You probably want to go with IMR 8133 it's very close to retumbo (it's also as hard to find as Retunbo though). 7977 burns quite a bit faster than 8133.
**** there are lots of other things you could use to do that, which are readily available.
As far as Retumbo, check that website listed previously. I still haven't been able to find out why it's not available at most of the usual places.
I'm aware, I looked at it already. However I'm wondering why it's nowhere to be found locally, or on popular websites. It seems like hogdon isnt shipping more or at least hasn't for some time.
It's been unavailable in northern Utah for at least 6 months. I've been trying alternatives (IMR8133, IMR7977, Ramshot magnum) but havent found anything that gets anywhere near the velocity of Retumbo in my 300 win mag with a 200g SMK.