What is a bat with only a 40 in the oval worth?

Answer 1

More information would be needed to help you out. The designation 40 was a secondary line of retail store model bats of the Hillerich & Bradsby co. that started production of this model around 1916. The dating of the bat is one of the most important factors on value along with condition. Hillerich & Bradsby Co. Louisville Slugger has used different oval center brands in their history. By identifying the center label, trade marks, and patens you can narrow down the year to what era the bat was made. Your bat might have also had a decal on it, and would explain why there is no markings on the barrel. Vintage decal bats have a high collectors value but, without the decal very low.