Not a 260 but I use a lot of BM2 in my 6.5TCU, no load data for it but I use 26gns with a 123gn ELD-M for 2550fps in a 24 inch barrel. Have gone as high as 27.5 for 2650fps but cases only last one firing and heavy ejector marking.
I also use BM2 in my 375WSM its a good powder for me
I would suggest starting at 37gns and going up at .5gn till you see pressure signs (ADI manual shows starting load of 37gns BM2 for 120gn projectile)
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