My USAF GUU-5/P carbine build.

Since I ditched the 300 BLK build, I wanted a good 5.56 carbine. I love Retro KISS with slab side lower and non-forward assist uppers, but I wanted a 1/7" twist barrel so I could shoot 77 Grain MK 262 Mod1 ammo. The answer is my GUU-5/P carbine. The USAF are the ultimarte weapon recyclerss, with early 60s 601 and 602 Colt AR15 receivers still in service with various upgrades. Litterally anything is correct with USAF "Franken Guns" In 1979 to 1981, I carried a USAF GAU-05/P which was a Colt 601 or 602 lowerr and upper with an Aluminum XM177 stock and a 14.5:" 1/12 Colt carbine barrel.

My USAF GUU-5/P replicates anearly 1960s Model 602, late 1980s upgraded to GAU-5/P , later in late 1990s further upgraded to GUU-5/P is done

I forgot to wipe off the white lithium grease for the barrel nut threads, that got on the slip ring and port door pin. Some of those 30s actually go back to when i was in the 142 SPF 1979-1981. I have had the USAF survival knife since 1968. I decided to go with my Wilson Tactical Comp, instead of an A1 or A2 flash hider. It works really well, and I can use it with a Kydex paddle or hammerhead grip, and pinned stock when I want to be legal with high caps in Kalifornistan.

https://www.milsurps.com/images/impo...189f564b-1.jpg

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Parts list:
1) 601 NDS lower with modified Colt M16 LPK, except retro semi selector with dimples and Kalifornistan bullet button.
2) Aluminum second Gen. type CAR15 stock USGI M4 spring and standard buffer.
3) Gorgeous minty early Colt 604 upper
4) 16' DSA 1/7" twist chrome lined M4 Barrel with Wilson Tactical Comp (Kalifornication compliance when stock pinned and grip wrap used)
5) M16A1 BCG from AR15 Brick (though I have an original Chrome 601/602 slick-side BCG coming)
6) Flat Colt slip ring, weld spring and snap ring
7) Colt-ish 6 hole CAR-15 handguards from gunbroker
8) Colt 30 round mag blocked to 10 to keep it from being "Evil"
9) 70s vintage top sling adapter from B44T
10) Colt m16A1 pistol grip with cloisonné USAF medallion in grip (left over from a 1989 commemerative project I was making.

Very nice rig! I am acumulating parts for a "retro build". The barrels seem to be the missing link while the uppers and NDS lowers are easy enough to come by. Suppose a retro semi AR will be the last US milsurp (of sorts) rifle avaliable.

APEX has nice M16A1 uppers, and you can find them and slick side uppers (SP1 and 604 uppers) on the AR15.com Equipment Exchange and Gunbroker. Any lower will do until the supply of NDS catches up. I did a retro 603 on a Stag lower once.

The early CAR 15 stock on a Colt Sporter SP1 is nice too. There is a repro XM607 stock available now but a little different - but still nice

Just ordered an original Colt Model 601 chrome slickside bolt carrier (1962 vintage) to go with the 601 lower and 602/604 upper. I am, however, going with a modern Stag Arms chrome bolt. I would rather depend on a modern bolt than a 50+ year old one with untold round count.

---------- Post added at 10:45 PM ---------- Previous post was at 10:44 PM ----------

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Originally Posted by RCS

The early CAR 15 stock on a Colt Sporter SP1 is nice too. There is a repro XM607 stock available now but a little different - but still nice

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NICE 607 stock and 2 cell pouch with waffles!

I was fortunate to find a Slab Side years ago for 50.00 in very good condition . A guy at the show said it was an early Colt and he showed me the proof marks . I also back then bought the Carrier that went with it albeit not Chrome. It has no Forward Assist serration on it . What is the final deal on Bolt Carriers ? Do they have to be modified or not ? Can one use FA Bolt Carriers ? I see them being sold modified and not so whats the deal ?

I agree on barrels. It is difficult to find anything in 20in.
Sarco has bolt carriers on occasion... modified M16 also.
I have noted NEW bolt carriers on sale for around $125.00. Some with nitride coatings.

You do not need to modify Full Auto bolt carriers. Just don't use it with a full auto sear!!!!

Ima,
You are correct. I believe the ATF clarified that the use of FA bolt carriers is NOT a violation (obviously check local laws... as I am NOT a lawyer). Sarco simply had a deal at one time where they had FA bolt carriers... and modified FA bolt carriers... and of course "normal" AR bolt carriers.

I was very tempted to grab a few after the ATF ruling, as the price was fair. Of course as to the "round count" being potentially high, I was going to go with new bolt heads/ extractors.