In 1923 the blocks were probably using thicker walls but….Modern hollow block? Hollow block will stop pistol fire for a while. A 357 mag will break hollow block and punch through in two rounds.
7.62 X 39 and up will destroy blocks. Haven’t tried 5.56 on it but I think fmj’s will make short work of it, steel core probably will blast right through. I would use an interior secondary barrier to stay behind and use loop holes.