If you're referring to the British L7 GPMG, it fires the NATO standard 7.62x51 cartridge. As for the class of machine guns in general, it tends to be in the same vicinity - the first true General Purpose Machine Gun utilised the 7.92x57 cartridge, while the rimmed 7.62x54R is standard for Soviet/Russian client states.
They were sent with the Chinooks when the RAF bought them, and the GPMG was not compatible with the weapons mounts on the Chinooks.
About 3,000 fps
MG 34, MG 42, MG 3, M2HB .50, .303 Bren, GPMG (Gimpy)
The Type 80 was a Chinese copy of the Soviet PK machine gun, with minor differences.
No such thing. You can have small caliber but not low caliber.
the are also chambered for the 38 caliber, 9mm caliber and 22 caliber
What caliber of man are you looking for? What caliber of gun are you looking for?
.32 caliber
.45 caliber
30 caliber
A 5.56mm is the same thing as a .225 caliber. If you do the math, a 30 caliber is MUCH bigger!
Yes, you can shoot .38 caliber ammunition in a .357 caliber firearm.