How about a 5.5" caduceus (Corpsman insignia) on my right forearm? Should be ok per Marine Corps regs correct?
Ok? Probably. Read the order in black and white and see for yourself.
Will it help you? No.
Will it hurt you? Honestly, in all probability, yes.
How bad? Nobody knows.
Listen closely everybody:
The senior leadership in the USMC does not like tattoos. Are you going to find that written verbatim somewhere? No. Will 80+% admit it publicly? No. But it's true.
I would consider any visible (but still legal per the MARADMIN) tattoo as a strike against you. That strike will carry from your selection board, to your promotion boards, to your command screening boards, to your confirmation hearings as a senior general someday. If there is somebody else just as qualified as you are, and there is only one spot left, you can bet dollars to donuts that they're going to pick the other guy.
Get used to it. It's not "fair", and it may be slooooooooooooooowly changing over time, but as far as any of us will live to see, it's the truth.
Visible tattoos on officers are akin to long hair (but within regs) and 2nd class PFTs.
It's an unspoken no-no. It's a very strongly generalized trend. Not an absolute NO GO. Sometimes I wish that they would just sack up and ban them if that's what they want, but they won't. That would require taking a stand and enforcing their standards. They should ban motorcycles, too while they're at it, and quit screwing around with the subtle passive aggressive meddling. Make a call and stick with it. But for God's sake, have what you ENFORCE be what you say that you're actually going to ENFORCE.
Now, by all means, commence with the " I know a guy who had an huge and visible X tattoo and got selected for Y" individual justifications.
Don't listen to me.