The percentage reduction of reload time when using Sleight of Hand

No.

This perk functions similar to Last Stand, but you automatically pull out a detonator instead of a gun.

According to the Call of Duty wikia:

Range proficiency is only available on submachine guns and shotguns. It increases the effectiveness of the range of a player's weapon by 25% (it increases damage drop distance by 25% for the weapon; for shotguns it also increases maximum range by 25%).

The example they give using the USAS-12 shotgun is:

USAS 12's damage begins to drop at 10.5 meters and its maximum distance is nearly 17.7 meters. With Range proficiency its damage begins to drop at 13.1 meters and the maximum distance of this shotgun is increased to 22.2 meters.