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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 630 | GAU-5A/A | 2nd Generation | S-1-F | A1 | No | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5 Moderator |
| 633 | Colt SMG | 2nd Generation | S-1-F | A1 | No | Yes | 7 in. | A1 | 1:10 | Short Round | No | None |
| 634 | Colt SMG | 2nd Generation | Conflict between S-1 and S-1-F | A1 | No | Yes | 10 in. | A1 | 1:10 | Short Ribbed | No | A2 |
| 635 | Colt SMG | 2nd, 3rd, or 4th Generation | S-1-F | A1 | No | Yes | 10 in. | A1 | 1:10 | Short Ribbed | No | A2 |
| 635S | Colt SMG | 2nd Generation | S-1-F | A1 | No | Yes | 10 in. | A1 w/ integral silencer | 1:10 | Short Ribbed | No | A2 |
| 639 | XM177E2 | 2nd Generation | S-1-F | A1 | Yes | No | 11.5 in. | A1 | 1:12 | Short Ribbed | No | 4.5 Moderator or A1 |