AR-15 variants Numbered Colt military models Numbered Colt military models

| Colt_model_no_ | Name_ | Stock | Fire_control | Rear_sight | Forward_assist | Case_deflector | Barrel_length | Barrel_profile | Barrel_twist | Hand_guards | Bayonet_Lug | Muzzle_device |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 639 | Colt SMG | 2nd | S-1-3 | A1 | No | Yes | 10 in. | A1 w/ integral silencer | 1:10 | Short Ribbed | No | A2 |
| 640 | XM177E2 | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5 Moderator or A1 |
| 645 | M16A1E1/M16A2 | A2 | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 645E | M16A2E1 | Flattop (w/ flip down front sight) | S-1-3 | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 646 | M16A2E3/M16A3 | A2 | S-1-F | A2 | Yes | Yes | 20 in. | A2 | 1:7 | Ribbed | Yes | A2 |
| 649 | GAU-5A/A | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5 Moderator |
| 650 | M16A1 carbine | A1 | S-1-F | A1 | Yes | No | 14.5 in. | A1 | 1:12 | Short Ribbed | Yes | A1 |