without seeing a picture of your bat, I found a 300 KSB Jumbo Softball Bat, in a search that had a department store center brand, used for mail order companies and large chain stores such as Kmart. These type of bats do not have trademarks & logos used to date Hillerich & Bradsby Co., Louisville Slugger baseball bats with conventional center brands.
The bat is most likely from the 1980's and after. -Steven KeyMan
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