Was wondering if the H/B 606 was used in Vietnam and if the only upper used on it was the slickside. I'm thinking about building a clone and just need more info.

Thanks

From what I've read, the 606 was never technically 'fielded' but was tested under combat conditions. I would guess it would have shared the same fate as the 607, which wasn't fielded, but tested by SEALs. The 606 was basically a HB 604, and IIRC, the only real difference was it may have been an open-bolt design. It was heavier than an M16, but didn't give any appreciable firepower advantage, as opposed to the belt-fed version, which basically was up against the M60, and that was a no-go since at that time Army brass was happy with the pig. The 606 was part of the CAR-15 family - here's a pic. The 606 is on right but a belt-fed version. I was thinking it was the left hand rifle, but I believe that's a standard XM16E1. The Colt LMG and M231 were both open bolt, and neither had a FA, so i believe the 606 didn't either. I am wondering if the belt-fed version of the 606 had a different nomenclature.

IIRC ( I really need a copy of TBR) the 606 was fielded with regular mags for testing and it was like 'why?' which led to the belt-fed version, again the response was 'why?' A great concept that went nowhere. PS - I'd love a belt-fed retro M16! Even a Ciener conversion. I wonder if you could make a SHRIKE retro?

Morg308,
Thanks for the info. I've seen that pic a dozen times and didn't catch that the one on the right was an HB.

I thought that a 606 build would be interesting but now I'm not so sure. Like you said all it really is is a HB 604

You should also check retroblackrifle.com for more info on the 606. I hope I didn't give you bad info.

I looked into it more, and it looks like I was confusing the CMG with the 606 - I thought it was just a variant. Seems like the 606 is just a heavy-barreled M6 with bipod, which they later made open bolt and added a belt-feed system to, making the CMG 1 and 2 which the later LMG was based on. At least, that's what I can come up with.

The 606 is not an open bolt design.

More info HERE.
If you have further questions tgus can probably answer them.

The 606 and 741 automatic rifles use the standard HBAR profile barrel.  This is what the HBAR profile barrel was originally intended for.

The .745" to .700" transition behind the flash hider is set back further than on a govt profile barrel.  This was done to accommodate the bipod journal and bipod stop on the end of the barrel.

The Colt Heavy Assault Rifle M1 is, as far as I can tell just a variant of the 606 (or the 606 itself).  The Colt Heavy Assault Rifle M2 was the belt-fed variant using the system developed by Rob Roy.  Colt's CMG-1 was at best tangentially related to the AR-15/M16 family, and the CMG-2 had even less in common.  Neither should be confused with AR-15/M16 family weapons.

Thanks to all for the info you have provided. The idea of building a 606 was kind of a "wonder if I could build this" thing.  

I have an A2 barrel that I could use since it looks the same as the 606 barrel from the FSB forward. I also have an A1 upper that I thought would work but it seems the only upper they used were "slicksides". Wonder if they ever had any A1s use A2 barrels as replacements? Oh no, not another idea for a build.

606




(tgus'..... I thimk)

Thanks for the pics.....

I am building a HB 606. I wanted a 20" retro rifle and when I bought one of bubbaguns new 1:7 HBAR A2 barrels off the EE here I figured the 606 was the way to go. Just picked up a NDS slickside upper. For now it will have to ride on an A2 lower until I can afford another lower.

The only part I am missing is the 3-prong flash hider. Anyone know where to get one?


norm

Midway or GunBroker

..or DPMS

texsquirrel and crackedcornish - thanks for the lead on the 3 prong.

norm