In my experience, that has always been the case. Miniaturization and light weight have always come at a premium across pretty much all industries.

But yeah, I get we all don't have a F1 budget to mess around with an infinite amount of variables to get that perfect combination.

I think weight is actually one of the biggest drivers in the retro craze. Guys get behind a pencil barrel gun with nothing bolted on to it and it’s an entirely different experience.

One of the big training places just posted a video on insta (forget who) but the dude is huge and has a rifle with about everything you can think of bolted to it. The guy was beat down and you could tell he was done shooting for the day.

Bringing a heavy rifle to your eye isn’t hard. Doing it the hundredth time is.

Its true, alll my retros, to me, feel super light.

I think balance plays a bigger part than it gets credit for. I've honestly never weighed any of my guns. Never cared. I don't think a scale should be a deciding factor, unless it's a "fun gun" where the numbers are a goal. I don't hang a bunch of stupid crap off my guns, but an optic, light and sling contribute the the weight. Add in a can and it's even more so. My normal, most used gun is an SBR with all of the things mentioned above. I'm sure for being an 11.5 the scale would look off, but all that shit adds weight. It's not heavy though and balances naturally. You don't even notice the can (and we're not talking a ti one). It just feels right. Point being, set up a defensive gun as such. It doesn't need to be 6lbs (or 7 or whatever). It needs to be reliable, have what you need and have a good, centered feel to it. It's easy to get too wrapped up in a vision and miss what actually makes sense for the application. Also easy to go stupid heavy and nose heavy, but 8 pounds that caries it towards the rear actually handles pretty well.

You should toss your rifles and everything on a scale then just for the hell of it. What cans do you run? Looking back, I wish I went with a lighter weight can but it is what it is at this point

I got a new scale & weighed the optics again

The PA 3x micro showed 8.96 oz
The PA 5x micro w/piggy back mount & mini reflex dot showed 12.52 oz

I think that’s pretty dang reasonable.

Let's see how much it goes down when I install the ADM mount

lol, you made my go weigh mine.

PA 3x (by itself w/ARD & Butler Creek cap): 6.75 oz
PA mount I was using: 3.25 oz
LT105 QD mount (that I'm using now): 2.25 oz

And just as an example of compromising...

My favorite, handiest, most fun AR weighs 5.5 lbs (with above optic).

BBUUUTTTTT, it doesn't have a sling, WML or irons/BUIS, etc.
Oh, and it's a 9" 22LR RTB upper.

My HD 10.3" SBR weighs almost 8.5 lbs., but I wouldn't change anything on it. Mission first.

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If you start reducing weight towards the rear of the rifle it’s going to make it worse, especially with a can on the end.

I dont have a scale. Never really cared, but you have me kind of curious. Maybe I'll grab one and check. Can is a recce 5. By far not the lightest thing out there, but my set up doesn't feel muzzle heavy at all. It's very neutral feeling. At least to me, that's much more importeant than overall weight.

I have an under 5 pound 8oz AR with optic, BUIS, and weaponlight.

It has a JP LMOS carrier and Titanium adjustable gas block.
It has a Faxon pencil barrel.
It has a magnesium rail.
Every part that can be V7 ultralight is... bolt catch, safety, castle nut, end plate, cam pin, firing pin, trigger pins, buffer retainer, etc. ALL the parts.
The optic is a T1, no magnifier. The BUIS are the new lighter MBUS and it has no silencer, just a titanium flash hider.

Without going this route, you wont get 6 pounds with magnified optic, BUIS, and weapon light.

It is very reliable and I even use the same JP LMOS carrier on my duty rifle (the ultralight is NOT my duty rifle), but I wont go any lighter in the carrier, especially suppressed.

You won't get to add magnification and a silencer to your build and stay under 7 pounds.

My ultralight is set up for a female or child to use. It has extended mag release, non beavertail grip, 45 degree titanium/aluminum safety, etc.

There are limits to what can be done and where weight can be cut. A pencil Faxon and magnesium rail are not ideal for a SHTF build. You have a very weight optimized build. You can save a little by going with a titanium adjustable gas block, LMOS carrier, and 3oz buffer but going lighter may have a negative impact on reliability. The above combination of parts will not in my experience. Even suppressed.

I built an almost identical 16" precision rifle with 26oz barrel and V7 2099 lightweight rail. It weighs 6 pounds with no optic, light, or BUIS. The difference was just a slightly longer/heavier rail, heavier stock, .750" gas block, an ASR flash hider suppressor mount, a BCM grip, and the barrel weight.

Be happy with what you have. If you go adjustable gas block and lighter carrier, don't go crazy on carrier weight and not expect to be VERY overgassed suppressed.  Stay away from titanium/aluminum carriers.

Aluminum carriers are a known wear item that must be replaced.  Titanium carriers are as strong as steel but lighter weight, not as light weight as an aluminum one.

I never said under 7 with can. ;)

I broke the rifle in yesterday and am happy with it. I can always build another & see how light I can get based on my needs

https://www.ar15.com/forums/AR-15/Lightweight-Parts-List-with-WEIGHTS-AR-15-/118-638524/

I have come to the concussion that LW AR15’s don’t exist if you want to build a “hunting

https://pof-usa.com/firearm/rogue/

& this is part of why I love my A1 clone(-ish, anyway), as well as why I want to build a 14.7"+P/W early RO723 clone.

I love shooting from a bipod lol

I am reminded of the old Hot Rodding adage:

"You can have it fast.
You can have it reliable.  
You can have it cheap.
Pick any two"

Same applies to guns.

My lightest build uses a Faxon Gunner barrel and Lightweight Carrier.  But after a while, and a lot of time and money swapping parts, the return on investment for chasing the last few ounces wasn't paying out for me.  So I finally decided to be happy where it was at.  YMMV.  Physics is still physics.  The heaviest parts of the AR platform are the most important parts of the AR platform.  When you compromise them to save weight you will eventually reach a point where you also compromise life span and reliability.

OP:  I second using the lightweight parts database and the associated thread.  It's a great source of info and I used it when I did my lightweight build, which is NOT a SHTF gun namely because it has a polymer lower, but it's just over 5 lbs with a red dot and backup sights.

But to reiterate what others have said, lightweight is gonna cost you a premium, if its an aluminum part that means there was more machining time involved, if it's carbon fiber or titanium then also more time and material costs.  All that being said here are some of my parts recommendations based on my own builds.

Carbon fiber buttstocks, namely from Smoke Composites are light and strong, but generally non-adjustable. https://www.smokecomposites.com/stocks
If you want to go adjustable I recommend the Roger's Super Stock (sold under a few different brands) but it's what I have on my SHTF gun, it's light and strong but has a locking cam so you don't get any wobble once you have it where you want it, and both QD and sling loop points.  I'd recommend it over a basic CAR stock.

Smoke Composites also have CF handguards but I didn't buy theirs.  I had gotten Troy CF octagonal handguards for one rifle (no longer produced) and a tubular CF from another CF handguard company that went out of business in the mid 2010's, but it has been rock solid on my lightweight rifle. . I have also gone with TacStar's carbon fiber handguards which are decent on a .300 Blackout pistol and been very happy with it.  https://www.opticsplanet.com/tacstar-carbon-fiber-ar-15-handguard.html
Now days I'd say Faxon, Brigand Arms and Lancer are also well known for quality Carbon Fiber handguards.

As for BCG, assuming your going DI and not piston, then get something that's as slick as possible, I've drooled over Cryptic Coatings Mystic Black for forever and every reviewer as said it cleans off very easily. They make them in Titanium as well as steel, but the Ti's are almost always out of stock and just about double the price, though lighter.  https://www.crypticcoatings.com/product-category/bolt-carrier-groups/01/  I have the JP ULMOS BCG paired with a couple of Taccom polymer buffers in my super lightweight, but I don't recommend that combo as on plinking ammo it doesn't always have enough umph to cycle a new round.  I'd stick to a heavier buffer for reliability.  Whatever carrier you do get, tune it with a buffer and spring to suit your ammo.

Finally barrels wise, pencils are nice to save weight, but I prefer the Faxon Gunner that I used on my own lightweight build (did I mention it is an 18'' barrel and yet still managed to get it all under 5 lbs before optics?). It's a good compromise between light weight and a bit more barrel stiffness.   Otherwise see if you can find a carbon fiber wrapped barrel; pound for pound they have the best barrel stiffness, and the one I do have on my SHTF gun and it shoots like a laser- fantastic. (But costs 2-3 times more than a high quality steel barrel).

There are plenty of other small parts to shave off ounces, TI or Aluminum castle nuts, TI pins, screws even barrel nuts.

Hope all this is helpful and have fun working towards your goal with your build.

All good points, thanks. I did base part of my build off that database. There were just certain things that I was not willing to change plus I was not going to end up spending thousands more than I did.

I knew it was never going to be "lightweight" I was just hoping to build something lighter. Do I wish it were lighter than it is? Yes, but not wishing enough to spend a bunch more $ than I already have. I knew it was going to be "heavy" after I put the can on it anyway.

I do have the Faxon Gunner barrel in another AR (16") and am happy with it. Wanted to try out one of the barrels that lots rave about. No regrets on the Centurion. It's only 4 oz heavier than the Faxon and I shot at least 1 MOA with it 1st time out once the optic was sighted in.

Exactly where my head is at. You are 100% correct

this

the only goofy weight/balance rifle I assembled was also the lightest.  it balanced about 1.5" in front of the magwell. it was also over 1lb lighter than my favorite rifle.  an ar needs to balance within the magwell, preferably about in the middle.  otherwise it feels front heavy.