Where would be the most obvious place to shave weight from an assembled rifle? I've had my main shooter for years, when the 'recce' style first started. I'm looking at ditching my old DD rails for a slim mlok. Where else should I look to shave weight? I have a 16" heavy profile barrel, so that could be a future possibility. I have an Vltor stock, shaved gas block... any ideas?

Barrel.  Absolutely that barrel.

Change your barrel before ANYTHING else, then re-assess.

V7

check out all their light weight parts to waste money on :P

Barrel is really good idea - get a nice pencil barrel

I don't know why, but for some reason I'm worried about getting crap accuracy out of a new barrel. My existing one shoots very very well. But it's had a ton of rounds through it. Yall think it would be a noticeable difference?

Not as long as you buy a good barrel

Why not spend $150 to reprofile it of you love it

No surprise that a barrel is usually the biggest pig on a rifle. Next is a fat rail followed by a Magpul UBR.

This is a BIG part of your problem (and mine too...)

I have a HBAR 16 Rock River barrel that weighs in at a hefty 37.6oz. In comparison...my 18" odinworks SS barrel here:

https://www.odinworks.com/223_Wylde_Barrel_p/b-223-18-3g-rifle.htm

Weighed in at 34.3oz. (both stripped down bare)

A 16" like this one here:

https://www.primaryarms.com/Spikes_Tactical_Barrel_ST_14_5_M4_LE_Mid_Length_p/sb51405-lw.htm

Weighs in at 22oz. (not suggesting that is a good barrel...just picked the first lightweight 16" I could find).

That swap alone would shave damn near a pound...

I just gave up on it and decided it is what it is unless I buy a new barrel...like you said though...I'm getting great accuracy and superb reliability out o my current rig...not so sure I want to mess with that.

Get a KMR rail and a gov't profile or pencil barrel

"HBAR" is no guarantee of accuracy, it's just less work done profiling the barrel. If you got a good one it was more due to the maker doing the rifling correctly. Pick a pencil profile barrel from as good a source and it will be a pound lighter.

One pound off the muzzle end of the gun makes a huge difference in swing and how it handles.

Use of a lightweight tube for a reasonable price would be on the list, as much as a MFT Minimalist stock. Choice of optic comes in, a big milspec RDS vs a reflex. Last but not least - use 20 round mags, not 30's, at least for the first, and also because if you do need to shoot from the prone you are lower.

Much more than that, the costs become exponentially higher for less and less weight saved.

Having put a few builds I've done on a "diet", the barrel is where you "feel" most of your weight. Barrel profile is a lot less critical than people think it is with regards to accuracy, particularly within the context of a combat weapon. If you are thinking of buying a new barrel, take a good look at the dimensions of the barrel profile of what you're looking at. I've seen a few barrels that were called lightweight, but in reality were just A2 profile. The M16A1(and Colt SP1) had a barrel diameter of .625" at the gas block, with most of the rest being closer to between .585-.605". Contrary to what most people think, the only reason the military went to the heavier A2 profile was because knuckleheads were bending their barrels trying to open 55 gal drums. Obviously, that is not a concern in your case(I would hope at least).

I believe the HBAR profiles were something born out of the late 1980's- early 1990's. Demand for military type rifles spiked(much like it has in recent "panics")during this time because of all of the rise of the modern anti-gun movement and it's successes. So obviously, manufacturers were going to be looking for ways to increase production rates to meet the demand. an HBAR barrel requires almost half the machine time to turn from a blank as a lightweight A1 profile, because they are generally unprofiled (or profiled very little) under the handguards. This time savings is HUGE when you're trying to make 1000s of something, even more so when you're trying to make 1000s in a hurry. Interestingly enough, when did we start seeing HBAR rifles/carbines? The late 80's-early 90's; right at a point when demand was massive for ARs. Somehow I don't think this is a coincidence. And I'd bet that their introduction had a whole lot more to do with production than it did accuracy.

It may not sound like much, just looking at the dimension change, going from an HBAR to a A1 profile barrel. But the felt difference is HUGE. I had a ban era carbine a while ago that I did this too. It was an HBAR-completely unprofiled (so between .950-1.000")forward of the chamber until the gas block, and .750 forward of that. I turned down the whole barrel forward of the chamber, with the exception of the gas block(I didn't want to have to track down a .625 FSB) to A1 profile. The weight difference? Before I started it weighed more than 9 lbs loaded. When I was done, 6.5 lbs loaded. It felt like it didn't weigh anything at all in comparison to what it did before.

Now there is a tradeoff for this. Thinner barrels are obviously less rigid than thicker barrels are. So you could potentially get some vertical stringing as the barrel heats up. This occurs because of the extra "droop" in the thinner barrel. It's not really a big deal accuracy-wise unless you want a rifle that will shoot 1 MOA or under, even if it's hot. So you should really consider what you want from the rifle. If you want that kind of accuracy, you could still turn your barrel down, but I probably wouldn't take it down as far. You could also flute the barrel. If you're OK with potentially having combat accuracy(which in all seriousness is perfectly adequate for all but long range shooting beyond 600), in return for true light weight than I'd turn it down to A1 profile.

This thread is relevant to my interests, as my fiancé has told me she wants an AR, but it has to be lightweight. I already convinced her that letting me SBR it would shave off a lot of weight, so I'm going that route, but I've always been afraid of LW barrels heating up and throwing shots. Would a shorter barrel (say 11.5") be less prone to throwing strays when hot as compared to a 16"?