5.56 vs. 7.62x39

[7998]

The 7.62 bullet is designed to tumble once hitting something firm, like muscle.

Because of this tumbling, the wound cavity is erratic and very large. You might get hit in the shoulder and have the round exit your butt.

Are you sure about that? I always thought that was the design of the 5.45 and 5.56. I'm under the impression M43 7.62 over penetrates, you need to use M67 or HP or SP to open up the wounding effect

[Arrdy]

Are you sure about that? I always thought that was the design of the 5.45 and 5.56. I'm under the impression M43 7.62 over penetrates, you need to use M67 or HP or SP to open up the wounding effect

To get around the "no hollow point in war" clause, the russians have an empty cavity under the point of the bullet, so the copper jacket deflects and causes the tumble.

I've picked up some spent surplus rounds and they do what they're supposed to.

[daschnoz]

As others have asked - what do you plan to do?

The 7.62x39 gets a bad rap due to its use in the AK platform. The AK platform was not designed to be sub MOA. It was designed to be cheap to build and easy to use. The idea behind it was to place 100,000 of them into the hands of the (no so smart) infantry and have them throw a wall of lead at the enemy. The cartridge itself is not that bad for accuracy.

The US mindset is simply different than the Russian mindset with respect to infantry tactics.

WITH THAT SAID

There has been interest in finding a cartridge that could replace the 5.56 in the AR platform over the last 5 or so years. If you look at all of the proposed replacements, you seem to find the same thing - a 125gr (ish) pill at about 2300fps - 2400fps.

Hmmmmm, I think the Russians already designed that round.

If you're punching paper, 5.56 gets it done. For social work, I prefer a bigger hole.

[ungawa]

5.56, .30-06, .308, 7.62x39, and 5.45 - none of them were "designed to tumble" and none of them generally do. All spitzer shaped bullets yaw when they enter flesh or other bingham plastics or Newtonian fluids. They don't start rolling end over end in most cases. It is rumored that 5.45 was designed to upset earlier than it otherwise might. But, even if that rumor was true, it is not designed to tumble.



7.62x39 Ball Ammo

1. Cheaper - Actually, same price as 5.56 in steel case, but most people shoot 7.62x39 in steel case and most people shoot 5.56 brass case which costs more.

2. Better penetration against most targets at most ranges under about 400 yards. However, bonded soft point (BSP) 5.56 has similar and sometimes better penetration and better terminal balistics.

3. Better performance through barriers. Because 5.56 ball relies on velocity which is lost when passing through barriers. 7.62x39 is a slightly larger and longer bullet so when neither fragments or expands the 7.62x39 will be somewhat more effective. Also, the 7.62x39 is heavier so better penetration after passing through a barrier is also expected compared to 5.56.

7.62x39 generally also loses this edge and becomes equal with BSP 5.56 or 5.56 designed for barriers.

4. Better damage past 200 yards versus 5.56 ball. 5.56 ball is more deadly and provides superior damage under 200 yards because of fragmentation. Past that distance, 7.62x39 is slightly larger and longer so it makes a somewhat bigger hole.

5. With short barrels, nothing changes with 7.62x39 but superiority of 5.56 is reduced in range with every lost inch in barrel length. This can be overcome with BSP 5.56 or with hollow-point boat tail (match) 5.56 ammo.

6. 5.56 has flatter trajectory and better accuracy at all ranges.

Summary - for most people, 5.56 will be much more deadly under 200 yards with a 20" barrel and somewhat less damaging past that. Cut that down to 130 yards or so or even 50 yards with SBR barrel lengths. Can overcome with 5.56 HPBT ammo. For most people, 7.62x39 will have much better penetration against most targets at most ranges and better performance after passing through substantial barriers at most ranges. Can be overcome with 5.56 BSP ammo. 7.62x39 cheaper, 5.56 shoots flatter.

[bigedp51]

The standard British Enfield .303 Mk.7 bullet had a aluminum tip under the copper jacket, this made the bullet tail heavy and yaw sideways when it hit flesh. Even the most stable bullet will try to yaw when it hits because of the extremely high rpm the bullet is spinning. The design of the bullet and its rotational spin control how much the bullet will yaw.

At this time the Mk 262 round loaded with the Sierra 77-grain HPBT Match King bullet yaws and causes more damage than any other U.S. Military round.

[Valorius]

It depends on the use. If your looking to stop groundhogs go with the 5.56, anything bigger get something else. Can you use 5.56 to hunt deer?
Seriously .308 trumps all but that's not answering your question.

If I'm an urban or suburban Escape from New York scenario give me an AK in 7.62. It stops cars goes thru walls and doors etc.
If I'm in an open rural environment with long ranges give me an M1A.

Makes you wonder why every major military force has abandoned the .30 cal as it's primary armament if the AK 7.62mm is so great doesn't it?

Unless the AK 7.62mm round is not really that great, then it makes perfect sense.

The standard British Enfield .303 Mk.7 bullet had a aluminum tip under the copper jacket, this made the bullet tail heavy and yaw sideways when it hit flesh. Even the most stable bullet will try to yaw when it hits because of the extremely high rpm the bullet is spinning. The design of the bullet and its rotational spin control how much the bullet will yaw.

At this time the Mk 262 round loaded with the Sierra 77-grain HPBT Match King bullet yaws and causes more damage than any other U.S. Military round.

Not all spitzers will yaw. It has to have it's CG aft of the centerline of the bullet. The more unbalanced and longer the bullet, the faster it will yaw though. This is what makes the Mk77 so devastating even out of short barrel carbines. It exhibits fragmentation at velocities as low as 2100fps.

To get around the "no hollow point in war" clause, the russians have an empty cavity under the point of the bullet, so the copper jacket deflects and causes the tumble.

I've picked up some spent surplus rounds and they do what they're supposed to.

To get around the "no hollowpoint clause" the Russians replaced the 7.62mm with the 5.45mm....

Wound profiles of various 5.56mm, 7.62x39mm and 5.45mm rounds:




If anyone can find a round on that chart that is more significantly more devastating than US Mk262 Mod1 77gr 5.56mm OTM, please point it out to me.

[Asmodeus6]

Makes you wonder why every major military force has abandoned the .30 cal as it's primary armament if the AK 7.62mm is so great doesn't it?

Unless the AK 7.62mm round is not really that great, then it makes perfect sense.

I get that you are of the light and fast mindset. I think your choices have made that clear. I like fast hole punchers too. I understand and subscribe to the fragmentation damage of the 5.56 round in the right conditions. I have seen it with my own eyes with the right loads.

But if you look at all the recent offerings from serious people trying to increase the terminal effectiveness over a wider range of conditions with people wielding AR type rifles, every "solution" has not been another 5mm round. They are all closer to .30 cal again.

6.8 SPC
6.5 Grendel
.300 Black Out
etc etc etc

What do all of these rounds have in common? They are VERY similar to the 7.62x39mm in bullet weight and velocity. Many have specific advantages, or considerations factored in (Such as case length, diameter to fit in an AR magazine etc) But if you take all of these rounds and plot them out / weight and velocity. And plunk 7.62x39mm in the middle of that chart. You're going to find a discussion ending amount of similarities.

I'm not saying that 7.62x39mm is superior to 5.56 or even 5.45. But saying 5.56 is clearly superior to 7.62x39 is equally impossible to do if you are looking at ALL of the information.

Plain ol' 7.62x39mm FMJ - without witch craft bullets, or modern metallurgy has killed more people on earth than any other bullet/weapon in existence. Including nuclear weapons, missiles, tanks, and bombs.

Things that "don't work" don't hold such records. Just saying.

Both calibers are a compromise from 7.62x51mm. One leaning towards higher mass at the expense of speed, the other towards higher speed at the expense of mass. Good bullets exist for both calibers. Both cost a good deal more than the average going rate of the caliber. Both have subtle advantages over the other. Pick according to what you value more.

[Valorius]

All those calibers you mentioned are just the latest greatest attempt to reinvent the wheel.

Physics dictates that light and fast is 'superior', not me. Energy is squared with velocity, but only doubled with mass.

The fact is NO ONE in the first world uses 7.62mm anything as a primary issue weapon, nor have they in decades. And there is a reason for that. Actually, there are tons of indisputable reasons for that.

5.56mm and 5.45mm are superior military cartridges for general issue when compared to 7.62x39 or 7.62x51mm.

If for no other reason than you can carry way more 5.56mm for the same weight. That alone is a massive advantage for the small bore calibers. Lack of recoil- another huge, huge advantage. Flatter trajectory- again another huge advantage. Vastly superior armor penetration- again, huge advantage.

And in the damage dep't, the right 5.56mm rounds do every bit as much damage as any 7.62x39mm round does.

7.62mm is obsolete as a primary issue caliber. And it has been for decades. 5.56 and 5.45mm are demonstrably superior or at the very least equal to 7.62x39mm in virtually every quantifiable category.

[7998]

I get that you are of the light and fast mindset. I think your choices have made that clear. I like fast hole punchers too. I understand and subscribe to the fragmentation damage of the 5.56 round in the right conditions. I have seen it with my own eyes with the right loads.

But if you look at all the recent offerings from serious people trying to increase the terminal effectiveness of people wielding AR type rifles, every "solution" has not been another 5mm round. They are all .30 cal again.

6.8 SPC
6.5 Grendel
.300 Black Out
etc etc etc

What do all of these rounds have in common? They are VERY similar to the 7.62x39mm in bullet weight and velocity. Many have specific advantages, or considerations factored in (Such as case length, diameter to fit in an AR magazine etc) But if you take all of these rounds and plot them out / weight and velocity. And plunk 7.62x39mm in the middle of that chart. You're going to find a discussion ending amount of similarities.

I'm not saying that 7.62x39mm is superior to 5.56 or even 5.45. But saying 5.56 is clearly superior to 7.62x39 is equally impossible to do if you are looking at ALL of the information.

Plain ol' 7.62x39mm FMJ - without witch craft bullets, or modern metallurgy has killed more people on earth than any other bullet/weapon in existence. Including nuclear weapons, missiles, tanks, and bombs.

Things that "don't work" don't hold such records. Just saying.

Both calibers are a compromise from 7.62x51mm. One leaning towards higher mass at the expense of speed, the other towards higher speed at the expense of mass. Good bullets exist for both calibers. Both cost a good deal more than the average going rate of the caliber. Both have subtle advantages over the other. Pick according to what you value more.

Beat me to it

6.8 SPC 115 gr 2,575 ft/s 1,694 ft·lbft
6.5 Grendel 123 gr 2,650 ft/s 1,917 ft·lbft
.300 Black Out 125 gr 2,215 ft/s 1,360 ft·lbf
7.62x39 123 gr (2,400 ft/s) 1,529 ft·lt

Besides weren't some our troops having trouble penetrating heavy clothing in Afghanistan?
I agree with the above about both being a compromise of .308

http://en.wikipedia.org/wiki/Hydrostatic_shock

[ungawa]

Beat me to it

6.8 SPC 115 gr 2,575 ft/s 1,694 ft·lbft
6.5 Grendel 123 gr 2,650 ft/s 1,917 ft·lbft
.300 Black Out 125 gr 2,215 ft/s 1,360 ft·lbf
7.62x39 123 gr (2,400 ft/s) 1,529 ft·lt

Which one of those four is not normally superior to 5.56?

The thread title compares a 65 year old chambering with a 55 year old chambering.