What scale does chuck berry use in the "johnny b. goode" solo?

and in what key? well that depends on the chord progression so if you could give that info too if you know it. thanks!

pentatonic minor in the key A. The chord progression is A D E. That's the way Chuck recorded it anyway.

I see alot of good desriptions above, but I think your giving Chuck too much credit. The trimatic scale? Floating between B flat and B flat major. Tuning down to G so its played in A but actually in G?
I'm sorry, Chuck is not that technical of a player. He played what he felt. According to a recent interveiw, at the time it was recorded, he/himself didn't know what scale he used. He only knew that it was in A.

1 : 1 scale

A little bit of everything you have got to see him play with Richards& friends & he still manages to screw his own stuff up.

The song is in the key of Bb - though most folks play it in A.

he is drifitng between Bb Blues and Bb major. With the bends and passing tones he is able to blend the sound like a good musician.

Most of it centers around the "blues box" on the 6th fret (for the key of Bb) and he uses hammer-on major thirds and major 6ths in the double stops.

tune your guitar down one whole step and play it in the key of G (in standard tuning it would be A) it uses the minor trimatic scale with emphasis on what I Call The joy note (the opposite of the blue note) which gives it that Ernest sound.
to get the right sound you would half to tune your guitar down one whole step . Most people would play the song in the key of A but its really played in G.