I have a scope that has a drop-compensating reticle calibrated for 7.62x51 M80 ball ammunition.  It is mounted on a precision 5.56mm rifle, which is dumb, but it is out of necessity.  The G1 ballistic coefficient of the 75 grain ammo that I use is similar to M80 ball, as is the muzzle velocity.  Can I expect the trajectory of 5.56 ammo to closely match that of the M80 ball?

download the free version of Strelok for your phone -- punch in variable for both cartridges and compare?

Correct Answer Above

I have used Hornady's ballistic calculator to do what Hollywood_Shooter described, and the trajectories were identical.  The reason I asked is because I have recently become aware that the published values for ballistic coefficients are some sort of average value that is calculated by firing bullets over a relatively short distance (200 yards, I think), and that these coefficients change by differing amounts over the flights of the 2 different bullets.

This isn't something that I know much about.

Check out strelok for the scope library.

 They have a library of scopes in it .choose yours and see where impacts would be on the reticle chart,

I will check that out - thank you for the replies.

What is correct?  That their trajectories will be identical, but will differ from one another as their B.C.s or muzzle velocities change?