[CSB]

This is an old post, recently reactivated.

There are Firing Tables for the M-60 machine gun.
The nomenclature is "FT-7.62-A-2".
We had them 38 years ago in Korea. I guess they are still in the Army publication system.
They were thin booklets, about 8 pages, with the orange/brown cloth cover.
Inside were the elevation required to hit a target at a given range.
You will find the reference to the Firing Tables in the back of the operators manual.
(See image).
Supposedly, the tops of the gas port on the barrel were machined flat, so as to be parallel to the centerline of the bore (See picture of M-60, note arrows).
Then, by looking up the range desired in the firing table, the gunner would determine the elevation required. The necessary elevation would be dialed in the gunners quadrant (see image), the quadrant would be laid across the flats, and the gun elevated with the Traversing and Elevating mechanism on the tripod until the bubble was centered, not unlike elevation for a mortar tube.
Azimuth/deflection was a matter of compass work.

In theory, my six M-60's (I had a Recon Platoon, with six "Rat Patrol" gun jeeps, each with an M-60 with tripods) could be laid for direction in defilade, elevated, and commence fire towards a target without the gunners ever seeing their target.

We never even practiced it. Seemed like a huge waste of ammunition.