MP5A3 under a great coat on a felony arrest, I did use the 15 round magazine to prevent printing. Guy was supposed to be violent, had lots of guns, had stated he wouldn't be taken alive, yadda, yadda, insert line from snitch to inflame situation.
He got a really stupid expression when I produced the H&K and decided "freeze" sounded like a good idea.
In my younger days I frequently carried my 70 series Colt Gvt Mdl IWB with shorts and a T-shirt. For dress wear I carried it IWB/no holster/cross draw under a button up shirt, but you need the appropriate figure to pull that one off (hint: carved abbs ain't it). Now I'm "stuck" with the issue SIG P229 on and off duty, but I think it'll do quite nicely.
stay safe