M4A1 vs SIG SG 552 Commando

1994–Present

1998–present

~10,000,000+ units (including all variants and licensed production)

Unknown

838 mm (33.0 in) stock extended, 756 mm (29.8 in) stock collapsed

730 mm (stock extended)

368 mm (14.5 in) standard; 406 mm (16 in) for the M4A1 SOPMOD variant

226 mm

3.07 kg (6.8 lb) empty, 3.74 kg (8.2 lb) with full 30‑round magazine

3.10 kg

30 rounds standard STANAG, 20‑round low‑profile, 40‑round drum, 60‑round Beta‑C‑Mag available

30 rounds

Short‑stroke gas piston (M4A1 variant) with rotating bolt; original M4 uses direct‑impingement

Gas-operated, rotating bolt

Two‑stage military trigger, full‑auto only selector on M4A1; semi‑auto on standard M4

Selective fire

Standard: A2 front post and rear flip‑up aperture; optional: MIL‑STD-1913 Picatinny rail for aftermarket optics, tritium night sights, or holographic sights

Diopter rear, post front