While most users will find that the Race Master holster functions perfectly without the additional muzzle support, there are some added advantages to using this extension: The muzzle support prevents the gun from being dislodged upwards, which could happen if bumped on the shooters thigh, or against a prop, during a walkthrough. If the holster was left unlocked, the gun can be dislodged. The muzzle support prevents this from happening.
With some gun types it is difficult to keep the gun from slightly rotating in the holster, when held only by the trigger guard. This is particularly noticeable with guns which have a totally round trigger guard, such as is the case with most 1911s, Paras and Revolvers. The muzzle support keeps the gun rock solid, and prevents any chance of movement at all. Especially with the extra heavy revolvers, the muzzle support helps carry the weight and secure the gun in all conditions.