| 1 | L-UR-K-S | XCR-L Upper Receiver Keymod Standard | Out of Produuction | |
| 1 | L-UR-K-N | XCR-L Upper Receiver Keymod Mini | Out of Production | |
| 1 | L-UR-K-C | XCR-L Upper Receiver Keymod Micro | Out of Production | |
| 1 | L-UR-K-P | XCR-L Upper Receiver Keymod Competition | Out of Production | |
| 2 | L-UR-M-S | XCR-L Upper Receiver M-LOK Standard | Out of Production | |
| 2 | L-UR-M-N | XCR-L Upper Receiver M-LOK Mini | Out of Production | |
| 2 | L-UR-M-C | XCR-L Upper Receiver M-LOK Micro | $550 | |
| 2 | L-UR-M-P | XCR-L Upper Receiver M-LOK Competition | $650 | |
| 2 | L-UR-M-D | XCR-L Upper Receiver M-LOK Mid | $650 | |
| 3 | L-UR-4-S | XCR-L Upper Receiver 4 Rail Standard | Out of Production | |
| 3 | L-UR-4-N | XCR-L Upper Receiver 4 Rail Mini | Out of Production | |
| 3 | L-UR-4-C | XCR-L Upper Receiver 4 Rail Micro | Out of Production | |
| 4 | L-UR-CS | XCR-L Charging Slide | $19.00 | |
| 5 | X-UR-CH-SP | XCR Charging Handle Spring | $2.00 | |
| 6 | X-UR-CH-KN | XCR Charging Handle Knob | $7.00 | |
| 7 | X-UR-CH-RP | XCR Charging Handle Roll Pin | $1.00 | |
| 8 | X-MP-RP-1 | XCR Charging Slide Roll Pin | $1.00 | |
| 9 | L-UR-CH-SH | XCR-L Charging Handle Shaft | $8.00 | |
| 10 | X-UR-CS-DT | XCR Charing Slide Detent | $6.00 | |
| 11 | X-MP-SP | XCR Charing Slide Spring | $2.00 | |
| 12 | X-UR-EJ-BT | XCR Ejector Bolt (2 Required) | $3.00 | |
| 13 | X-UR-EJ-LW | XCR Ejector Lock Washer (2 Required) | $1.00 | |
| 14 | L-UR-EJ | XCR-L Ejector | $13.00 | |
| 15 | X-UR-BR-HC | XCR Barrel Retention Helicoil | $4.00 | |
| 16 | X-UR-BR-BT | XCR Barrel Retention Bolt | $8.00 | |
| 17 | X-UR-BR-BT-CP | XCR Barrel Retention Bolt Cap | $4.00 | |
| 18 | X-UR-BD-HC | XCR Brass Deflector Helicoil | $3.00 | |
| 19 | X-UR-BD | XCR Brass Deflector Omni | $15.00 | |
| 20 | X-UR-BD-BT | XCR Brass Deflector Bolt | $1.00 | |
