USGI 10.3" URG upper build

[Combat_Diver]

Posting this for historical use for down the road. These uppers are issued by USSOCOM to its Special Operation forces as a separate upper to the issued M4A1 with its 14.5" barrel.

parts


So today had the time

FN flattop M4 marked upper and various contracted small parts


After that was assembled then there's the Crane cut down and dimpeled Colt M4A1 barrel to 10.3"


Torque the barrel nut down and then gage headspace


Install the Coronet low profile gas block and LMT gas tube. Use Locktite to secure set screws.


Attach the Daniel Defense Mk18 RIS II rail


Install Surefire FH556RC-1/2-28 FH with shims and Rocksett. Then torque down


Install Knight 600m rear sight, Knight folding front sight, FN bolt carrier and bolt, Precision Grinding & Manufacturing charging handle.


Got a range tomorrow out in the desert so I'll take it out for a functions check and then issue out.


CD

[tostado22]

Awesome! Thank you

I'll save this info for a future build. My next project is a copy of the M4 I carried in Iraq

ETA: And the suppressor is a SF SOCOM556RC?

[Split66]

Lol I think several CQBR/mk18 clone junkies have tried bribing CD to mail home some of those 4 prong mounts . Thanks for the post your insight/pics/contributions are awesome.

[markm]

I wish DD would make more of the RIS II Mk18 FSP handguards for those of us who like the fixed FSB.

[Combat_Diver]

Awesome! Thank you

I'll save this info for a future build. My next project is a copy of the M4 I carried in Iraq

ETA: And the suppressor is a SF SOCOM556RC?

I believe that is the correct suppressor.

CD

[Combat_Diver]

Finally got to range and function tested on semi and auto, suppressed and unsuppressed, GTG.




CD

[markm]

Cool.

[arptsprt]

Yes. Cool.

Can you tell me your gas port diameter (assuming .070/.071?) and what buffer and spring combo you are running? Thanks.

[xWRANGLERx]

Is that the traditional 3 gas ring set up or do you utilize the one piece gas ring also do you have a extra power extractor spring in the bolt?

[Combat_Diver]

Gas port is .070, H2 buffer with standard carbine spring. Traditional 3 gas rings on bolt and extra power extractor spring.



CD