Interested in some pics and would like to ask some questions if you have one you would like to show off if you have a Colt LMG.  Thanks!

You might have some luck posting this in the M16 section of the Armory.

I have a Colt LMG upper. What would you like to know?

I appreciate you stepping up.  I was just about to move the topic as suggested. I am really interested in building a clone of this if I can.  Is there any way you can post pictures of your upper?  I know there are pics available via Google image search, but not so many with the handguards off.  If you wouldn't mind, I'd love to see detailed pics of the handguards with and without heat shield removed, the heat shields themselves. The barrel contour and the bipod. I'd also love to see the pinned carry handle/forward grip attachment.  I know it's a lot to ask but hi-res detailed pics would be awesome!

Also, can you tell me definitively what the barrel thickness is?  I've heard it's .934", .875", and 1".  I'd love to know what it is from someone that actually has one!

And finally, do you fire yours form open or closed bolt? Is yours a semi or FA?  How does that hydraulic buffer work out for you?  I hear it's very smooth so I was thinking about buying a hydraulic buffer and I was wondering if I should buy a Colt old stock for LMG or a KynShot.  Which do you recommend?

Thank you for you consideration -Keith

I remember it was like a flip of a switch.  I would see these at the Gunshow for cheap and no one wanted them.  Then suddenly one day they were super expensive and rare.

Someone, maybe Blackthorn, made a cheap copy of it.

I have an old owners manual copyrighted in 1995 so I'm guessing about the time these first came out.  I can only guess people were intimidated with the weight and didn't see a benefit without being able to fire full auto.  But the times are a changing - remember, you use to be able to buy A1 uppers for $40 too.

Honestly I think it's going to be super hard if not impossible to find or make all the correct parts to clone this upper. I think you're much better off just buying the real deal. They can be had on GB.

These uppers run like a sewing machine on semi and FA in closed bolt. Just slap the upper in and go. I use a vltor A5 with mine but a rifle buffer will work just fine as well. There is no need IMHO for the hydraulic buffer unless you're going to run it in open bolt.

The open bolt parts with buffer will run you an least 2K for the parts and they are very scarce.

My advice is just buy the Colt LMG upper and run it in closed bolt on either semi or FA lower.

Another thing to note is that if you run in open bolt you loose semi function. Open bolt is safe/full only.

I appreciate your reasoning and if I was making a standard 5.56 LMG, I would probably start saving or sell a few to get the LMG.  But I have an old Armalite AR10 A2 style upper and I thought it would be interesting to make a 308 version of the LMG. I realize going in, it wont be perfect but I'd like to give it a shot.  Anyways, thanks for your input.

@1911nick

What is the diameter underneath the FSB? Does it use a standard FSB forging?

The fsb diameter is .8xx. It is kinda like the BULL varmint barrels

Thank you for the info.  That means the FSB should be .875, I believe as the industry standards are .625, .750, .875, .936... Of course, that's unless Colt didn't use a proprietary size.

Will a standard Colt FA bolt carrier work on these? A Youtube video stated they had enlarged gas tubes.

Yes.   Many of the uppers come without the BCG and people just use a standard one.

Another option is to clone the Colt 741/941.

That is rifle that uses an "HBAR" barrel, and an M60 bipod with adapter.

Keep in mind though that you will have massive POI shift with the bipod.

The rarest of all the LWS uppers is 2001 UMSC trial uppers. 100 were made for testing and Colt released 10 of the contract overruns.

Are these Colt R0750 LMG uppers considered to have any collector value at all?

Obviously it isn't something the general AR consumer market would consider buying like an SP1.

Obviously this is to be expected.  But one needs to remember this was considered a squad sized light machine gun, which of course means the purpose was to provide suppression fire. Perhaps the barrel mount bipod is part of the reason it wasn't accepted and Colt lost the contract to the FN M249.  

It's a cool novelty item for people with a M16 lower or a bump fire set up.  To me, it looks like the "A10 Warthog" of the M16 world... Not the sleekest or sexiest, but something about it screams "bada$$".