This is going to document my attempt at MY lightest AR15 possible.

Why you ask?…. Why not!

Salad days are here, parts are in stock and cheap everywhere. I had a spare lower that was begging to be built. I already have multiple other types of AR. heavy 20” “long range” gun, 300 blackouts. “Combat" style yada yada yada.

Worst case scenario is when Hilary is in the running for the white house another panic will hit and I will double if not triple my investment.

My basic rules for the build.

No polymer uppers or lowers! Personal preference.
Must be reliable. What good is a gun that does not shoot!
I am not going to dremel and drill the shit out of everything to save weight. Weight is the number one priority but I do not want it look like a 5 year got ahold of it in front of drill press.
Last it must have a collapsable stock. I like having the option to allow adjust the rifle to the shooter. I have seen many many lightweight builds that have an ugly fixed stock tube that looks like the arm of a chair.

So I started with a standard Rock river lower that I owned.

Lower build:

ALG trigger
v7 titanium parts:
   castle nut, endplate, grip screw, buffer retainer, safety, trigger/hammer pins, bolt catch (not in yet), magazine release
2A hollow titanium takedown pins
Carbine buffer
carbine spring
standard mil spec buffer tube
Minimalist Stock
Magpul MOE-k grip
Magpul Moe polymer trigger guard

i am hoping to save .5lb with all the titanium lower parts compared to standard mil spec parts. Yes with the extra $200-$250 price tag. Pretty expensive for  .5lb but…. Titanium is awesome and when you get down to the final ounces in weight savings, nothing is cheap.

I will weigh all small parts with my Frankford Arsenal digital scale I use for reloading since it can give me grams to X.XXX digits

****Springs, roll pins and detents not weighed because I do not think there are light weight options, so no comparison *******


The first titanium part I received were the 2a arms titanium take down pins. I chose them because of there hollow design as well as still sitting flush with the receiver and not sticking out extended version. This is just a preference.

Very cool looking

Front pin 3.625g
rear pin 2.535

total of 6.160g

standard front pin 8.260g
standard rear pin 5.910g

total of 14.170g

*****Savings 8.01 g*****


standard buffer retainer 1.960
V7 Titanium buffer retainer 1.095

*****Savings .865g*****

standard castle nut 16.790
standard end plate (non QD) 14.54 (both combined 31.330)

V7 titanium castle nut 9.660
V7 titanium QD endplate 7.810
both combined 17.470

*****Savings 13.86g*****

standard mag catch and button 10.715
V7 Ultralite mag catch and button4.785

*****savings 5.93g*****

standard safety 16.165
V7 titanium safety (non Ambi) 9.120

***** savings 7.045g*****


standard pistol grip screw 8.065
V7 titanium pistol grip screw 3.105

****savings of 4.96g*****


Standard trigger and hammer .154 pins 4.080
V7 Titanium Trigger and hammer pins 2.320

*****Savings 1.76g******

standard a2 pistol grip 70.0
magpul moe-k 63.0

*****savings 7.0g******

Small edit. saved a couple extra grams with my trigger guard too

standard magpul polymer lower trigger guard with three 6-32 button head screws 6.525g
Skeletonized magpul polymer trigger guard and titanium 6-32 button head tor screws 4.140g
standard a2 trigger guard and roll pin 5.050g

*****Savings 2.385g*****

*****Savings of  51.815g******

So in the end a couple hundred bucks for a 1.828oz weight savings in the lower…. not much savings and expensive. Parts look cool though. fit and fish was awesome. I wish the magazine catch in titanium was as light as the ultra lite version I bought. I saved a couple extra grams but I do like the titanium color.

the complete lower with stock, spring and buffer came in at

Final complete Lower weight 29.45oz or 836g or 1.844lb

for comparison a standard lower with mil spec parts and a CTR stock came in at 36.30oz and my Larue lower with complete came in at 40.30oz










waaaaay more weight savings will come in the upper. please stayed tuned. 14.5" pencil barrel, titanium flash hider, titanium gas block, balios lite upper, BCM KMR rail with titanium barrel nut. v7 charging handle


BCG is yet to be determined

boomfab titanium

Nice. It's cool to see people pushing the limits

wonder how much that color fill weighs

DAMN! that is nice. my whole concern right now is the  cycling issue. midlength gas system, and non adjjusable block (as of now) and standard buffer and spring

Built a rifle for a guy similar to what ur doing. Mag tech upper and lower. BCM Kmart rail, all kinds of titanium shit. 14.5 pencil bbl. mid gas, you will need an adjustable gas block to get it to cycle right. His rifle without optics came in at 4 lbs 5oz. Could have save some weight with the boomfab. But he had a youngs ultralight that he wanted to use.

And you're not using a 2A Armament receiver set why?

They are at a good price here

Battle arms tube and stock?

Oop! NVM. "Must be collapsible".

I suggest this as well. Why not collapsible?
Love the Ti builds. get an adj gas block and the boomfab.

Yep. There's a ton of weight savings in a lightweight receiver set, more bang for your buck than the v7 stuff.

That'll only save about 2-1/2 ounces vs. a standard forged lower and a LW forged upper (w/deflector, no FA or DC).  Trust me, I've tried; there's just only so much material you can remove and still have a durable piece, and those little bits of of aluminum don't add up to a whole lot.

A Mag tactical set would save more weight.  A Mag tactical upper and poly lower is about the lightest combination (I won't do poly uppers).

The primary focus of weight savings needs to be on larger steel parts; either minimal, or replaced by aluminum and titanium.

And while I really like titanium, for maximum weight reduction, aluminum or magnesium alloys should be used wherever possible.

Weights by cubic foot:

Mg: 108 lbs
Al: 168 lbs
Ti: 283 lbs
Steel: 490 lbs

I am going to be using a bailos lite upper.

the reason I went with  this lower is because I already had it, and I am behind CA lines and this is  "registered"  so I can use standard capacity mags and a standard magazine release.

A Boomfab titainium carrier for that build would be nice. But with any lightweight carrier, you'll need an adjustable gas block to run it safely. SLR or Syrac makes good adjustable gas blocks.

However, if you want to keep the titanium gas block, you'll have to run a standard BCG, or the Rubber City Armory regulated carrier/key. 2A Arms is suppose to come out with a LW adjustable carrier too.

Not necessarily.

I carved 2.6 oz off this carrier:



And the rifle, which weighs 4.87 lbs (including the flip-up sights and the MS-04 on my custom mount) runs flawlessly, with a pretty mild recoil impulse.  I am running a standard carbine buffer & spring with a non-adjustable aluminum GB.  We even ran the upper (with my LW carrier) on an M-16 lower that had an H2 buffer.  Not one hiccup.

Are you planning to use an optic? I ask because i recently got rid of the qd mount for my Aimpoint micro and went with the Fortis F1 absolute cowitness cantilever mount, and the total combined weight is a mere 4.1 oz. I wasn't going for as light weight as you're going, but wanted to avoid ending up with a cinder block. I too went with the minimalist stock w/o paracord and a 13" KMR. Best of luck with the remainder of the build. Looks great so far.

True, not necessarily. But the gas port size, BCG weight, and buffer/spring all have to get along. When you remove weight from the carrier, it's usually a good idea to add a heavier buffer, or adjust the gas. So if your setup runs with an standard buffer, it should work even better on that M16 lower with the H2 buffer.

Either way, it is recommended to "tune" the system when changing a component, especially if going with lightweight parts. You don't want the carrier banging into the receiver.

Better how?  The rifle hasn't missed a beat.  I'm not trying to be argumentative, just saying that it'd be hard to improve on 100% reliable cycling and LRBHO.  It actually ran fine with an empty buffer, too, although the recoil impulse was noticeably more violent, and long term durability of the poly lower with a harsh impulse led me to decide that dropping 2 more oz wasn't worth it.  I may see if I can get it to a happy spot with an empty buffer and an adjustable GB down the road, but 2 oz on the ass end is not the least bit bothersome anyway.



Correct.  Standing in contrast to this featherweight that worked out beautifully, my wife's rifle, a 16" gun with carbine gas, has a rather large port, and produces quite sharp recoil with a standard buffer, even running a full weight M-16 BCG.  It was noticeably harsher than the featherweight, despite being nearly 2 lbs heavier.  You could tell the buffer bumper was slamming into the rear of the RE quite forcefully.  That rifle needs an H2 to feel "right".



Agreed, though unless you remove the bumper on your buffer or run a carbine length buffer in a rifle tube, this should never be able to happen.  

I go off of reliability first, recoil impulse second.

yeah, the lightweight BCG,buffer,spring,gas system and gas block are new territory for me. i have never used LW BCGs before.

Just trying to wrap my head around the system.

If you go with a super light BCG and standard buffer would you need less gas to cycle properly?

Also would a carbine or mid length gas system be better with a LW BCG and standard buffer?

Extreme lightweight build:

http://www.ar15.com/forums/t_3_4/653416_Xtremely_Lightweight_build.html

Better as in a smoother and less violent action/recoil impulse.

Reducing the reciprocating mass, will require less gas to run it, so if you don't adjust the gas, it'll be "over gassed".

Feeling the buffer bumper hitting the end of the receiver extension forceably is not a good thing. Generally, a 16" carbine is over gassed, so most run a H or H2 buffer, to smooth it out a bit.

3 gunners and the folks who use LW carriers usually run an adjustable gas block with a super light buffer, taking advantage of the system as a whole, and tuning down the gas.

Not saying that an AR with a LW carrier/buffer can't be reliable, but the common recipe for a reliable AR is to run a M16 FA BCG, in a carbine length with a H/H2 buffer, or a mid length with a car/H buffer.

My SHTF gun has a BCM BCG, H buffer, and pinned gas block. I'm in the process of building a LW 3 gun upper, and it'll have a SLR adjustable gas block, RCA LW carrier, and probably the Taccom ULW buffer.

OP, nice list of parts, and I look forward to part 2. Oh, and I am definitely jelly of your RAW!

I think you misunderstand.  My 14.5" LW with carbine buffer is smooth and soft; it was only sharp when I tried an empty buffer.  The 16" with carbine gas is a completely different rifle.

I'm calling BS on this.

You MUST look at the carrier and buffer as one and the same unit. You look at TOTAL weight because they function as a single unit.

On my ALUMINUM carrier I'm running a 2.9 oz. buffer with no issues (and have been for over THREE DECADES). There are "tricks" you learn in tuning the system. I'm running a Wolff XP action spring which results in reliable feeding AND requires more gas to reliably cycle.

You quote me but kind of take it out of context; read the rest of my post please.

But no, I did not misunderstand. I know you are talking about 2 different guns. Your 14.5" LW on the M16 lower with the H2 ran 100% correct? Did you notice it was slightly smoother and less violent when compared to running the carbine buffer?

When you remove mass from the reciprocating action, it's usually a good idea to tune the gas system with an adjustable gas block, or use a heavier buffer to balance it out (weight vs pressure). Telling people that it's OK to run a LW carrier and that it'll be 100% reliable is probably asking for trouble. It's better to be on the safe side. I'm sure lots of people will agree with me.

BS on what?

I am saying to treat the system as a whole (gas port, BCG, and buffer/spring). You're running a LW carrier, with a standard buffer, and XP spring. You're tuning it with the spring and balancing out the weight and pressure/force.

Sixty is running a LW carrier with standard buffer and spring. So generally, we can say his gun is probably over gassed and more violent, when compared to the same gun with a tuned gas system or heavier buffer.

3 gunners run a LW carrier, LW buffer and reduced power spring, and tune it so the action is super smooth.

Look guys. Theres a "new" guy asking about LW carriers and whatnot, and you guys are basically saying its ok to change stuff without thinking of the system as a whole.

Sixty says his 14.5" with LW carrier and car buffer runs fine and smooth, but he did try a car buffer without the weights. Also, wouldn't the over gassed 16" carbine benefit from a heavier buffer? In both cases, isn't that what we call "tuning"?

Pursuit, you say you didnt tune the gas system when running an aluminum carrier, but you did use a XP spring. Doesn't that count as tuning the system?

All Im saying is, when removing or reducing mass from the reciprocating action, its usually a good idea to tune the system. Balance it out with a lighter/heavier buffer, weaker/stronger action spring, or adjust the gas with an adjustable gas block.

The gas port (and pressure), BCG weight, buffer weight, and spring strength, all have to get along.

Not really.  Honestly, it surprised me how gentle the thing is with the carbine buffer.  I fully expected it to be rather jumpy, as it was with an empty buffer.  With the carbine buffer, it shoots just as smooth as my 6-1/2 pound middy.

So with your LW carrier, going from a lighter empty buffer to a heavier carbine buffer, did help smooth it out, correct?

OP,

Awesome build so far! Looking forward to the rest of it. I'm also planning out a LW build and have looked into quite a few parts, here's a couple if you haven't seen them already:

JP - Alum BCG
http://jprifles.com/1.4.7_LMOS.php?menu_select=ALLMOS

Whiskey Arms Alum. BCG
http://whiskeyarms.com/products/lbc

And SLR is working on a titanium adjustable gas block but no word when it will be available, see this post.

And we have ANOTHER convert!

Glad you tried it out.

Correct.

I'm certainly not saying that buffer weight and buffer/BCG combined weight don't matter.  Just stating that sometimes more weight doesn't make any real difference in function or feel.  For this rifle, clearly, the lightened BCG with carbine buffer is minimum reciprocating mass without adjusting the gas flow.  But going heavier didn't make it run smoother or recoil more gently to any noticeable degree.  

One should definitely play with buffer weights if they feel that their rifle's recoil impulse is too harsh, or, conversely, if the rifle is having issues with stripping & chambering rounds or locking back on empty.  IMO, the lightest combination that gives a pleasant recoil impulse and allows the rifle to function 100% is ideal.



I think I missed something.  What did I convert to?

Nice! I know people that spent that on a whole rifle

Ok so it looks like I will go with a LW BCG and get an adjustable gas block, I don't want to run anything heavier than a standard carbine buffer, defeats the purpose of my build plus spending extra money to save weight with the BCG just to add it back with the buffer seems like a waste of funds.

My only question to you guys that have experience tuning a LW system....

Is it easier to use a carbine length gas or mid length gas system barrel? I have pencil barrels in each

Entirely dependent on barrel length.  

7-9.5, pistol.  
10-14.5,  carbine
14.7-18, mid.  
over, 18, rifle.

Yep.




It depends on the barrels' gas port hole size. But generally, carbines are a bit more gassed than mids, however, with an adjustable gas block, it doesn't really matter.

Another thing to consider is that the carbine length's gas block is closer to the receiver, so it'll feel slightly better balanced than a mid. But if you have a long rail, it might be hard to reach the carbine's gas block with a hex wrench.

You have the common sense to try something that MANY members say won't/can't work. And it does work.

What I refered to was another convert understanding that a lightweight carrier/buffer CAN be reliable.

Common sense? Understanding? Haha.

So, for 100% reliability, what BCG/buffer do you guys run in your HD/SHTF gun(s)?

I never said that a LW carrier and car buffer won't/can't work, nor have I said that it couldn't be reliable. Read all of my posts please.

3 gunners have used LW carriers with thousands of rounds fired, so it could be reliable, but I bet most (if not all) tuned their setup.

All I said was (broken record here) when changing the mass of a reciprocating action, it's usually a good idea to tune the system. Treating the gas port hole size, gas pressure, BCG weight, buffer weight, and spring strength, as a whole. Balancing all of it out with an adjustable gas block, adjustable carrier/key, heavier/lighter buffer, stronger/weaker action spring, or any of the other tricks you learned.

Sixty went from a lighter empty buffer to a heavier car buffer.

Pursuit is using a XP spring.

TZL is turning down the gas with an adjustable carrier/key.

Don't all that count as tuning?

The OP wanted to use a LW carrier. And you guys would blindly say it's ok to run it without telling him that there might be some tuning required? You guys tuned your setup, why shouldnt the OP tune his setup?

A little update, lower in damn near complete. Just waiting on an ultra lite bolt catch to come in.

The parts for the upper are coming in soon.

Stripped balios lite upper
V7 extended titanium flash hider
V7 charging handle

I have a 16" Daniel defense carbine pencil barrel and I am waiting on a 16" Faxon mid-length pencil barrel also. I have a place local that can do a cut down and rethread to 14.5"

I am leaning toward the faxon for the mid length system.

Need to order a .625" adjustable gas block
10" BCM KMR rail

Need to return the v7 titanium gas block

All your posts and advise in the thread are spot on.

Lightening weight (Buffer and/or BCG) or decreasing spring tension or increasing backpressure (suppressor) will increase cycle speed and increase perceived recoil by marginal amounts.  Just doing one of those will result in small change that that may not big deal to shooter.  While the LW carrier in this thread is being used to reduce weight of the rifle, most people are using them in competition guns, where you run a light buffer and low mass BCG and turn the gas down to where it will has just enough gas to function.



You can run the empty buffer with a adjustable gas system and when you restrict the gas the recoil will decrease.  There are lot of choices with adjustable gas blocks, the basic Micro Moa block is cheap (predrilled at .043) in your case you can just keep opening up the hole until it cycles correctly.  Also the adjustable gas key don't add any weight.

Small upper build update, some parts came in today

Different weights for uppers

Standard upper 247g (couple with FA and ejection door)
slickside 189g
Balios Lite 165g

a whopping savings of 82 grams (2.892 oz) with the Balios lite!

I have two choices for my barrel

I have a 16" Daniel Defense carbine length Pencil barrel 625g (22.0 oz)

and a Faxon 16" midlength pencil barrel 542g (19.1oz)

I am leaning toward the Faxon barrel due to the extra weight savings as well as the mid length gas system.

I will also cut down the barrel to 14.5" and add a titanium flash hider.

Thanks for looking guys and thanks for the schooling on LW BCGs and gas blocks etc etc.

Why cut down their 16" mid pencil when you can buy this?

Faxon 14.5 mid gas pencil barrel

Good point, I have already spoke about this with another member here as well as a rep of faxon. I was going to cut it because it was in my hand. I got a sweet deal on the barrel so it was in my hand. I live locally to a very reputable gun guy who does tons of barrel work. So to me it would be easy.

But then I got to thinking about the build plus the warranty of the barrel.

I made the decision a couple hours ago to sell both barrels and get the factory faxon 14.5.

The only hiccup is the faxon rep said it would be a while before they get them back

https://www.shepherdfirearms.com/index.php?route=product/product&path=59&product_id=62



https://www.shepherdfirearms.com/index.php?route=product/product&path=59&product_id=52









 

I'm a big Ti fan, but let's be honest about what it is and isn't.  Such as:



I wouldn't call a 68% increase over 7075-T6 "minimal".

You use Ti where you need the strength and/or higher melting point of good steel alloys with less weight than steel.  You don't replace aluminum parts that are more than strong enough for the application with a heavier and far more expensive material unless you're doing it just to do it, as I did with my carbon steel lower build.  

With that thing, you're paying an extra $1,100 for cool factor.  Then again, this company is trying to sell stripped uppers for $300.  Guess their target market is people with more money than sense.......

Yes i agree 100% with everything you said.



 

Just landed a 10" kmr rail from a member here for an amazing price.

So I just ordered a v7 titanium barrel nut to go with it.

Also ordered a 14.5" faxon pencil barrel and sold both 16" barrels I had.

This build is going 100mph!

I just crunched some published weights for parts and I could get this upper in VERY light!