Lightweight build advice

[NCM]

For my next build I want to keep it light. What I don't know is if I'm reaching for the impossible. The requirements are pretty basic other than the weight. Can anyone come up with a build to meet the specs below?

Ideal Weight: 6.5 pounds loaded (incl dot optic and vfg)
Acceptable Weight: 7.5 pounds loaded (incl dot optic and vfg)

Ideal upper/rail: monolithic (VIS or similar)
Acceptable upper/rail: standard upper with a one piece FF rail

Ideal accuracy: .5 moa (with hand loads)
Acceptable accuracy: 1 moa (with hand loads)

Other parts I want to use:
FSC-556 brake/flash suppressor
KAC 600m BUIS
Standard lower and parts (no cav arms lowers)

It will really be a challenge to do the above at 6.5lb loaded.

Thanks,
-NCM

[NickDrak]

I think your weight requirements are unrealistic. The monolithic upper will add a bunch of weight right off the top. Any railed forearm will add some weight. Some more than others. I would look at the Daniel Defense Lite rails or the new Troy TRX "Extreme" rails which are both pretty light.

What about a light?

I just built up a lightweight build using a Bushmaster "Superlight" pencil barrel, a Daniel Defense 10.0 Lite rail, Aimpoint T1 Micro, Surefire X300 light, etc.... and I am still trying to shave a few ounces off of it. It is a HUGE difference from my other upper (Approx 2.25lb), and right now it stands at 8.54 loaded. Here's a pic:
http://i31.tinypic.com/r1kb9w.jpg

[NCM]

The TRX's look nice, but they still seem a few ounces heavier to comparable DD Lite rails.

My only concerns with LW or M4 barrels is POA/POI shift with suppressors mounted. I don't currently have a can, but its on the list after this build - I'd like to not have to dedicate it to only one rifle.

I'm kicking around 2 (well 4) ideas:

Using either VIS or DD Lite rails with medium/middy barrels or LW/car barrels.

On your build, The Larue FUG's I've handles felt pretty solid - are they substantially heavier than something like a KAC or other cheap plastic VFG?

I left the light off to make it easier to make the 6.5lb figure.

[NickDrak]

IMO, a weapon mounted light is the only mandatory accessory for a fighting carbine, so depending on what your application is for this gun, you should keep that in-mind.

From the #'s I have seen, the new Troy TRX "Extreme" rails are slighly lighter than the DD Lite rails. Rob's chart shows that the 11" Troy TRX "Extreme" weighs the same as a DD 10.0 Lite rail.

I am waiting on one of the new KAC handstops which should kill 2 birds w/ 1 stone for me.... The VFG duties, and my front sling attachment point duties. I love the LaRue FUG and believe it is the ultimate VFG on the market, but in the interest of saving an additional few ounces, I am going to move it from my lightweight build to my other general purpose carbine.

The barrel is arguably the best place to save weight, so I like the Colt or Bushmaster "pencil" profile barrels for these lightweight builds.

Overall I am extremely pleased with my new lightweight carbine build. Having a fully accessorized & loaded, 8.50lb carbine is very sweet.

[NCM]

IMO, a weapon mounted light is the only mandatory accessory for a fighting carbine, so depending on what your application is for this gun, you should keep that in-mind.

From the #'s I have seen, the new Troy TRX "Extreme" rails are slighly lighter than the DD Lite rails. Rob's chart shows that the 11" Troy TRX "Extreme" weighs the same as a DD 10.0 Lite rail.

I am waiting on one of the new KAC handstops which should kill 2 birds w/ 1 stone for me.... The VFG duties, and my front sling attachment point duties. I love the LaRue FUG and believe it is the ultimate VFG on the market, but in the interest of saving an additional few ounces, I am going to move it from my lightweight build to my other general purpose carbine.

The barrel is arguably the best place to save weight, so I like the Colt or Bushmaster "pencil" profile barrels for these lightweight builds.

Overall I am extremely pleased with my new lightweight carbine build. Having a fully accessorized & loaded, 8.50lb carbine is very sweet.

I found numbers for both on PKfirearms online store. They list:

TRX 9" = "Weighs 13.0 ounces with barrel nut, rails, and rail mounting hardware."

TRX 13" = "Weighs 15 oz with included barrel nut and optional rails"

DD Lite 9" = "Weighs an astonishing 11 ozs (including the bolt up plate, barrel nut, and bolt up screws)"

DD Lite 12" = "Weighs only 14 ounces"

I wonder if PK weighed them all or are using manufacturing numbers. Companies to like to play with numbers for advertising purposes. PK includes the optional 3,6,9 rails and screws as well - it probably would beat the DD without them, but then you don't have those mount points.

Those are the numbers I was using since they were all from the same source.

[Stickman]

The Larue FUG's I've handles felt pretty solid - are they substantially heavier than something like a KAC or other cheap plastic VFG?



If you are truly looking to go as light as possible, you are not going to use anything heavier than absolutely necessary. That means no QD VFG when you can do without, or if you feel you can't live without a VFG, you are going to end up with a cut down KAC or TD.

For rails, there is no lighter rail that I'm aware of than the DD M4 series. By removing the steel barrel nut, and replacing it with the aluminum DD nut, you are getting a rail that is lighter than the parts it replaces.

You've got to cut everything possible as a little here, and a little there add up quick.

[OfcPowder]

This looked like a great post to ask this question -

I too am looking to build a lightweight rig. I have a 14.5 colt barrel, a DD Lite FSP rail that are part of the build.

My question is, does anyone know of a good place to have the barrel lightened. It is currently the M4 profile, and I was thinking of having it taken down to a "pencil" barrel for maximum weight savings. Anyone done this? Any thoughts on it?

[NickDrak]

This looked like a great post to ask this question -

I too am looking to build a lightweight rig. I have a 14.5 colt barrel, a DD Lite FSP rail that are part of the build.

My question is, does anyone know of a good place to have the barrel lightened. It is currently the M4 profile, and I was thinking of having it taken down to a "pencil" barrel for maximum weight savings. Anyone done this? Any thoughts on it?


ADCO does good work. I believe they will charge around $130 to have the entire barrel re-profiled, or just $65 in-front of the gasblock.

[rob_s]

I'll second ADCO. While I've never had them do re-contouring they have done other work for me with a very fast turnaround and fair prices.

[CCK]

Les Baer makes an upper with out the forward assist, only the deflector. If you are so inclined that will shave some weight without going to odd ball materials.

Chris

[longrange18]

What about a KAC hand-stop instead of the VFG?

http://www.knightarmco.com/shop2/products_pictures/25460_pic.jpg

[federalist22]

Les Baer makes an upper with out the forward assist, only the deflector. If you are so inclined that will shave some weight without going to odd ball materials.

Chris

Sun Devil also makes a slick side upper receiver.

Has any checked out the "carbon-fiber" receivers like the ones Bushmaster makes? Are they worth a look? Do they stand up to use? Are they really that much lighter weight? Are they a gimmick?

[Keebsley]

What about a KAC hand-stop instead of the VFG?

http://www.knightarmco.com/shop2/products_pictures/25460_pic.jpg

I think it was either on M4C or LF, but RetreatHell replaced his Larue FUG with a KAC handstop because I believe the difference in weight was at least a good 3 to 4 ounces in weight savings.

So definitely a valid way to shave a good couple of ounces of your build.

[alt154shiver]

Has any checked out the "carbon-fiber" receivers like the ones Bushmaster makes? Are they worth a look? Do they stand up to use? Are they really that much lighter weight? Are they a gimmick?

I too would like to hear about these. I'll be putting together a shopping list for an ultra-light build while I'm deployed.

[Keebsley]

Sun Devil also makes a slick side upper receiver.

Has any checked out the "carbon-fiber" receivers like the ones Bushmaster makes? Are they worth a look? Do they stand up to use? Are they really that much lighter weight? Are they a gimmick?

I've had a Bushmaster carbon and I wasn't very fond of it. Traded it in for a standard receiver. You can probably do some research and notice that a good number of people don't suggest it. I guess if it was just for plinking every other month or so and not a hard use AR, then go for it but don't expect it to last as long as something like a forged receiver.

[Quentin]

A buddy has a Carbon-15 and my first impression was negative. But we've taken it out many times in the last year and now I love it. Very light and manuverable. And always works. Also it takes standard AR components including the fcg.

I would be concerned how durable the composite material is. Hopefully nothing like all the pictures of broken Vulcan lowers!

[rebelEMPIRE]

Working with carbon composites, I can definitely attest to its strength and weaknesses. The carbon receivers on the market today are not engineered to the best designs, I don't think.

Let's keep in mind that carbon fiber composites, if done properly, is stronger than steel and lighter than aluminum. Race cars' carbon fiber hoods can support two full grown men standing on top of them without flexing. Formula 1 cars' brake rotors are carbon. Aircraft brake rotors are carbon. It's quite evident that those are extremely high heat and stress areas.

Although composite materials do not corrode, carbon fiber can and will weaken to ultraviolet exposure; an anti-UV coating is necessary to preserve integrity.

It's only a matter of time before a quality composite receiver is designed. I would definitely jump on the bandwagon for one. But until then, aluminum does the job just fine.

-rebelEMPIRE

[NickDrak]

If you are looking to slap together a carbine that is sooper light only for the sake of being light, then maybe the Carbon-15 woulf fill your needs.

If you are looking for a lightweight carbine that actually runs reliably, then forget the Carbon-15's and the Vulcan's and stick with MilSpec upper & lower receivers.