What does a 40 br louisville bat mean when it has a 36 on the bottom?

Louisville Slugger 40BR Babe Ruth decal batThe Louisville Slugger bat you have 40B.R. would be a A Babe Ruth (B.R.) model. The designation 40 BR was a secondary line of retail store model bats but some were made with a decal on the barrel and you did not mention this, nor did you mention his name being on the barrel if you had a signature model bat.

Because you did not mention that the bat has anything on the barrel I believe you have a decal bat without the decal, which has worn away.

With a decal bat the bulk of the value will rely on the condition of the decal and the percentage that is left. A bat with 80-90 percent of the decal could sell in the $1,000. price range and upwards to the $4,000. range. Without the decal it will have a very low value. Maybe in the $50. price range. The decal is everything. The 36 on the knob indicates that the bat measures 36 inches.