For high magnification, the 30 mm (1.18 inch) tube will allow a little more light transmission - but the only time you'll notice a difference is in very low light. Chromatic aberration and spherical aberration are also reduced somewhat, since the intermediate images require less reduction and subsequent enlargement. For a low to moderate magnification scope, it's pretty much a non-issue.
Since you're going to scope a .44 Mag handgun, I'll assume you're considering something 4X or less (for hunting, 2X is really the practical maximum) so the tube diameter is pretty unimportant.
Since you're going to scope a .44 Mag handgun, I'll assume you're considering something 4X or less (for hunting, 2X is really the practical maximum) so the tube diameter is pretty unimportant.
