There are a lot of weapons which are standard issue. Assuming you're referring to the service rifle, it's the L85A2.
According to the Department of the Treasury, Secret Service officers do not carry knives as a standard-issue weapon. Please See Link
The M16 Assault Rifle or the M4 carbine is the typical primary weapon The M9 pistol is the standard sidearm hey dont forget about the standard issue knife
Glock 22 .40 calibre
M14 was standard issue military rifle before m16.
The standard issue RCMP gun is the Smith & Wesson 5946 9mm Double Action Only pistol.
The standard issue was the M 14 till 1965 and the M 16 was then issued .
Unlike the rest of the British military (who use the SA80) the most common assualt rifle for the SAS is the M4a1 carbine. During the 1990's they used the M16
The most powerful weapon used in the Revolutionary War was likely the British Brown Bess musket. It was a standard-issue firearm for British infantry and was known for its reliability and effectiveness in battle. Other notable weapons used during this time included cannons, rifles, and swords.
The Sig Sauer P226.
Depends on which military is using it. In the US military, the standard issue cartridge is the 5.56x45mm M855 cartridge. It is a 62 grain full metal jacket round. In NATO, the SS109 cartridge is standard, and this is also used by many non-NATO forces which maintain some degree of alignment with the West.
Some law enforcement agencies have used the .270 as a sharpshooter's weapon, but it was never military issue.
The Mark one and two Enfield Bolt Action Rifle in calibre .303 were the standard issue rifles (Australia) in World War I.