You should download mew torrent and then google "reloading torrent/" Then you can download the "reloading torrent" and it has many reloading manuals in pdf form. At least 5 or 6 of the manuals in this torrent have load data for 7.62x54R. Lyman used .311" and .312" bullets for working up their published loads and the torrent contains two editions of the Lyman manual (one old one new). Funny that the old Lyman manual from the 1960's says not to use anything but .308 bullets in a mosin, then the newer Lyman manual (from the 1990's) uses .311 and .312 bullets in their mosin that had a .313 bore...
But yeah, using data for .308 bullets is not a big deal if you are using starting loads... Having said that, I did get flat primers when I used 47 grains of Varget with a 150g .311 bullet in my 1939 .313 bore mosin, and 47 grains is the starting load for Varget in the LEE manual (same load data as the hogden website, and that was worked up using 150g .308 bullets). In the Lyman manual .312" 150g hornady bullets have a max charge of 48g Varget... Which is why I like to look at data from several different manuals before working up a load.