As far as trajectory is concerned 30-30 leverution ammo trajectory is within a 1/2 inch of 154gr wolf with the x39 actually shooting flatter out to 200 yds 20% weaker huh.
The 7.62X39 is not as powerful as the 30-30
Taken from the book Cartridges of the world. 10 Th Edition
Page 54 for the 30-30, Page 337 for the 7.62x39
30-30 110 speer FP Velocity 2684 M.E. 1755
762X39 110 sierra HP velocity 2547 M.E. 1580
30-30 150 sierra JFP V. 2450 m.e,1995
762x39 159 sierra sp V 2072 M.E. 1430
so as you can see the 30-30 is more powerful then the 7.62x39
as for the trajectory being only with in 1/2 inch think about it this way the 30-30 uses round nose or F.P. bullets and the 7.62 uses pointed bullets
the desing of the bullets helps with bullet drop.