US Troops using AK-47s

(BUFDRVR) wrote:

I think pretty much *everyone* says a 7.62 has better "knockdown" power than
5.56.

Certainly true for M14s. I'll take 180 grains at 2800 fps over 55 at 3200 any
day. (unless you want to eat the rabbit).

-- Charlie Springer

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm x
51 used in the M14.

"Regnirps" wrote in message
...
(BUFDRVR) wrote:

I think pretty much *everyone* says a 7.62 has better "knockdown" power
than
5.56.

Certainly true for M14s. I'll take 180 grains at 2800 fps over 55 at 3200
any
day. (unless you want to eat the rabbit).

-- Charlie Springer

"Bill Phillips" wrote:

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm x
51 used in the M14.

Lets rank them by momentum (in oddball units but it doesn't matter for
comparison).

..223 55gr at 3,100 fps -- 170,500
7.62x39 125gr at 2,200 fps -- 275,000 ( 1.6 times the .22)
..308 150gr at 2,800 fps -- 420,000 ( 2.46 times the .22 and 1.53 times the
Russian)

I'll take the M14 any day, but I practive with one a lot (and I picked the high
end. I have seen some NATO ball ammo at 2,300). Assuming they won't let you
have one, which of the other two do you pick?

-- Charlie Springer

If you think momentum is an effective measure of stopping power then throw
rocks; they have more of it.

Most people use energy as a first approximation, with bullet design just as
important but harder to assess.

this gives:

5.56mm x 45, 1798 J
7.62mm x 39, 1993 J
7.62mm x 51, 3276 J

Regarding personal use; I chose the 5.56mm x 45 because it is much more
controlable that the 7.62mm x 39, probably becase less momentum equals less
recoil. With an AK-47/AKM only the first round of a burst has any real
chance of a hit, the rest go over the top, the AK-74 seems to have solved
this with its 5.45mm x 39.5 round and a muzzle brake but I have not fired
one enough to have a real oppinion. Given a head or torso hit either round
will get the job done virtually every time.

"Regnirps" wrote in message
...
"Bill Phillips" wrote:

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm
x
51 used in the M14.

Lets rank them by momentum (in oddball units but it doesn't matter for
comparison).

.223 55gr at 3,100 fps -- 170,500
7.62x39 125gr at 2,200 fps -- 275,000 ( 1.6 times the .22)
.308 150gr at 2,800 fps -- 420,000 ( 2.46 times the .22 and 1.53 times
the
Russian)

I'll take the M14 any day, but I practive with one a lot (and I picked the
high
end. I have seen some NATO ball ammo at 2,300). Assuming they won't let
you
have one, which of the other two do you pick?

-- Charlie Springer

Bill Phillips
Most people use energy as a first approximation, with bullet
design just as important but harder to assess.

Bullet behaviour on impact is of decissive importance
when assessing the effectivity ("stopping power"). FMJ
7.62x39 tends to be relatively stable on impact in soft
tissue, it just turns 180 degrees to leave base first, but
does not break up nor tumble more. Thus the 7.62x39 bullet
often tends to go through the target relatively cleanly,
expending only a fraction of its energy in causing damage.

Lighter, smaller calibre, but faster, assault rifle rounds,
like 5.56x45 and 5.45x39.5, are much less stable on impact.
The higher speed and smaller diameter to lenght ratio, tends
to cause lots of tumbling in soft tissue. 5.56x45 also tends
to break up, while 5.45 with its bimetal design tends to deform.
The higher speed gives a stronger shock wave too. Thus a larger
percentage of the energy of these rounds is expanded inside the
target, causing more severe wounds at normal battlefield ranges
(at long ranges, however, the target effects are much reduced).
5.56x45 is actually _more_ effective against soft tissue at
typical ranges than slower full-sized FMJ rounds, like 7.62x51,
which tend to go through the target with much of their kinetic
energy still left. (Rifling is most relevant here too, eg 5.56
at 1:7 is more stable and less lethal on impact, than the former
standard, 1:9).

5.56 is also intrinsically better at armour penetration than
7.62x39, as the surface pressure is larger due to the smaller
calibre. Otoh, armour-piercing capability depends a lot on the
bullet design, and I dunno how the various dedicated AP bullets
compare. Full-sized rounds (7.62x51 etc) have much more kinetic
energy, and hence allow for more effective AP rounds.

5.56 and 5.45 have lower recoil than 7.62x39, allowing for
quicker/more accurate aimed rapid (semi-auto) fire and better
control of full-automatic bursts. This is a big advantage. The
recoil of 7.62x39 is however low enough for a competent user to
control an assault rifle at auto. In contrast, assault rifles with
full-sized rounds, like 7.62x51, are practically uncontrollable at
full auto. Muzzle brakes can be used to somewhat reduce the recoil,
but at a cost in the signature and/or weight and length of the
weapon.

The lethality of 7.62x39 against soft targets can be much increased
using soft point (expanding) bullets, like hunting bullets, but
these are illegal in military usage. I'd guess that a deforming
legal(?) bullet could also be developed, perhaps along the lines of
the bimetal hollow-tip FMJ 5.45x39.5. Cost would be an issue though.

7.62x39 does have an advantage over the more modern smaller
calibres though. It's less likely to be deflected by foliage,
and is also more effective when shooting through trees or berms
at a target in cover behind. I'd guess that manufacturing issues
were the historic reason why the Germans and Soviets went for 7.6*
in their AR's, rather than a faster smaller calibre round.

Full-sized rifle rounds, like 7.62x51 or 7.62x53R, typically
only have an advantage over modern assault rifle rounds at
ranges longer than normally useful for an assault rifle. The
much heavier ammunition and much larger recoil, make these
calibres badly suited for infantry assault rifles. Hence
all technically advanced armies use lighter intermediate-sized
rounds nowadays. Sniping rifles and GPMG's are another matter,
and there 7.62x51 and 7.62x53R still prevail. The particular
terrain (typical lenght of LOS) is also an issue here.

Otoh, short-barreled small-calibre carbines, like M4, have a
reduces muzzle velocity as compared to normal lenght AR's, like
the common M-16. The lower muzzle velocity of M4 impairs lethality
beyond 100m or so, which is already relevant.

Another issue is bullet drop. The faster the bullet, the less
there is bullet drop. The relatively slow 7.62x39 does particularily
badly here.the bullet drop of AKM (7.62x39) is about 70cm, which makes
adjusting the sights or aim necessary at the longer normal infantry
ranges (ie up to 300m or so). 5.56 is also superior in this respect
to the 7.62x51 at typical ranges.

Bill Phillips wrote:

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm x
51 used in the M14.

OK, I've never understood the x 39 or x 51. What do these numbers refer to?

So as not to get hit for a non-aviation post; what color is your favorite
aircraft?




BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"

In article ,
on 20 Jul 2004 02:26:43 GMT,
BUFDRVR attempted to say .....

Bill Phillips wrote:

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm x
51 used in the M14.

OK, I've never understood the x 39 or x 51. What do these numbers refer to?

Case length


So as not to get hit for a non-aviation post; what color is your favorite
aircraft?

air superiority blue


--
When dealing with propaganda terminology one sometimes always speaks in
variable absolutes. This is not to be mistaken for an unbiased slant.

From: (BUFDRVR)
Date: 7/19/2004 9:26 PM Central Daylight Time
Message-id:

Bill Phillips wrote:

The AK fires the 7.62mm x 39 which is much less powerful that the 7.62mm x
51 used in the M14.

OK, I've never understood the x 39 or x 51. What do these numbers refer to?

So as not to get hit for a non-aviation post; what color is your favorite
aircraft?




BUFDRVR


The X number refers to case length. There are several 7.62 diameter rounds out
there varying length. 30 carbine = 7.62 X 33, 30-06 = 7.62 X 63. The Russian
equivilent to the 30-06 X 54R.

Since neither the carbine or 30-06 are in common military use you won't find
many people using the metric form.

Trivia: the 06 in 30-06 refers to the year it was accepted by the U.S. Army,
1906. It replaced the 30-03 for the 1903 Springfield rifle. The round had poor
ballistics and the rifle chambered for it used poor metalurgy and was unsafe to
shoot.

Dan, U.S. Air Force, retired

The X number refers to case length. There are several 7.62 diameter rounds
out
there varying length. 30 carbine = 7.62 X 33, 30-06 = 7.62 X 63. The Russian
equivilent to the 30-06 X 54R

Thanks to all for the answer. I'm assuming the larger x number, the longer the
case and the longer the case the greater the load of powder?


BUFDRVR

"Stay on the bomb run boys, I'm gonna get those bomb doors open if it harelips
everyone on Bear Creek"

From: (BUFDRVR)
Date: 7/20/2004 7:01 PM Central Daylight Time
Message-id:

The X number refers to case length. There are several 7.62 diameter rounds
out
there varying length. 30 carbine = 7.62 X 33, 30-06 = 7.62 X 63. The
Russian
equivilent to the 30-06 X 54R

Thanks to all for the answer. I'm assuming the larger x number, the longer
the
case and the longer the case the greater the load of powder?


BUFDRVR


Generally, just keep in mind the evolution of propellents so modern cartridges
can accomplish higher pressures in shorter cases. Competition shooters are
doing amazing things with ammunition now.

Dan, U. S. Air Force, retired