7.62x39 krinkov vs 5.45x39 krinkov

[Guest Commander Kim]

Which one makes a better transition from a 16" barrel?

the m92 has approx. a 10" barrel therefore, using the table I was given on another forum, it would lose ~60fps or 2.5% of its initial velocity

the aks-74u has approx. an 8.25" barrel therefore, it would lose ~210fps or 7.75% if its initial velocity

BUT I don't care about velocity because these rounds aren't exactly that dependent on it, like the 5.56 or .223

which one would do more damage on human tissue, does not lose too much accuracy at 50-100yds,doesn't lose it's lethality as much in afore mentioned range, and is more controllable in rapid fire?

[nightrunner]

Physics says the 7.62x39 would have better ballistics and terminal performance out of a SBR, yet be slightly less controllable.

[Smith]

By far the 7.62 and yes the 5.45 needs velocity just like the 5.56 it was designed to mimic. You don't really loose anything in the 7.62 in a shorter barrel. You still have the same sub 300m range and the power across all practical ranges is nearly identical. The same can not be said for the 5.45

[Guest Commander Kim]

By far the 7.62 and yes the 5.45 needs velocity just like the 5.56 it was designed to mimic. You don't really loose anything in the 7.62 in a shorter barrel. You still have the same sub 300m range and the power across all practical ranges is nearly identical. The same can not be said for the 5.45

The 5.45x39 doesn't need velocity to yall due to the air cavity in the tip.

unlike the 5.56 that needs velocity to fragment

[Dolomite_supafly]

The 5.45x39 doesn't need velocity to yall due to the air cavity in the tip.
unlike the 5.56 that needs velocity to fragment

Not quite.

The 5.45 does need velocity to perform just like the 5.56. 5.56 will yaw, just like the 5.45, providing the twist is correct and the bullet is not over stabilized.

Fragmentation is secondary to tumbling. If a bullet does not yaw or tumble is generally does not fragment, at least not FMJ. And the 5.56 will tumble and fragment providing the velocity is high enough AND the twist is slow enough. If is generally accepted that a FMJ 5.56 will fragment as long as the bullet tumbles and the velocity is sufficient. I will have to go back and look but I believe it is generally accepted that FMJ bullets need at least 2,600 fps to fragment AFTER they begin tumbling.

Under 100 yards either 5.56, 5.45 or 7.62 will be adequate performers with barrels of 10.5" or longer. Once you get below that the 7.62x39 will work better. 7.5" barrels in 5.56 or 5.45 will not fragment beyond 25 yards and if the twist is too fast they will perform like a 22 LR because they will not tumble at all.

[Guest Commander Kim]

Under 100 yards either 5.56, 5.45 or 7.62 will be adequate performers with barrels of 10.5" or longer. Once you get below that the 7.62x39 will work better. 7.5" barrels in 5.56 or 5.45 will not fragment beyond 25 yards and if the twist is too fast they will perform like a 22 LR because they will not tumble at all.

how about 5.45x39 in an 8.25" barrel with a twist rate of 1:6

and a 7.62x39 in a ~10" barrel with a twist rate of 1:9

[Cruel Hand Luke]

The 7.62 loses less velocity when shortened. The difference in velocity between my AKM and AK104, is less than 100FPS. Then stepping down to the 107UR is again less than 100 feet more. I lose more than that when I go from AK74 down to the AK74SU. All of them will still work, but their useful ranges are cut dramatically more so for the 5.45 than the 7.62x39. 

 

If you are just using it to punch paper then a 5.45 with an 8" barrel has plenty of horsepower to punch holes in paper and cardboard at 100 yards....but when the targets are people that are trying to kill you and the rounds need to reliably penetrate clothing and skin and muscle and go deep enough to hit vital organs then the 5.45 is not your best choice. In fact the 5.45 and 5.56 SBR length guns are really about 75 yard guns.  I'm not saying they don't still hurt past 75...I'm saying what they will do at 100 is NOTHING like what they do at 25. 

 

On the other hand the 7.62 really does not lose much velocity. As such it really does not perform much different at 100 out of a 16" than it does out of a 12". The 8.5" 7.62 loses a little more, but you still have a bullet likely to penetrate deep enough to hit vital organs. The 5.45 out of an 8.5" barrel may or may not......

[RockGeek]

I've fired SBRs of both calibers and while I love the 7.62x39mm round the 5.45x39 is WAY more controllable in the smaller platform. You can easily double tap it and keep on target. It's still got plenty of power for short range. I was blowing stumps apart last weekend with the 5.45... RockGeek

[Guest Commander Kim]

Ok. let me rephrase the question a bit.
I have an AKM and a milled AK74 underfolder.
My plan is to buy a kit, and build off of the rifles I already have.
If I go with the m92, it will be a stamped side folder.
If I go with the aks74u, it will be a milled underfolder.
I hope to eventually have both, but right now, I only have the funds for one.
Let's say if you had to "bug out" or do something of the wort, and you can only take one, which one would you take and why.
Thanks in advance.

[johnnychimpo]

 

Let's say if you had to "bug out" or do something of the wort, and you can only take one, which one would you take and why.

 

 

 

The M92. 7.62x39 ammo & mags will always be easier to find than the same in 5.45 and does a better job at their effective range. Big hammer vs little hammer.

Edited August 20, 2013 by johnnychimpo