I wear an "A-Shirt" (aka old man shirt, wife beater shirt, tank top etc..) under any shirt(even T-shirts) I wear as an outer garment to keep ole slab-sides or any other pistol I carry concealed from coming in contact with my flabby middle-age bulge.
"Laws that forbid the carrying of arms ... disarm only those who are neither inclined nor determined to commit crimes. ... Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man." -- Thomas Jefferson
J MAC - I always where an undershirt to separate my body from my 1911. I could never get used to the feeling of metal against my bare skin. Plus I always figured the undershirt would act as somewhat of a 'sweat guard'.