Before the 223/5,56mm cartridge

[RCS]

The 222 Remington Special was a Stoner design and tested during 1954-56, this became the Rem 223 and military 5,56mm (there is a slight difference between these two cartridges).

The 224 E2 Winchester was tested during the 1957 trials and loaded to 3300 fps.

Also shown is the British 4,85x49 mm (tracer) for comparison