Does anyone ever actually use a tuckable that much? I've tried them and even with a small gun no matter where I place the holster on my hip or how loose I left the part of the shirt that wasn't tucked in there was a huge obvious bulge. I always thought that even to the untrained eye it would be obvious as a pounded thumb that you had something inside your belt.
Sadly, most people wouldn't notice you were carrying a gun if you strapped it to your forehead. They just aren't looking and they have their own things going on.
On the bulge with tuckable holsters, I've carried a Glock 26 and a Browning Hi-Power that way and nobody ever noticed either one, although the Glock has a very obvious bulge, especially from the front where your belt unexplicably juts out from your hip for no apparent reason. Thin slide guns with older locking lugs like the Browning 1910, 1911, Hi-Power tend to conceal very well though.