Just wanted to know, which is round is the best out of those three, Which one would be the best on the battlefield? Rank them.
What is best?
All will kill.
Each has features that give it advantages and disadvantages.
The 5.45mm is the current standard Russian rifle and LMG round. It is flat shooting and accurate and effective on human targets.
Being a small high velocity round it can be deflected when hitting objects between the shooter and the target.
The 5.45 x 39mm came as an inferiority complex to "copy" the NATO 5.56mm which has a completley different doctrine and the Soviets did not know it.
the Soviets were experimenting with small calibre bullets before WWII.
the first assault rifle... the Federov Avtomat was a 6.5mm calibre weapon that had performance figures very similar to the 7.62 x 39mm. A 140 grain bullet moving at about 650m/s from the avtomats short barrel. Federov also developed a few rimmless cartridges before WWI in 6.5mm calibre with a 150 grain bullet moving at 850m/s it could have replaced the 7.62 x 54mm... but the Arisaka rifle had been purchased in large numbers along with its 6.5mm ammo so they went with that.
The doctrine of the 5.56mm was not to kill the enemy soldiers but favorably to wound them this would lead to the situation that enemy soldiers had to carry him or to treat his wounds in battle, binding them to the injured and keeping them away from fighting and in such manner reducing the fighting capability and destroy the enemy forces logistically.
that is a myth... the 5.56mm round was designed to fragment and dump all its energy into the target unlike the larger heavier rounds that tended to punch a small hole through and continue for hundreds of metres.
the 5.56mm was all about making automatic weapons lighter and more portable and easier to fire and allow the soldier to carry rather more ammo than with the older larger calibre rounds.
No soldier in combat will aim to wound an enemy that is shooting at him and his mates.
The Sovets did not know the doctrine behind it and were very disappointed with the innitial 5.45 x 39mm and had to find solutions, so they created the bullet with steel core, air gap at the nose and center of weight at the bottom of the projectile, through this design the bullet starts to thumble as soon as the airgap at the tip of the bullet gets squashed and enhances its lethality by yawing inside the body, the steel core assures that it has some capabilities to pierce common body armors.
Don't know where you heard that but it is not true either.
the 5.45mm round was designed from the outset to be an unstable projectile.
It was designed by a woman and she optimised the design for lethality in flesh.
The steel core is not for penetration... most Soviet military ball ammo has a mild steel core.
The design with the hollow tip shifts the centre of gravity back making it tail heavy.
the gyroscopic stabilisation from the weapons rifling keeps it point forward till impact but the rear centre of gravity makes it want to tumble.
What makes it tumble on impact is the small lead content behind the air pocket that moves forward on impact. Normally internal weight moving forward would improve stability, but because it does not move uniformly it assists in initiating the tumble. All bullets tumble, but most travel point forward for a bit before they start to tumble. the lead component in the 5.45mm means it tends to tumble on impact.
results were excellent from the start.
In comparison the 5.56mm like other bullets will travel point forward for 10cm or so through flesh before it starts to tumble. When it reaches 90 degrees the bending forces will split a 5.56mm round if it is travelling fast enough... ie within 120m with a 20 inch barrel (ie M16 or SA-80) but with shorter barrels the bullet doesn't travel fast enough to tumble and fragment... they still tumble but they don't fragment... by the time they fragment they often have left the target body.
Small light bullets are easily deflected including by bones.
The bullet turned out to be effecient but still lacks punching power of 7.62x39mm.
The 7.62 x 39mm is heavier, less accurate, but will penetrate more to reach a target... when it hits a target it will do less damage despite the larger entry wound.
The 9x39 is a more expensive round that is ideal for special forces or those who want to remain quiet.
With a 250 grain slug it hits hard but has less range than the above cartridges.
I don't know much about the 6.53mm, other than it was made in US, how do the 6.5x39mm compare with 7.62x39mm?
Smaller more aerodynamic projectile of similar weight retains velocity better extending effective range.
Overall the 7.62x39mm the case of this round was used several times for designing of rounds for sports shooting with good results in accuracy like 6mm PPC and 6.5mm PPC.
The civilian sporting version of the 7.62 x 39mm called the Russian .220 was used as the basis for the best 300m bench rest calibres available... ie 6mm PPC and 6.5mm PPC.
The 5.45 (223) is a great, very accurate round, but it is generally weak and isn't sufficient against advanced body armor. - That is the reason US forces are dropping it.
The 5.45mm has a range of armour piercing bullet options... advanced body armour will be a problem for any intermediate calibre.
Being honest, none of these rounds are very *great*...
What does great mean in a cartridge?
The 5.45mm seems to be accurate and lethal enough... the Soviets had no problem in Afghanistan with it... the afghans called it the poisoned bullet...