The rifling twist rate for this cartridge is 177.8 mm (1 in 7 in), 6 grooves right hand twist, Ø lands = 5.56 millimetres (0.219 in), Ø grooves = 5.69 millimetres (0.224 in).

According to STANAG 4172 and the official NATO proofing guidelines the 556 green tip 500 NATO case can handle up to 420.0 MPa (60,916 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combination has to be proofed at 537.5 MPa (77,958 psi) to certify for service issue.

STANAG 4172 defines the Belgian ball cartridge SS109 as the NATO reference cartridge and adds a considerable number of technical requirements like a minimum pressure of 88.0 MPa (12,763 psi) at the gas port 280 millimetres (11.0 in) down the 508 millimetres (20.0 in) long standard proof barrel and primer sensitivity that are not defined by civilian C.I.P. and SAAMI ammunition rulings and recommendations