Medical administration barrel with grooves and method of sealing same

A vacuum piston placement system comprising:

• a barrel filled with a volume of substance, the barrel having an open proximal end and at least one groove in an interior of the barrel, the at least one groove defining a length extending a distance from the open proximal end toward an opposing distal end of the barrel;
• a piston;
• a vacuum enclosure configured to receive the piston and being movable into sealed engagement with the proximal open end of the barrel;
• a vacuum source in fluid communication with the vacuum enclosure and configured to apply a vacuum to an interior of the sealed vacuum enclosure and barrel to achieve a lower pressure within the sealed vacuum enclosure and barrel than pressure external to the barrel;
• an actuator configured to advance the piston from the vacuum enclosure into the barrel along the length of the at least one groove, the at least one groove permitting fluid to bypass the piston, and the actuator being further configured to cease advancement of the piston upon reaching an initial portion of the interior wall of the barrel free of the at least one groove, thereby sealingly engaging the interior wall of the barrel and providing an air-tight seal inside a portion of the barrel between the piston and the distal end of the barrel and maintaining the vacuum between the piston and the volume of substance within the barrel;
• wherein the vacuum enclosure is further configured to disengage from the proximal open end of the barrel, thereby relieving a portion of the barrel between the piston and the proximal open end of the barrel from the vacuum and creating a pressure differential across the piston to cause the piston to slide further toward the substance in the barrel and minimize headspace between the volume of substance and the piston.