The information I’ve gathered from the web relating to Russian surplus ammo powders is below.
The main powder used in 7.62x54R has been produced in a standardize form since at least WWII and normally referred to as “VT”. The Bulgarians call the same stuff “SB 30” (or however you say that in , err .. Bulgarian). It is variously described as being similar to IMR 4895, H4895, and IMR 4064. People on the web say that you can get a yield of about 5.5 lbs of this powder by taking apart a case of 880 54R rounds. Obviously, when you take apart 54R ammo, you also end-up with – in the preceding example – 880 steel core, .311 diameter projectiles. I shoot these in my L-E - and I consider them to be great.
Others resize them to shoot in .308 bore guns. I personally wouldn’t jump at doing that because I suppose that the steel core isn’t compressible – and those who successfully resize these to .308 are presumably just thinning-out the very thick copper jackets. Thus, the resized projectile might, IMO, lack enough remaining extra thickness to conform to rifling.
Back when a case of 54R was easy to find and cheap obviously, getting 5.5 lbs of a powder similar to IMR 4895 and 880 reloadable .311 bullets was a pretty crazy deal. Now, at least where I live, you are a lot more likely to see a 1,100 rd case of 7.62x39 than a case of 7.62x54R. That case of X39 is going to yield 1,100 reloadable bullets and, say, 2.25 lbs of powder - and it will cost you around $550.
As for 7.62x39mm, generally a powder referred to as "WUFL" is used. The Bulgarians call the same powder “SB 43”. Now some 7.62x39mm is also being loaded with the same "SSNF" ball powder as is used in the 5.45x39mm. I suppose this X39 surplus powder might be a good choice in ammo that otherwise uses AA1680 or H335, but I have had the stuff work well in my 303 British.
I’m sure that there is someone out there just dying to flame me for even talking about “pull down” powders. To those I say, I have been using a non-spec powder as my “go-to” propellant for over a decade – because I bought a lot of it. What is this non-spec, scarry sounding powder called? SL47. Where did a get it? From a weird foreign-sounding place called “Hawkesbury”