The poltical wing of the IRA…
Did I spell it right? How do you pronounce it? I’ve heard several variations. I’ve heard “Shin Fane”, “Shin Fine”, “Shane Finn”, “Shine Fin”.
These variations all came from news references, not anybody I know.
I would go with Shin (like the bone) Fane. rhymes with ‘vein’.
That’s how I heard Gerry Adams pronounce it.
Spot on. 
Sinn sounds like shin, as in the part of your leg.
Fein sounds like “feign,” as in “the kid may feign an illness to stay out of school.”
“Sinn fein,” by the way, is merely the Gaelic way of saying “We ourselves.”
Sinn Fein = ourselves alone
“Ourselves alone” is a common translation, but it’s incorrect. Sinn = we. Féin = self/selves. So astorian has it right.