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I love my RB67. Best Camera I have. HP5+ and HC110 home developed.
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I'd recommend using something else than HC110. I did use it at the newspaper darkroom, and at home, for awhile way back in the late 70s and early 80's. But it is too much fussing trying to get a good dilution ratio and temperature for sharper, less grainy images. It's darn easy to mix, and can be used after mixing unlike the powder developers.
I normally used accufine if I pushed the film due to the conditions of the assignment, but usually microdol-x since it was much cheaper.
Check out what Ilford recommends for your HP5+ film. The photos you posted seem it have some more grain than I would expect from medium format negatives. It appears that contrast has been slightly exaggerated to lend more sharpness to the eye.
Did you scan from negatives, or print? If print, some of it (or much of it) could be the grade of paper and developer.