Perhaps the oldest rival of the 5.56mm round is its older brother in the intermediate cartridge world, the 7.62x39mm round developed by the Soviets in the late 1940s from their earlier 7.62×41 M43 cartridge. The 7.62x39mm, despite its age, has maintained a very uniform ballistic profile. The original 8 gram (123gr) boattailed steel-cored bullet, also called “M43” like its predecessor, has become the representative load for the whole caliber, even while lead-cored flat-based incarnations like the Yugoslavian M67 ball round have proliferated.
Therefore it’s this M43 “PS” (“steel ball”) ball round that we’ll consider for our ballistic series. It is the most relevant 7.62x39mm round from a military perspective, and it’s ballistically similar to the vast majority of other loads for the caliber.
The 7.62x39mm is, thanks to its fairly heavy bullet by intermediate caliber standards, one of the heaviest rounds we’ll be taking a look at, with weights ranging from 16.3 grams (252 grains) for a steel cased cartridge to 17.2 grams (265 grains) for the brass-cased M67 Yugoslavian round.
Note: All ballistic calculations are done with JBM’s Trajectory calculator, using the ballistic coefficient appropriate to the projectile being modeled. In this case, the calculations were done assuming an AK as the parent rifle. Also, keep in mind that there is no single true velocity for a given round; velocity can vary due to a large number of factors, including ambient temperature and chamber dimensions. Instead, I try to use nominal velocity figures that are representative of the capability of the round in question.