1. 1 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Presented by Jeff Johnson Weapons Department Ordnance Engineering Directorate Naval Surface Warfare Center – Crane, Indiana – CQB Receiver – M4A1 Carbine with 10-Inch Upper Receiver

2. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. CQB Receiver M4A1 carbine with 10 inch barrel –Why a 10 ” barrel carbine? –What is the weapon configuration? –How was it tested? –How does it perform? –Questions?

3. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Why a 10 ” barrel carbine? Minimize length and weight of primary weapon Retain reliability and performance of standard weapon Maintain interoperability of SOPMOD equipment Maximize current logistics chain

4. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. What is the configuration? National stock system parts No changes to lower receiver Gas port expanded from 0.062 to 0.070 inches

5. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. What are the differences? Barrel shortened to 10.3 inches

6. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. What are the differences? Standard 4-coil extractor spring replaced with 5-coil COTS spring IAW Navy engineering bulletin

7. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. What are the differences? Standard flash hider replaced with M4QD flash hider for suppressor compatibility

8. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. What are the differences? Replacement gas rings

9. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How was it tested? 40,000 round test using 4 upper receivers fired 10,000 rounds each M855 ball ammunition 300 round firing cycle –2-4 round short bursts –4-6 round medium bursts –Barrel temperature kept below 1000 degrees F –Weapons cooled after each 300 round cycle Weapons cleaned/gaged every 600 rounds 10% suppressed Original gas rings replaced with COTS 1- piece rings at 5,000 rounds

10. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Parts breakage and replacement WpnPartRound count Anone - Bextractor spring6300 gas tube6400 extractor6500 Cgas tube7200 Dgas tube9100 How does it perform?

11. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform?

12. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Gas port erosion

13. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Barrel Temperature (°F) 713°F = max measured temp

14. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Headspace (inches) WpnInitial@ 10,000 rd A1.4661.468 B1.4651.466 C1.4651.466 D1.4661.468

15. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Reliability (mean rounds between stoppage) WpnRoundsStoppagesMRBS A10,24561708 B10,36529357 C10,35011941 D10,380101038 Cum.41,34056738

16. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Accuracy (5 round group extreme spread in inches at 200 yd) Wpn@ 5,000 rd@ 10,000 rd A8.216.1 B10.29.7 C4.911.3 D9.114.4

17. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Rate of Fire (rounds per minute) –unsuppressed WpnAvg – cleanAvg – dirty A762659 B707647 C723636 D757659

18. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Rate of Fire (rounds per minute) –suppressed WpnAvg – cleanAvg – dirty A1001980 B976957 C970971 D992986

19. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Velocity (feet per second) –unsuppressed –clean weapon WpnInitial@ 10,000change A26672438229 B26432516127 C27042488216 D26892557132

20. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. How does it perform? Velocity (feet per second) –unsuppressed –dirty weapon WpnInitial@ 10,000change A2637254889 B2678259583 C2654257084 D26822561121

21. DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Questions???