Kel-Tec SU16 vs M4A1

2003–present

1994–Present

Unknown

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

940 mm (foldable to 660 mm)

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

406 mm

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

2.27 kg

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

10 to 30 rounds

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

gas-operated

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

single-stage

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

Iron sights or rail

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