Started working on Full Out Blues, that B7 chord is quite a challenge.
Same. I'm up to Muddy A Blues in BBG and still struggle a bit with the B7, mostly on chord changes, but it gets better every day. I probably spent a week of just playing the B7 until I figured it out. Continually practiced changing between the A7, E7, and B7 until it worked. Didn't even look at the lesson.
The best tip I found on this forum was, I think from Palo, is just find what works for you and go with it. For me I found that changing the angle of my first finger until it brushes the nut solved a lot of my issues.
I was beginning to wonder if my fat hands were not suitable for guitar but the slight adjustment changes the angle of my hand and gets my pinky to slide in clear of the fret wire. No instruction was found on this. I just figured it out on my own, and that's been one of the most satisfying aspect of this marvelous journey into learning guitar and eventually (hopefully) making music.
Now I'm wrestling stopping the buzz on the G7 as the stretch to the 6 string is a bit beyond my present hand strength. There's always something that will force you to dig deeper.
Stick with it...everyone says the same but its so true. One day its just going to work.