Driving band configuration doesn't match any of the Lyman/Ideal designs. Here's a complete compendium of their past and present bullet designs: http://three-peaks.net/Lyman_and_Ideal_Bullet_Molds.pdf

If I had to guess, I would nominate the RCBS 115 grain gas check design that someone milled the top of the mold blocks off of to create a flat based bullet. https://www.rcbs.com/bullet-casting/moulds/bullet-mould-.30-115-sp-535/16-82009.html (Note the illustration in this link shows a shorter nose than other illustrations of this bullet do.)

Last edited by gnoahhh; 12/07/22.
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