Roller and bearing delayed firearm operating systems

A firearm operating system comprising:

• a barrel extension attached to a rear of a firearm barrel;
• a bolt carrier group comprising a bolt with a rear cavity, a carrier disposed on a rear side of the bolt, a cam pin comprising a forward section, and a bolt extension at least partially attached to a rear of the bolt;
• a deployed configuration;
• and
• a retracted configuration,
• wherein:
• the forward section of the cam pin is disposed within the rear cavity of the bolt;
• and
• in the deployed configuration, the bolt is at least partially disposed within the barrel extension.

A firearm operating system comprising:

• a barrel extension attached to a rear of a firearm barrel;
• a bolt carrier group;
• at least two bearings disposed at least partially within the bolt carrier group;
• and
• at least one retaining rod that retains at least one of the at least two bearings within the bolt carrier group during rearward movement of the bolt carrier group.