There is a different looking piece of metal in the knob behind where you expect a trigger to be. It very likely protrudes further when the hammer is cocked.

I have the modern version. The trigger is a little more obvious here.

No trigger guard or safety, stiff hammer to cock, no power or accuracy (short barrel), LOUD and kicks hard for a .22 magnum. You need to be CLOSE to your target. I can't hit shit at 10', that bad. Fun though! The North American Arms engineering is really tight.