700X is a faster powder more like Bullseye than Unique .
When Bullseye and Unique disappeared in 2012 I used 700X and Accurate #5 as replacements .
700X will stand in nicely for Bullseye and you can use it in places you would normally use Bullseye .
Accurate #5 seemed in 38 Special , 38 special +P and 357 Magnum loads to be a little slower than Unique ... I might be wrong but that's how it seemed . Not a bad stand in and I'm still playing with Acc #5 . Unique came back so I hoarded up on it .
Bottom line is you have to use what powder you can get . Good thing is data is available for just about every powder and there is a lot of overlapping in powder usages .
If you ever see Red Dot ...buy it ... that's another very versatile powder . Search the term " The Load: or what you can do with 13 grains of Red Dot " and read that article ... in fact , print it out and keep it handy ... Great Article !
Gary