View Full Version : Lightest Quality AR Configuration
Gutshot John
07-04-08, 08:54
What is the lightest way to go?
I presume it's either a Colt 6920 or Noveske N4 Light to start.
Rail/VIS would add significant weight I imagine.
No need for anything other than a micro optic and a light.
Robb Jensen
07-04-08, 09:04
I presume it's either a Colt 6920 or Noveske N4 Light to start.
Rail/VIS would add significant weight I imagine.
Factory built or custom built?
With a semi custom/factory build I'd say start with a Colt 6520, replace the upper receiver with a flat top, and install a Daniel Defense Lite Rail or a VLTOR VIS carbine length rail. If you wanted it even lighter get the midlength VIS and 'shave' gas FSB into a low-pro gas block or install LaRue .625" low-pro gas block on it and pin it. Use a Magpul CTR stock. Use a LaRue BUIS. Use a Colt non-shrouded 1/2 circle carrier and instead of using a heavier buffer use a Wolff +10% buffer spring or a Tubb/ISMI extra power buffer spring. If you're making a SBR start with a Colt 6933 (thin 11.5" barrel).
Gutshot John
07-04-08, 09:13
Factory built or custom built?
With a semi custom/factory build I'd say start with a Colt 6520, replace the upper receiver with a flat top, and install a Daniel Defense Lite Rail or a VLTOR VIS carbine length rail. If you wanted it even lighter get the midlength VIS and 'shave' gas FSB into a low-pro gas block or install LaRue .625" low-pro gas block on it and pin it. Use a Magpul CTR stock. Use a LaRue BUIS. Use a Colt non-shrouded 1/2 circle carrier and instead of using a heavier buffer use a Wolff +10% buffer spring or a Tubb/ISMI extra power buffer spring. If you're making a SBR start with a Colt 6933 (thin 11.5" barrel).
I was primarily thinking factory built with minor mods (i.e. adding rail or BUIS, CTR, changing BCG/Buffer etc.). I would not feel very confident in shaving metal. Initial quality would be my primary interest over any modifications.
The only thing I'd want to mount is a micro optic and MAYBE a light.
Robb Jensen
07-04-08, 09:19
Like I said if you don't want to 'shave' the FSB, just buy a .625" LaRue gas block and pin it. It's more expensive in the long run.
FWIW the Lite Rail is lighter than a set of hanguards, bbl nut, delta ring, weld spring and handguard cap.........
Gutshot John
07-04-08, 09:29
Like I said if you don't want to 'shave' the FSB, just buy a .625" LaRue gas block and pin it. It's more expensive in the long run.
FWIW the Lite Rail is lighter than a set of hanguards, bbl nut, delta ring, weld spring and handguard cap.........
Thanks for the input.
Light rails in general are less weight? or specifically the VIS Receiver/Rail Combination is?
Currently I have a MI mid-length FF rail on my Stag and though I've not weighed it, it just seemed a lot heavier than the handguards.
Given the setup you mentioned above (with LaRue block), what is the ballpark price I'm looking at? Would I buy the 6520 as a lower? or would I have to buy the whole rifle to replace the upper?
Robb Jensen
07-04-08, 10:27
Thanks for the input.
Light rails in general are less weight? YES, they truly live up to their name or specifically the VIS Receiver/Rail Combination is? I find the VIS a few ounces heavier than a forged receiver w/Lite Rail.
Currently I have a MI mid-length FF rail on my Stag and though I've not weighed it, it just seemed a lot heavier than the handguards. MI rails are heavier and bigger. One of the things you get with higher end rails is much lighter, more compact, more rigid and held to much better dimensions/tolerances.
Given the setup you mentioned above (with LaRue block), what is the ballpark price I'm looking at? Would I buy the 6520 as a lower? or would I have to buy the whole rifle to replace the upper?
The LT202-2: LaRue Low Profile Gas Block - 0.625" is $69.00 on their website, I don't know what pinning costs probably another $25-40 which is why I would 'shave' it and refinish it myself if it were me.
Lower receiver doesn't matter unless you want a much lighter Cav Arms lower, the only downfall it is that it has a rifle length stock (read: too big for me and many). I mentioned 6520 because of the .625" lightweight barrel 16" barrel. Any 16" .625" barrel will be approximately the same weight, Bushmaster and CMMG make one too. Places like www.AR15barrels.com, www.ADCOfirearms.com and www.kurtskustomfirearms.citymax.com could reprofile a .750" standard barrel to .625" as well.
Cost? Basically it's like the old racing saying I heard growing up with my mechanic uncles who raced cars as a hobby "Speed costs money, how fast do you want to go?"
Gutshot John
07-04-08, 10:44
Cost? Basically it's like the old racing saying I heard growing up with my mechanic uncles who raced cars as a hobby "Speed costs money, how fast do you want to go?"
Sorry I should have been clear.
I was asking how much I should be prepared to spend for the configuration you laid out:
start with a Colt 6520, replace the upper receiver with a VLTOR VIS carbine length rail. LaRue .625" low-pro gas block on it and pin it.
I'm guessing about $2k not including optic.
The 6520 light barrel is chrome-lined correct?
The 6520 light barrel is chrome-lined correct?
yes it is: chrome lined 1/7
What is the lightest way to go? I presume it's either a Colt 6920 or Noveske N4 Light to start. Rail/VIS would add significant weight I imagine. No need for anything other than a micro optic and a light.
Convert a 6520 to a railed upper receiver, installing Aimpoint T1, and Surefire G2 in scout mount. Very light and handy.
A reprofiled 6721 upper would work as well, at negligibly less cost.
The 6920 or N4 upper isn't that heavy, but could also be reprofiled to shave ounces.
Gutshot John
07-04-08, 15:53
Can I assume that the 6520 is the most efficient way to procure lightweight Colt parts?
Does the 6520 lower give particular weight savings over other Colt lowers? or any other advantages?
Why change the upper receiver? Weight savings with the VIS? or is there another issue?
Robb Jensen
07-04-08, 15:58
Can I assume that the 6520 is the most efficient way to procure lightweight Colt parts?
Does the 6520 lower give particular weight savings over other Colt lowers? or any other advantages?
Why change the upper receiver? Weight savings with the VIS? or is there another issue?
The 6520 has a light profile barrel but an A2 (fixed carry handle) upper receiver.
If you want an A2 then it's for you. Lower weight is the same.
http://www.impactguns.com/store/media/colt_6520_car.jpg
Buy a Colt 6520. Buy a stripped CMT M4 (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=UR) (or A3, or whatever they want to call a flattop receiver with M4 feedramps) for $100. Move the barrel, forward assist, and dustcover assembly to the new upper. While you're installing the barrel on the new upper, install a Daniel Defense M4 7.0 rail for $265 (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=7.0R-DD). You may need a taller front sight post, you may not. It's a cheap part, not a big deal.
Now you're into the gun for about $1200 for the base gun, $100 for the CMT upper (you can recoup this cost by selling your "genuine Colt A2 upper" on TOS to some collector for twice what you pay for the CMT), and $265 for the rail. Add to this a Larue BUIS for $89 (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=BUIS) and an Aimpoint H-1 in ADM mount for $522 (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=APH1ADMICRO) and you're into the complete gun for $1700.
Another route would be to skip the rail altogether, keep swap the skinny handguards that come with the Rifle for a set of M4 handguards, still swap the upper for a CMT and install the H-1, and do a Surefire X300 (http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=X300) attached to the FSB via a Midwest Industries FSB rail for $35 (http://www.midwestindustriesinc.com/index.cfm?fuseaction=category.display&category_id=94).
Imagine this with a longer barrel and a micro.
http://i134.photobucket.com/albums/q111/rob_s/weights/DSC_2093Medium.jpg
The bottom gun in this pic is a mostly stock Colt 6520. The modifications are an A1 grip in place of the factory A2, M4 handguards in place of the factory skinny version, and a side-sling swivel at the front sight base. (the top gun is a suppressed mostly-stock 6933)
http://i134.photobucket.com/albums/q111/rob_s/gun%20stuff/IMG_0820Small.jpg
a bit late to this thread, but I'll add my $0.02... My Noveske build weighs 7lb as shown (Noveske N4 basic upper, Noveske lower, Aimpoint T1, LaRue tall mount, LaRue BUIS, CAR fiberlite stock, Vickers sling)
http://tinyurl.com/6eekyj
I just finished adding an X300 to the handguard (similar to what rob_s posted above) and it now weighs 7lb 3.9oz.
The 6520 and the 6933 have the lightest barrels. Even a reprofiled barrel will be heavier.
If you want a rail, get a URX or a DD. If you want you can get a 9.0 rail and trim the FSB, you can save an ounce that way.
Don't lighten the guts.
Use an M4 Enhanced stock for best cheek weld.
Skip the irons, or use Troy sights front and rear.
Use an upper without a forward assist. It is two ounces lighter.
Don't get the VIS, it is a lot heavier.
6lbs. 3 oz for rifle from factory
another 7 oz for an Aimpoint T-1
http://noveskerifleworks.com/imimg/r-lcb-556_1d.jpg
6lbs. 3 oz for rifle from factory another 7 oz for an Aimpoint T-1
Aimpoint T1 (w/rubber lens caps) + LaRue tall mount = 6oz :cool:
...this has me wondering, is there any utility in starting a consolidated weight thread for bits & pieces, as well as rifle configs?
Aimpoint T1 (w/rubber lens caps) + LaRue tall mount = 6oz :cool:
...this has me wondering, is there any utility in starting a consolidated weight thread for bits & pieces, as well as rifle configs?
http://i150.photobucket.com/albums/s95/MMcfpd/T-1_w_LT660.jpg
The 6520 flattop conversion makes for a nice, light carbine, but once you go swapping out receivers you're getting pretty far away from the "factory built" that the OP mentioned. You could use any of many flattop receivers, but if you want to keep it Colt you can get a stripped A3 upper from Brownells (probably cheaper than from SAW).
My lightest configuration has been a Les Baer receiver w/o forward assist (-2.7 oz.) with a CMMG 14.5" pencil barrel w/a perm'd Phantom, a Young skeletonized bolt carrier and bolt, a PRI FF tube with the rails removed (-4 oz.), no irons and the above pictured T-1. On a CavAid MKII polymer lower that weighs in at 5 lbs. 3 oz.
That combo has not been shot yet, though.
But the upper has been utterly reliable on its usual roost on a standard lower with an A2 grip and an Ace Ultra Light stock. In that configuration the scale tips at 5 lbs. 9 oz., and it's a very comfortable gun.
I'm assuming the old 4-position stocks weigh quite a bit less than the new 5 or 6-position collapsible (M4 style if you will)?
I went with a 16" lightweight mid-length in hopes of keeping it around the low 6's. The only addition will be that of an LMT Fixed BUIS (which I've heard isn't as heavy as it looks--anyone know?). With just these, a pinned Phantom 5C2, a MIAD, and a 5-position stock, should I have any problems falling around the 6.5 lb range?
There are some nice lightweight builds in this thread!
I'm assuming the old 4-position stocks weigh quite a bit less than the new 5 or 6-position collapsible (M4 style if you will)?
The BCM M4 buttstock body I pulled off weighed 6.8oz; the CAR fiberlite buttstock body shown above weighs 4.6oz.
And MMcfpd is right, it's 6.1oz, not 6oz as I stated (went and reweighed mine).
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