View Full Version : Opinions on ballistics

05-30-06, 08:09 AM
I would just like some opinions on ballistics.
I have read a few posts and chatted with a few people about the 5.56x45 round, and I have noticed a trend. It seems like most people prefer the 7.62x39 round as opposed to the 5.56x45.
This really does not make sense to me, as the smaller 5.56x45 round would seem to be superior.
Could someone tell me why the 7.62x39 is favored, or is it simply the unrealiability of the Colt M16 that has given the 5.56x45 a bad reputation.


05-30-06, 12:08 PM
Stopping power. Marines have noted that sometimes in order to drop an individual it would require more than one shot. While one round from an AK will generally do the job. The M-16 if properly maintained is a very accurate and very reliable weapon , but again it just lacks the nuts thats all.

05-30-06, 09:10 PM
In the Marines I shot many rounds through the M-16A2, only had one malfunction, I believe due to a weak extractor spring. I have an AR-15 that has never had a malfunction. Saying it is unreliable is not true. The first M-16s in Vietnam did have problems, but those issues have been resolved.

As for the rounds, I personally prefer 5.56 to 7.62. It is lighter, meaning you can carry more, and at times can do more damage. However, if a person is wearing body armor or even very thick clothing, the 5.56 is more prone to being stopped, meaning multiple shots on target are needed. The 7.62 round is not going to have that problem as often. Of course, the only 7.62 AR rifle I have seen was a monster, and not something I would want to carry everywhere.

06-01-06, 05:20 PM
I see the dofference in 5.56 and 7.62 best with using the M249 SAW (5.56) and the M240G (7.62). The M240 is far more superior, in every aspect. Yes, it is heavier, but if I had to choose what to use, it would be a 7.62mm.

06-05-06, 09:07 AM
Hi again,

I have been really looking into the effectivness of the M16 vs the AK-47; as there were mixed opinions.
From what I understand (based on my studies and information I gathered here) the effectivness of either weapon would depend on the engagment and/or the marksman using the weapon.

I did the math (and I must note that mathmatics is the subject I am least capable in) and found out a few things.

Targets <100m downrange sustain roughly %12 more kinetic energy transfer "knockdown" from the AK-47 "7.62x39" compaired to that of the M16 "5.56x45" in the same situation.

However, when the target is >100m downrange, the M16 begins to do exponentially increasing kinetic energy transfer "when compaired to the AK-47" as the range increases, reaching an estimated %25 more kenetic energy than that of the AK-47 at the AK-47's maximum effective range of 300m.

By 600m (the maximum effective range of the M16) the ballistics compairson estimates %150 more kenetic energy maintained by the rounds fired by the M16 as opposed to the AK-47. (Note:This is double the AK-47's maximum effective range.)

The data sources for my estimates are gathered from reliable sources, however my ability with mathmatics is not as reliable and any corrections to this data are very welcome.
This is a simple ballistics comparison, and by no means a substitute/contradiction for/of the experience and wisdom held by combat effective warriors.
The statistical data contained within is accurate to: ><=%3 (unless I made a terrible error in my math).

Thank you,

PS:Thanks to Colt Weapons Systems, and Wikipedia for the specifications and base ballistic data on the M16 and AK-47.
Special thanks to the enemy for inspiring the development of the most advanced weapons systems on earth and giving me a hobby.
Untill victory is America's....

06-05-06, 11:31 AM
Do not forget the biggest difference, the Marine behind the weapon. A platoon of Marines with 5.56s can kick the crap out of an unruly mob with 7.62s any day of the week.

06-05-06, 12:01 PM

You might find this table handy...we used the 7.62 x 51mm as that the standard NATO round as is the 5.56 x 45mm as it too is the standard NATO round.
There a difference in muzzle velocity...
7.62 x 39mm...2330 ft/sec
5.56 x 45mm...3002 ft/sec
I think the difference come from the bullet being a might bigger.
One draw back on the 5.56 x 45mm, it don't take much to knock it off it trajectory or intented path.
Having taught the M-14, I'm still in favor of any 7.62 round.
Regardless of numbers...

06-05-06, 01:42 PM
Comparing the M-16 and the AK-47 is not the same as just comparing 7.62 and 5.56. If those are the options, I will take an M-16 with no question, even if it just shooring .22 LR rounds. If you're more than 100 meters from your target, I would throw the AK at them before I would shoot it at them. I think my chances of hitting them would be much greater than with an actual shot.

06-05-06, 04:53 PM
8 Years in and shot em both. Got the toilet seat every time with the M-14 yet I qualified Expert several times with the M-16.

Now, if I had to do it over with the knowledge and experience I have with high power rifles, I would take the M-14 and drill black all day long. why the difference?? Well probably age (17 at first) and experience shooting. I hold much steadier now than I ever did as a youngster and when I am shootin for meat I only want to use ONE round cuz I may never get that second one off (Especially now huntin with Black Powder) I am also no longer nervous about pullin that trigger and havin a little "kickback" That probably explains my higher scores with the M-16.

I still prefer lighter bullets but like the heavier power so I use a .270 for my elk hunting and it does a super job. Before ya pop off about the wussy caliber remember the .270 is a necked down 30 06/300 so has plenty of powder behind that smaller projectile to make it a flat shootin son of a gun....

06-05-06, 05:49 PM
Another $.02

As has been hinted at in earlier posts, velocity is a key FACTOR. Everyone is quoting DIAMETER of the round, but are leaving out the WEIGHT of the bullet.

To FACTOR is to multiply.

Energy = mass x velocity; or bullet weight times its speed.

The key to TERMINAL BALLISTICS, is to have that energy disipated into the target. This results in the 'shock cavity' which is what can result in the 'little hole in, big hole out' syndrome.

Note however, that with the 'big hole out', the bullet had to leave the target, meaning it still contained energy. Energy that WAS NOT placed into the target.

A 72 grain spire point (5.56) travelling at 3000 fps is NO MATCH for a 167 grain (7.62) at 2300. Compound that to the fact that the increased velocity increases the PROBABILITY that the round will pass thru, and you have a self sealing wound channel, not a shock cavity.

But if you need 3 to 4 times as many rounds to do the job, it's an upside down trade.


02-05-07, 12:57 PM
Everything here is on the 7.52x39 this is AK47, SKS not the 7.62x51. Lots of diffrance. 7.62x51 is M-14 not AK47. Are you going to shoot a raghead at 1000 yards are more with a 5.56mm I don't think so. The samething go's for the 7.62x39. M-14 is 308. The most used sniper around.

02-05-07, 02:43 PM
Regarding the weight of a projectile...can anyone tell me, how many "grains" are there in an "ounce"?

02-05-07, 04:25 PM
Regarding the weight of a projectile...can anyone tell me, how many "grains" are there in an "ounce"?


02-05-07, 11:17 PM
Just to add a note, I have clearly changed my mind since this thread was made. I now own an AK-47. Of course, it is a .223/5.56 weapon, so not everything has changed.

02-06-07, 09:32 AM
I know this is a little crazy, but just for fun...can anyone out there help me compute the muzzle energy for a cannon I used to own?
Here are the figures- 3" bore (Ordnance rifle)
59,500 gr. projectile (8.5 lbs)
1 lb. black powder (cannon grade)
approx. 600 fps (chronographed on 100 yd. range)

On a 1,000 yd. range I could consistently hit a 6' target (3' bull) after 2-3 practice shots, to "get the range." Not too bad for a "front-stuffer"! Sure was a lot of fun!