@ BOSS351CLEVELAND:
Absolutely NOT. There is considerable difference between the charge for a 7.62x54R and a .303. A straight-across swap from 7.62x54R TO .303 WOULD be disastrous.
OTOH, dumping a .303 charge straight into a 7.62x54R should give you a nice, accurate load which is a bit on the mild side.
PULL DOWN a few rounds of the Russki ammo and WEIGH THE CHARGES and bullets. The BULLETS you can use straight across. You know what the Charge is and you know what the performance is supposed to be, so you should be able to work out the RBR of the powder in the cartridges.
Remember, it will not be far from what we call 4895: that is your benchmark to work from. Why? Because DuPont built a string of powder mills across Russia for Glorious Comrade Stalin (Hero of the Workers, Peasants and Intelligentsia) and the powder-mills worked fine.... so the Russians just copied them when they needed more.
So you work out what the powder IS, dump it into a clearly-marked can and RE-MEASURE it when loading into your .303 brass. You will have some powder left over, so you can use it with commercial slugs. Remember, most .303s are at their best with FLAT-based slugs.
If you are REALLY looking for CHEAP and ACCURATE target loads, do try the C.E. Harris UNIVERSAL LOAD: a 180-grain CAST bullet ahead of 13 (thirteen) grains of Red Dot shotgun powder. With a 3-cent Gas Check on the slugs, you are looking at a nice, accurate 200-yard-plus load that doesn't kick and costs only $2.50 a box. If you really want to know what this Super El Cheapo load can do, ask TINMAN204 or BUFFDOG; they both get scary results from it.
COMPONENTS do interchange between .303 and 7.62x54R but you have to keep your wits about you.