boat tail and is for long distance the worst and to be avoided for another reason.

Regards

WAH

 

[winfried]

Hi John, no that outlook that a wounded soldier takes three soldiers out of combat to look after him goes back at least to 1870 and possibly much earlier.

Regards

WAH

 

[meanmrmustard]

The first known instance of this explanation was some years after the 5.56x45mm was fielded, fwiw.

John

Oh yeah? Didn't know that...

It makes sense, the theory of it, and I would think that thought would have crossed soldiers minds since projectile weaponry had been used.

 

[JShirley]

Not sure what you people call "effective range"

In my case, "you people" (that phrase is usually associated with pejorative comments in the USA, btw) are United States military sources. As I said previously.

The US Army says the M16A2-4 has a maximum range of 3600 meters. Effective range against a point target in these rifles is 550 meters, and against an area target (troop concentration, for example) is 800 meters. Understanding the description makes it clear that the US military believes the projective is dangerous to at least 800 meters, but that, in currently fielded rifles, hitting an individual (enemy combatant) target past 550 meters is unlikely.
Here's the table in question from FM 3.22-9.