Mixing syringe assemblies and methods

A mixing syringe assembly comprising:

• a first barrel body portion defining a first constituent material section;
• a second barrel body portion defining a second constituent material section, the first barrel body portion slidably disposed within the second barrel body portion;
• a sealing device coupled to a distal end of the first barrel body portion, the sealing device selectively providing a fluid path between the first barrel body portion and the second barrel body portion, the sealing device comprising a first portion defining a fluid passageway which is selectively actuatable between a radially closed configuration and a radially open configuration and a second portion being axially translatable between an axially closed configuration and an axially open configuration;
• a plunger axially moveably within the first barrel body portion;
• and
• a lock configured to brace the plunger in a locked position.