Federal premium (LC)
That is a contradiction in terms.
Federal is a private company owned by Vista Outdoors, Inc. Same company owns Alliant, CCI, RCBS, Speer and Savage, to name a couple.
LC is the U.S. Army Lake City Army Ammunition plant.
https://en.wikipedia.org/wiki/Lake_City_Army_Ammunition_Plant
They make the 7.62 NATO cartridge, with LC and the Year(yy) and Nato Cross-circle.
LC is operated on a contract basis by Alliant/ATK. It has been operated by other maker ammunition makers in the years since WWII.
Federal is owned by the same parent company, but does not own or even operate LCAAP. Federal may obtain LC brass, and load it commercially. Regular Federal brass is softer than LC, and the proportion of Zinc and copper is different. LC is made with cartridge brass. Federal is made with low brass.
https://en.wikipedia.org/wiki/Brass
To answer your question, if the brass says LC on the flat end, it is better brass than Federal head-stamped brass. You should not confuse, nor mix, the two. They are different.
No two kinds of 308/7.62 brass should be mixed while reloading because there is a lot of variation in 308/7.62 weights and capacities than, for example, 5.56/223 which has relative low variations between brands.