Year 577 (DLXXVII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 577 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

.577 may refer to:

• .577 Nitro Express, a rimmed cartridge in the Nitro Express series of big-game hunting ammunition
• .577 Snider, a British black powder metallic cartridge
• .577 Tyrannosaur, a type of cartridge developed by A-Square in 1993 for big game hunting in Africa
• .577/450 Martini-Henry, a black powder, centerfire round used by the British and British Empire militaries

Year 577 (DLXXVII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. The denomination 577 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

.577 may refer to:

• .577 Nitro Express, a rimmed cartridge in the Nitro Express series of big-game hunting ammunition
• .577 Snider, a British black powder metallic cartridge
• .577 Tyrannosaur, a type of cartridge developed by A-Square in 1993 for big game hunting in Africa
• .577/450 Martini-Henry, a black powder, centerfire round used by the British and British Empire militaries