That is the first negative test I have read of the 135 gr Speer SB (Short Barrel) rounds. When I carried a .38 snub, that was my round of choice.
I fired a GDHP 135g +P through drywall with no expansion. Just an FYI.
Everything I have read indicates that firing any JHP (with the possible exception of DPX) through drywall will pretty much always plug the cavity and result in zero expansion.