*** LAST UPDATE 4/14/2024 ***
This is intended to help people who want to build lightweight rifles and/or want to lighten up an existing rifle. This is not necessarily intended to be a comprehensive list, as it only includes parts that are lightweight or nearly so.

RAW DATA SPREADSHEET HERE, v1.03

An updated Parts Database made by another user is here:  
Check this Google Doc
It may be more complete / more updated.

My recommended cheap / light build if you only want to get under 5 lbs for ~ $1k.


For a little more money (about $150 more) you can save a few more ounces


Key:
U = User Data
M = Manufacturer
C = Calculated

Weights listed are in ounces.

Parts in purple are amongst the lightest options


****Upper Parts****
Muzzle Devices
A2 Flash Hider       2.15 U
A2 Extended
Mag Tactical             1.90 M
BE Meyers               2.50 M
AAC Brakeout 51t   4.20 M
AAC Blackout 51t   4.30 M
VDI Manimal            1.48 M
Rainier Mini-Comp    1.44 U
ALG Single Chamber Brake 2.01 U
V7 Titanium   1.35 M
V7 Ti V-grooved  1.25 M
Venom Defense hybrid steel muzzle brake 1.48 U

Charging Handles
PSA Milspec  1.13 U
Breek Arms Warhammer 1.0 U
Spikes Milspec 1.07 U
Rainier Raptor 1.42 U
BCM Gunfighter Med   1.24 U
BCM Gunfighter Small
V7 Ultra-light charging handle  1.04 M

Bolt Carrier Groups
LMT Semi-Auto 11.14 U
Umbrella Corp Full-Auto 11.46 U
RRA Semi-Auto 11.26 U
Spikes NIB FA 11.8 U
Colt F/A BCG 11.56 U
BCM F/A BCG 11.64 U
PSA F/A BCG 11.50 U
Red X Arms Ti 7.81 M
JP LMOS Bolt Carrier 6.25 M
JP Bolt Carrier (full mass) 8.5 M
Young Man. SLC carrier   7.1 U
FN Bolt Only 1.5 U
Smith Aluminum carrier w/ key 3.7 U
PM&T Ti carrier w/ key 5.1 U
V7 Systems Ti Carrier  5.7 M
V7 Systems Ti BCG  7.9 M
DSA Low-Mass Steel BCG 9.1 M
DSA Aluminum BCG 5.2 M
OdinWorks Low Mass BCG (steel) 9.0 MU
WDR Titanium BCG  7.8 M
FosTecH LOW MASS BCG (Nickel Boron) 8.5 M

Gas Blocks
Aero precision 0.625 adjustable
BCM 0.75"  1.30 U
BCM 0.625" 1.928 U
Daniel Def LPGB 0.750        1.28 M
Daniel Def LPGB 0.625        1.92 M
V7 Systems Ti LPGB 0.750  0.74 M
V7 Systems Ti LPGB 0.625  0.71 M
2A Armament Ti 0.750   0.70 M
VLTOR 0.625" (set screw)  1.4 M
Parallax Tactical LPGB          1.47 U
SA 0.75" adjustable 1.8 U
Samson MFG lite 0.625"  0.6 U
YHM LP w/ set screws 1.43 U

Gas Tubes
Del-ton Carbine 0.63 U
Carbine Length  0.7 C
BCM Midlength 0.757 U
V7 Midlength 0.94 U
Mid Length  0.8 U
Rifle Length 0.9 U

Dust Covers
Dust Cover Assembly  0.75 U
Dust Cover Ass., V7   0.37 M
Mako Poly Dust Cover: 0.2 (discontinued?)
UBCM Dust Cover 0.506 U
BCM Dust Cover Pin 0.211 U
BCM Dust Cover Spring 0.021 U
Strike Industries Ultimate Polymer  0.3 M
Strike Industries Ultimate overmolded Polymer 0.5 M
Strike Industries Polyflex  0.3 M
Magpul Polymer   ?

Forward Assists
BCM Forward Assist 0.712 U
BCM FA Spring 0.058 U
WOA Forward Assist Assy  0.74 U
Northtech Ti Forward Assist 0.501 U
Northtech Ti FA Spring 0.050 U
Schuster Mfg FA plug  0.10 U

Upper Receivers
2A Armament Balios Lite stripped, no FA  5.8 M
Aero Precision Forged Stripped 7.16 U
Aero Precision Forged Stripped; no FA   6.4 U
Fostec FLITE Elite Stripped 5.92 M
Kaiser X-7 Poly Upper: 5.5 M
Mega Arms forged stripped 6.9 M
Mega Arms Billet Upper, 9.4 M
Rainier Forged, Complete  8.6 M
Rainier Arms Forged Stripped 7.08 U
Spikes Forged complete: 8.4 U
V7 Weapon Systems Forged Complete 7.7 M
V7 Weapon Systems Forged stripped 6.8 M
V7 Weapon Systems Enlightened 6.0 M
V7 Weapon Systems Enlightened (lithium/aluminum) 5.8 M
Forged no FA, complete  7.3 C

Do those of you using empty aluminum buffers bother putting the roll pin back in after removing the weights (e.g. 3 oz down to 1 oz)?  With no internal forces acting against the bumper, I can't see how it would ever work itself loose.  And even if it tried to, bottoming out against the back of the buffer tube should correct any such tendencies.

Eliminating the roll pin pushes it down into the 0.9 oz range.

The rest of my parts arrived today.  The MFT commercial-spec Minimalist stock is only 5.6 oz.  The packaging matches the 5.8 oz on the website, so the PWD must have old info.  Unfortunately, that was just a lateral move, as the SLR Sentry 6 (0.625) gas block and ODIN Works gas tube came in at 1.4 oz and 0.8 oz, respectively.  (My scale is limited to 0.2 oz precision, but they added up to 2.2 oz, so probably no rounding there.)  I believe they are listed at 1.2 oz and 0.7 oz.

Why not use a taccom 2 piece polymer buffer? Mine have been great for semi-auto in both 223 and 308.

Weight savings didn't seem substantial, plus being in the spot you least want/need to cut weight, so I opted for simple and inexpensive.

On a different note, parts compatibility and functionality is kicking my butt on this build...

Takes extreme effort to pull the charging handle, to the point my fingers are nearly blistered.  (I've nearly worn through two CH's in trying to smooth out the Fostech upper.)  No difference with a regular, previously used BCG and CH.  Pulling the takedown pin and pivoting the rear of the upper up slightly helps immensely.  Two different poly buffer tubes, same thing.  The Fostech upper works fine on an existing lower, so you'd think the TN Arms lower is to blame, but then the TN Arms lower works fine on an existing upper.  Damn tolerance stacking.  I've had enough problems with that TN Arms lower's specs, such as takedown and pivot pin holes being spaced wrong, and the safety takedown pin detent hole being too close to the fire control pocket for the upper receiver's lug to clear the tip of the takedown pin, that I might just start over there.

Aero Precision Ultralight scope mount had the front ring's clamp seated too high.  Reading about how easily those hinges can be busted by adding tape to protect the scope tube from marring (reduced I.D.), had me thinking that half mm or so could be bad news.  AP support said to send it in after looking at pics, but by the time I had heard back, I got it seated well enough with some persuasion to give it a go.

Leupold Mark AR Mod-1 3-9x ... the Firedot has a mind of its own.  I have an inquiry into support to figure out if something is wrong with my button.  It sticks in place every few presses and then pops (like releasing suction) after unscrewing the cap a few turns.  Sometimes it randomly turns on or off, as the battery can't decide whether it's being pressed or not.  What a strange design, pushing a spring-loaded battery against a contact to activate the circuitry, with a rubber diaphragm to provide the pressure.

Still waiting on the missing parts from the Plumcrazy LPK.  The ball got dropped there for a week; supposedly was shipped out today.

Also, I ordered the Faxon Pencil barrel from Cheaper Than Dirt!  I couldn't believe it when it showed up in an un-padded soft mailer.

The good news is, I didn't have to heavily torque the barrel nut to time the gas tube.  I was worried I would need to get a reaction rod before proceeding, but 30 ft-lbs lined it up almost spot on and it was still in a perfect spot when I bumped it up to 33 (adjusted for lever arm).  I didn't want to try putting 80-90 ft-lbs on that light upper!

Sorry but 0.20 ounce precision is just not good enough for any data base. Not for what we do here, one gram is a lot of weight to loose now.

My larger (up to 8 pounds) scale is good for 1 gram, my one ounce scale is good for 0.10 grams.

I know the limitations, that's why I specify it.  You're not the only one building lightweight guns, ya know? The stuff I'm reporting is the in-between weight items that wouldn't interest you, but cater to what the majority of people are more likely to be looking at.

@blackrice
you should probably get Fostech to swap out your upper

I ordered two from Classic Firearms and one upper was definitely distorted and very very hard to move a bcg inside

I still need to contact Classic Firearms or should I contact Fostech? I think I'll contact Fostech directly and see what they'll do for me

I remember you mentioning that.  The thing is, the upper by itself isn't a problem.  The CH and BCG move fine, albeit a little gritty with that pebbly finish, when it's off the lower in question, or on a different lower.  I haven't lubed it yet, since I don't like an oily mess when I'm still fitting parts, but that ought to make the movement smooth enough when it's on a lower without the tolerance stacking issue.

Plus, after shaving the FA and deflector, I'm probably SOL on warranty stuff.

p.s.  The build planner's final numbers are 3.86 lbs, and the actual weight is 3 lb 14 oz (rounded to the nearest 0.5 oz above 2 lbs) = 3.88 lbs -- with steel safety selector and buffer retainer until the polymer replacement parts arrive -- so I'd say the high capacity postal scale does just fine.

While I would tend to agree, if the best measurement currently available is to that degree of accuracy "it is what it is". non-super-accurate data is better than no data, especially when it's an item that isn't on the ultra ultra light range of products. There are users of the database that aren't extreme LW builders, and for that crowd, 0.20oz is probably accurate enough. For the nuts among us, sure, we want 0.00001oz accuracy and would be upset if the published data was off by 0.2, but until better #s come along, we're kinda stuck with iffy data at times. It's not like I can go to everyone's house and check their scale's calibration so on some level we are all at the mercy of others in this thing.

Aluminum BCG for sale in the EE for $100:

https://www.ar15.com/forums/equipment-exchange/Lightweight-Aluminum-BCG----100-Shipped/159-1795815/

Now, go buy a better scale bR!  

I have a great scale already!  Very accurate over the entirety of its 75 lb range.  It's just lacking precision...  FWIW, the 0.2 oz precision is close to 0.1 oz, since:  a) it'll bounce between 2.0 and 2.2 if it's closer to 2.1, and b) the tighter 5g range can confirm in-between values.

I've looked at powder and jewelry type scales numerous times, but I refuse to buy anything of the sort that's battery powered (I won't waste resources out of convenience -- I use a rake instead of a leaf blower -- and have always distrusted the accuracy of anything with a diminishing power source), which eliminates most of the inexpensive options.

https://utahgunexchange.com/ads/titanium-bullet-cam-pin-brand-new/ cam pins are back. Act fast!

I checked with Incognito Arms about the possibility of a beaver tail grip and was told they will be offering one at some point.  Of more interest to most of you, though, I was also told that pre-order on the ultralight grip will be opened up soon.

" />

SORRY, but it will never be about buying a better scale. It doesn't matter what form the scale is, mechanical or electronic. Each scale must be used within it's accuracy range. You could allow people to weigh their AR parts on a bathroom scale, that might be accurate for sole people.

But this thread is about LIGHTWEIGHT PARTS with WEIGHTS. Accuracy does matter, and the scale calibration matters. I have seen people here purchase parts because they appeared to be lighter in the database. But because of inaccurate scales and calibrations the parts were different weights that published.

I wonder how people would have felt if I had measured my 50 gram Incognito stock with a different scale and stated it weighed 2.4 ounces. Then came back that it was actually 1.79 ounces?

A scale is only as accurate as the calibration weights!  For weighing gold, usually the accuracy is insured with very expensive calibration weights.

You can buy inexpensive calibration weights that are accurate for what we do. A tenth of a gram resolution is good enough for any ultra light AR parts database.

With your 75 pound scale, what weights to you have for calibration across it's range? It might be accurate only at 50 #, and could be way off at 5#.

This place has some mechanical triple beam scales that aren't too expensive, but you still have to buy calibration weights.  https://www.oldwillknottscales.com/

Sorry for the rant, but I was a Chemistry major and my first introduction to scales was as a sophomore in high school with those beautiful scales with wood bases enclosed with glass on the 4 sides and top.

It's been checked throughout its range and is spot on with USPS/FedEx/UPS scales in the 1-16 oz range and on up to 75 lbs, and matches reported weights in the partial-ounce ranges.  I'm confident in its accuracy and repeatability.  You're obviously not, but hey, none of the stuff I'm reporting caters to you or anyone sharing your level of the sickness.

As a chemistry major, you should be more careful with your use of accuracy vs precision.

Well I called about the titanium cam pins in Utah gun exchange, the woman I spoke to said more were on the way and I would get an email when they were ready.

R2B has the 16" Faxon Pencil barrel (5.56) in the Labor Day special for $140 shipped:

https://www.righttobear.com/FAXON-FIREARMS-16-PENCIL-5-56-NATO-Mid-Length-p/15a58m16npq.htm

That's a few bucks cheaper than I found with any of the promos last month.  Probably won't last long, judging from how quickly their $144 moving special sold out.

Posting here instead of the Deals thread, because it's the top choice of many lightweight builds.

If you text the guy, he'll text you back when they are in stock and you can order asap. That's what I did. Ordered 2 just today.

What do you guys think is the lightest possible gas block available? A Ti one that is currently offered by someone or taking a lw non-adjustable one and putting a set screw in it?

Without a doubt it's going to be a non-adjustable one. The extra materials required to make it adjustable takes it out of the league of "LIGHTEST POSSIBLE GAS BLOCK AVAILABLE"

Isn't it the TI Battle Arms the lightest?

I believe this is all correct. The BAD .625 gas block is a little under half an ounce IIRC.

Wouldn't a clamp-style gas block be lighter than a set screw one, all things being equal?  The clamp block should have a bit more air space in the bottom half, but maybe it needs to add mass elsewhere to account for the flexing?

If the BAD Ti non-adjustable block came as a clamp instead of set screw, I'd of been very tempted to go that route along with an adjustable gas key.  Set screws and dimpling an already thin barrel profile just didn't appeal to me.

Not sure, but the BAD TI is shorter than most gas blocks so it makes up for the fact that there is no gap as the clamp on style have.

I didn't dimple or use the set screws with mine as I had the barrel shop pin it instead.

But... that said... I have ZERO concerns about using set screws and appropriate dimples on a the thinest of thin barrels.. the gas block seat is .625 on all .625 barrels and there are many such .625 gas seats dimpled out there with zero issue. That is not the smallest OD on a feather weight barrel by far...

Did anyone else notice that Bobro changed their low rider BUIS to a locking style instead of a detent or vice versa? Advertised weight is the same. SWFA has the ones with a lock button but the Bobro sight still looks like what I have.

https://swfa.com/bobro-buis-lowrider-sight-set.html

http://www.bobroengineering.com/view/product/49/

It doesn't look like the shortness (and minimized curve) would keep it from working as a clamp-style block.  So, what makes it lighter in the first place, could be made lighter still.

Well, I should add...I despise irreversible "damage" when there are good alternatives.  For example, I'll take the appropriate loctite over staking any day.

BAD Ti 0.625 with the forward set screw portion chopped off, and the portion of the gas block journal that isn't used turned down. Throw in a Ti set screw and you're good to go.

I'm interested in the Faxon 13" carbon fiber handguard.  Anyone using have opinions?   Sadly looks out of stock everywhere.

Check out smokes new handguards on Facebook. I think their new ones are much lighter.

I really really like the look of the new smoke composites, the old round ones not so much.

That said, it seems the V7 Hyper Lights are as light or lighter.. ??

I've built a bunch of light weight builds, reused some parts from my "Toy Light" build, and need to rebuild it with what are now lighter parts on the market. At one point I was going to do SC CF handguard, but it looks like the length I need is going to be lighter in the V7 Hyper...

Honestly, what we can use Smoke... is a Carbon Fiber blade / arm brace that goes on a milspec carbine receiver extension. There is another company making a milspec carbine carbon fiber receiver extension. Make the arm brace and now we have a CF arm brace alternative to the SBA3 for those building light weight pistols.

I'm looking at those v7 as well.

Also check out dark hour defense, they have magnesium handguards. The only only CF tubes lighter than a proper magnesium setup with an aluminum barrel nut are Clark custom and brigand arms blade/edge. I guess any bare bones tubes would be a hair lighter than magnesium but unless you're really going for the second lightest rifle in the world (we all know who has the lightest) or you just want an all polymer upper/handguard combo 1.5 oz isn't that much weight. Oh BTW I am finally getting my 2 bullet titanium cam pins today!!!

Got some new data and build info on a pistol lower I'm working on.

First up is the Fostech lower with the lightening cuts in the trigger guard, both with and without pins:

Next up is the polymer receiver extension.  Since I'm doing a pistol build I shaved off the slots for an adjustable buttstock, shaped and sanded the inner lips to make an anti rotation notch for the buffer pin, and rounded out the opening a bit to prevent the carrier from catching.  It started out at 71 grams and after hacking, sanding and reshaping the front end it is down to 60 grams:







Here it is in the Fostech lower with a smoke composites carbon-fiber endplate (old smooth style) and lightweight castle nut.

Next part of the project was a lightened pistol grip.  I took the one from the New Frontier LPK that I am using and too to it with a sanding drum, drill bit and rotary too.  What I didn't realize is that this was a pretty beefy version of a milspec grip, it's pretty thick on the inside.  It started around 84 or so grams, and half way through working on it, I weighted another one I had on hand, and they came out to the same weight somewhere in the 78 or 79 grams. oh well.

I liked what I had done for shaping so far, so I just kept on it with the boat anchor I started with and did a little swiss cheesing on the sides and back, but not enough to compromise the strength of it.   I kept the checkering because I like the extra grippiness, and sanded in some finger grooves up front.  I really like the way it looks and feels when it was all said and done. And I was able to cut it down to 64 grams. Not the lightest I know, but not a bad start for my first custom sanded grip.

Last bit on the lower project: I put in the New Frontier LPK, substituting a V-7 LW bolt catch that I had left over, threw in a Taccom buffer and flatwire spring. Eventually I want to put on a KAK blade to round it out, but for now I gotta save up for the pistol upper build.

BTW looks like Smoke Composites updated their web page with the new style hand guards including (M) weights.

http://www.smokecomposites.com/hand-guards

And you can get their long awaited carbon fiber/Ti muzzle device for the low low price of $120
But I don't see a weight listed for it yet.

Last thing that happened this weekend, Looking at my original LW build while putting together the pistol lower, found my Tegra lower receiver has a crack, time to use that lifetime warranty...sigh.

The rails seem heavier than the v7 Hyperlights

Seems pretty equivalent:
v7 9.2" is 4.53 oz (M and U) and the new Smoke 10" is 4.6 oz (M) (at a total of 10.13")

v7 11" is 5.042(M) or 5.432 oz (U) and Smoke 12" is 5.1 oz (M) (at a total of 12.13")

So weight to length ratio seems pretty close as long as the eventual user data isn't much more than what Smoke is claiming. But V7 does have the advantage of a 1.13 oz barrel nut to smoke's 1.305 oz.

I wonder how much the optional CF rail on top adds to the weight.

Curious to get some thoughts:

I either have or are considering these parts:
1.) 16" BA hanson profile with .625 LoPro Gas Block (own)
2.) Smokes Carbon Fiber Buttstock, Short Pull Version (considering)
3.) v7 Titanium BCG (considering)
4.) Spring/Buffer (unknown)

I guess my concern is that do you think I'm going to have cycling issues with this setup?  Should I consider getting an adjustable gas block?  I've never owned one but just wondering ahead of time before I go through the hassle of putting together the rifle.

All my light weight builds with light weight reciprocating mass have adjustable gas. Your other option is to have a custom sized gas port drilled in the barrel to reduce the amount of gas. I don't know how much the V7 BCG weighs or what buffers / springs your using... but you use a heavier buffer you'll also be okay here.

Like Nada Nada said, absolutely get an adjustable gas block to go with it and dial it in.  I've built 2 rifles with Taccom's LW polymer buffers and used flat wire or 300 Blackout springs to great success.  I use the flat wire with a JP enterprises AL Ultra LW carrier with a syrac ordinance adjustable gas block. The one with the 300 Blackout spring in on a Superlative Arms adjustable gas piston system. Either way they work, just have to have the right spring for the system and barrel length/ gas position.  My piston gun didn't cycle well with a normal or flat wire spring, but once I put in the 300 Blackout one, it ran like a top! The other nice things about Taccom buffer is it as light as can be (unless you're breastroker) and affordable.

I like my smokes CF buttstock (I have the long pull because I'm tall with long ape-like arms ) it's solid even with the open buttstock design.  Either length of pull shouldn't effect your operation as I understand they make the tube the same length inside and is set for a carbine spring/buffer.

Hey breaststroker, or anyone really, have you guys actually shot your lightweight ar15’s yet?

I've got about 1200 rounds through mine.

Toy Build
All metal, super light weight cutting every thing I can. As the title says, more of a toy than anything else seeing how light I can make a AR while still maintaining my must haves on it.
Shot maybe 400 rounds through it. Currently it's in parts, I've scavenged from it for other builds mainly because there are lighter parts now I can/need to acquire to make this particular build lighter.

Suppressed SBR
Not so much a toy. A fighting gun, but still using as light of parts as I can, including a TBAC 5, V7 2055 receivers, for example. Total still under 5lbs, suppressed, with irons, red dot, light, etc....
Almost 1500 rounds through it.

2nd Suppressed SBR
Like the other, not a toy. Shorter, but heavier than the first. Built it because I was torn between compact and light. Uses an obscenely heavy Spikes supressor. (seriously spikes, need a titanium super light over the barrel). Uses BAD's Light Weight PDW receiver. With all the same necessary equipment for a fighting rifle, still under 6lbs.
900 rounds or so.

Long Range
Not a Toy. Grendel build as light of parts as I can muster. Under 6lbs with Delta P supresssor.
100 rounds so far.

Ya, I shoot em. I'd take my Supressed builds to a class if there was ever a class with all suppressed builds.

FYI
I got hold of a Fostech upper receiver with smoother finish. It weighs 4.5 oz

The rougher texture Fostech upper receiver weighs 5oz

both have a similar loose fit to a Cross Machine Tool ambi lower which can be dialed out mostly by using the lower adjustment screw under the grip area