The only markings I can find on the head are STANLEY, Made in U.S.A. There are no weight markings that I can see.
VINTAGE STANLEY VERY SMALL BALL PEEN HAMMER IN GOOD CONDITION U.S.A.
Stanley No 5310 1lb Ball Pein Hammer 39113 – The Vintage Tool Shop, The Vintage Tool Shop Unit 2, South Terrace. 10A Trinity Street. Dorchester DT1 1TU
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Also-could the part number be 306B?.
VTG Stanley Small 6 Or 8 oz Ball Peen Hammer No 3068 - 306B Wood Handle FREE S&H
SATA Hickory Handle 2lb Ball Peen Hammer with Forged Steel Head and Green Nonslip Contoured Handle - ST92314SC : Everything Else
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NOS VINTAGE STANLEY Professional Boiler Chipping Hammer Double Cross Peen $29.95 - PicClick
