Ballistics - between the .308 Winchester (7.62x51mm
NATO) and the .30-06 Springfield (7.62x63 mm). 

New Production Ammo -

Reloading Dies can be found at  Midway USA.

Reloading components uses .308 bullets.

Brass - Very difficult to find.

If you use .284 Win to make 7.5 MAS it will require that the case head be reduced .020" and the primer pocket be recut. It can be done.

If 6.6x55 Swede is used, simply pass the brass thru a full length 7.5x54 MAS die, check length, chamfer and load. It can be done easily.

30-06 brass works well too. There'll be a slight bulge in front of the case head after first firing, and some fairly serious case length reduction will be needed, but with a power case trimmer or a mini tubing cutter it's no biggie. I like using U.S. GI brass because I have about 150 pounds of it left from a garbage can full I was given in the 60's.
 

Powder - IMR 4064 and H4895