Yea you can, but you gotta keep in mind the length of insulin pins, they are very short. I would think you could hit the bi's , tri's, and maybe delts depending on bodyfat %
I've been doing my bi shots with 27g . I didn't know they made insulin needles where u could replace the pin. what's the deal. bi shot's hurt like hell.
the only trouble with an insulin needle is that the smaller the gauge of the needle the harder you have to push to get a fluid of a given viscosity through it ...in other words it is harder to push fina through 27 then a 25 gauge ...though 29 would be even harder