Aluminium 6061/6082 on profiling surface finish

I have a question regarding achievable surface finish in aluminium. I am currently running 3mm ball solid carbide endmill 2fl polished from haas shop, 0.075mm/fl, 0,075mm stepover, 15000rpm. Stock to leave from previous operation 0.25mm. I am getting quite smooth finish, but it is not, lets say bright or mirror-like. Am i missing somethin here? Part calls for R5mm internal fillets with sharp corners of R1.5mm.
Or getting smooth matte finish is to be expected? Or some kind of tool...

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