light weight AR build...


August 22, 2010, 05:14 AM
I've finally finished my last AR project, and I'm planning the next one. I've decided I want to build the lightest weight AR possible in .556, most likely in 7inch or 10.5 inch. I was thinking maybe a carbon lower and upper with an aimpoint micro for starters. Any other weight savings ideas?

I don't have any experience with the carbon uppers or lowers, can someone reccomend a good manufacturer? Would there be any problem with engraving on a carbon lower?

lightest car length quad rail? or possibly monolithic upper?




Also looking for a super light weight suppressor, just something to take the edge off, weight and length are the primary concerns.

This gun would mainly just be for fun, but might see some action around the farm or ride along in the tractor with me when mowing at night...

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August 25, 2010, 01:55 AM

August 25, 2010, 02:50 AM
DO you really use a quad rail ? if your going light I would ditch that idea first what ever happen to K.I.S.S. I think standerd forarm would work best for what you want it might not be tac-cool but it will be light I have seen carbonfiber freefloating forarm and man was that light. The bigest problem with quad rails is everybody has to have them to feel ok, but if your not hell bent on makeing your AR weigh 18lbs or more, keep it light the easy way, keep the junk off the rifle. If it's just for fun what is wrong with Iron sights ?

I shot a buddies who used a thin 11.5" barrel and added a aluminum flash hidder to bring it to 16" now that was fun and light, it had a A2 upper plain jane as it gets but it looked good and what a great shooting rifle

Carbon uppers and lowers are a little lighter but if you going to SBR it I would just use a normal aluminum receivers only because if you mess it up good luck fixing it and then your out your $200 stamp you may want to look up the weight of the aluminum receivers V.S. the carbon ones my guess it would be very small

Good luck on you next build plain it out first and have fun with it

August 25, 2010, 09:18 AM
I would ask Taliv, he has multiple lightweight rifles he uses for 3 gun. Wait for him to chime in.

Bartholomew Roberts
August 25, 2010, 09:29 AM
I think Taliv has a 4-something pound AR - which is the lightest I have ever seen. Of course it sacrifices a lot to get to that weight and based on the barrel alone, is going to be fairly expensive to build; but it is a neat concept rifle.

Al Thompson
August 25, 2010, 10:25 AM
I've handled Tiger McKee's "Katana" and it goes about 5.5 lbs. Thing feels like a feather and works very well.

August 25, 2010, 10:31 AM
This one is 4 pounds without the sight.
The OD on the barrel is .375" Chambered in 17 Mach 4.

August 25, 2010, 12:48 PM
I often wondered about this. Possibly a Cav-arms (no longer made?) or Plum crazy lower with a Del-ton lightweight or Bushmaster Carbon upper? I sometimes look for lightweight uppers used to get me started . . .

August 25, 2010, 01:11 PM
Think you can still find Cav Arms around and for pretty reasonable prices. I was able to handle one and it's indeed light, but also very well-made. I think a Cav-Arms lower with some of the CF pieces and a thin barrel might get you what you want.

August 25, 2010, 03:00 PM
I was looking at a Cav Arms lower yesterday for under $90. I almost grabbed one. I don't remember the site, but a guy on ARF was talking about his lightweight build and mentioned where he got it.

August 25, 2010, 09:00 PM
Cav Arms lower and a Superlight barrel would be your two biggest weight savers. I've done that.

August 26, 2010, 01:44 AM
I don't remember the site The price is $99.30 including shipping to your FFL. I'm seriously contemplating one for my next AR...a lightweight KISS rifle. I think I will be using a Del-ton Midlength w/ a lightweight barrel and stick with iron sights.

August 26, 2010, 04:07 PM
I used a stripped Bushmaster Carbon-15 Upper, a Bushmaster superlightweight 16" barrel, and a Cav Arms Lower to make this gun 5 lb. 1 oz. (without magazine). It runs great and handles and balances beautifully.

If I was not broke, I would buy another Cav Arms lower while they can still be found.

August 26, 2010, 05:19 PM
Bad pic, but here's mine.

August 28, 2010, 02:18 AM
Thanks everyone... i'll have to see if i can get a cav arms lower...

anyone know the lightest free floated rail? I'm going for super light but I still want a vfg at the least so i would want rails on it...

September 29, 2010, 01:15 PM
anyone know the lightest free floated rail? I'm going for super light but I still want a vfg at the least so i would want rails on it...

You can have rails without free-floating (like the Magpul MOE shown above).

September 29, 2010, 01:46 PM
17" carbon fiber barrel, titanium comp, carbon fiber upper/lower receivers, aluminum bolt carrier, JP trigger, clark custom carbon fiber float tube that i cut down
got around 1500 rnds on it but i only shoot it in matches and 1 day at a carbine class. i have the adjustable gas block tuned where it doesn't hold the bolt open on last round, but i've never had a stoppage in a match/class

Sorry I didn't see this thread the first time around...

my advice for light weight is:
i consider EVERY SINGLE PART on the gun above to be specialty match type parts not appropriate for use in a daily shooter or self defense gun. it's sort of like a high maintenance race car where the parts wear out quickly. expect to replace them before they fail.

if you want to go with the carbon upper/lower receiver from bushamster, get them as STRIPPED upper/lower. They will be mostly compatible with stuff you want. DO NOT buy the complete carbon15 as it is junk and you can't replace a lot of the parts.

The upper receiver did wear out where teh charging handle latches (it doesn't latch anymore). bushmaster of course offered to replace it for free, but i'm too lazy to repaint it so i just retired the gun. i wanted something different anyway.

the CF barrel is cool. however DO NOT BUY ANYTHING FROM Advanced Barrel Systems. Their customer service is horrible. They don't answer the phone. They don't return messages. And they took my money and are almost 2 years late delivering my 3rd order. As far as I'm concerned, Mike Degeneress has stolen my money.

I saved a lot of weight with the JP low mass aluminum bolt carrier. (definitely a wear part).

The handguard is from clark custom that i cut down. very light. I think the full length one is like 6 oz. And it uses an aluminum barrel nut.

Generally speaking, you wouldn't want to do mag dumps with this gun.

I never really liked the stock on this gun, but I wanted the weight ot balance it out nicely, which I think it does. If you went with a shorter barrel (17" above plus 3" titanium brake, clocked a couple degrees left since i'm left-handed) you could use a lighter stock like a magpul CTR.

Let us know what you come up with... I love seeing lightweight carbines.

I also ran an aimpoint micro T1 with larue mount. it's 3.6oz iirc

September 29, 2010, 04:44 PM
Wow! So what's the total weight on that thing?

September 29, 2010, 06:17 PM
What draw backs come alone with the cav arms lower?

September 29, 2010, 08:09 PM
I ended up buying the Cav Arms lower. Once I scape up enough $$$ I will add a BCM lightweight mid-length upper to it.

September 29, 2010, 08:14 PM
Cav arms lower.
BCM 14" middy with DD Lite 10" quad rail and perm A2X flash hider.
Magpul XTM rail covers

That's plenty light.

September 30, 2010, 09:36 AM
Anyone know the difference in weight between a Cav Arms lower and a Plum Crazy lower?

September 30, 2010, 09:51 AM
RockyMtnTactical, very nice rifle! Thats going to be my next build.

September 30, 2010, 08:34 PM
Anyone know the difference in weight between a Cav Arms lower and a Plum Crazy lower?

I cannot quantify it but the Cav Arms will be lighter as it does not require a buffer tube/plate/nut.

September 30, 2010, 09:59 PM This should take the cake without gettin' too custom.

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