Barrel Weight Differences 16" lightweight vs. 16" M4

I am looking to build a fairly lightweight AR for my son to use; the 16" midlength that I have is too heavy for him with the full 1" diameter under the handguards. I am going to go with the carbine length gas system but I don't know how heavy the different barrels are. I was all set to go for the lightweight profile from Del-Ton when they put the M4 style on sale. What is the weight difference between a lightweight and an M4? The only difference I can see is the end of the M4 has more material. I would think it would only be a few ounces.
Any information would be appreciated.

A 16" M4 vs a 16" Lw is a difference of 4.3 oz (about the weight of a Surefire G2). Add in that most of the weight difference is at the end of the barrel and it seems like more.

Between the two I much prefer the handling of the 16" LW; though you'll find either fairly light after that HBAR.

1/4 pound doesn't seem like much.
I looked at a Bushmaster two years ago that was very lightweight, but I don't know if it was an M4 or the lightweight barrel. I wish I would have paid attention, but I was only browsing at the time. I wasn't getting into it like now.

My other thought is to go with a 14.5" M4 barrel with permanent flash hider. I bet it would cut into that 4 oz difference a little bit. Plus I could use a bayonet later on if needed.

My favorite barrel length/profile is the 16" lightweight. As previously mentioned, the M4 barrel additional weight is out at the end so it's more noticeable.

I think the CMMG 14.5 Lightweight Mid-Length Barrel w/Permanent Hider found here is about the lightest thing your'e going to find. If I was building a uber-lightweight I'd use either that or the CMMG 14.5 Lightweight CAR w/Permanent Hider Barrel.

I like the look of that CMMG LW 14.5" middy. It has a lot of barrel turned down under the handguards. CMMG is too pricey for me right now.

I received my reply about chrome lined barrels on the special from Del-Ton, so I am very tempted to go with the 16" M4. It is $391 with a chrome lined barrel. That includes the BCG. I really like Del-Ton's products, so it is making it a hard decision. I almost sent for the Stag Arms M4 upper with ARMS 40 sight a month ago, but decided not to for whatever reason.

I can always get the M4 now and later switch uppers to LW if needed. Then I'll have a reason to buy another lower to build for the extra upper!

I'm really considering dropping a bundle on a CMMG upper. I have some questions, though.

I am liking the 14.5" lightweight barrels, but I don't know whether the midlength gas system has the same benefit on a 14.5" as on my 16". Is the midlength gas better, worse, or about the same as the carbine gas ona 14.5" barrel?

If the 1.5" difference in barrel length causes them to be about the same, I'd probably go with the carbine because it looks better with the shorter barrel.
If I go with the carbine, though, I am torn between the lightweight barrel and a standard M4 barrel. I like the authentic look of a 14.5" M4 over the 16" M4. I have seen some decent prices on a 14.5" m4 upper compared to the CMMG prices. I'm irritated that Del-Ton does not have the shorter M4 upper, I still could go M4 or LW 16" from them and save over $100.

I assume the loss of 1.5" on a 14.5" m4 would be within 2 oz of a 16" LW barrel?

I was going to buy the parts seperately, but I like that Del-Ton checks the headspace for me and test fires the upper.

HELP ME!!

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You're over-thinking this.

Ignore aesthetics and "looks better", that will help you alot right off the bat. Most of my rifles look goofy, but they work for me for the applications intended. Try to figure out what you're building this carbine for. Form follows function, and if you can determine the function you'll answer all of your own questions and the form will take care of itself.

Were it me? I'd order the 14.5" CMMG with F front sight base, M4 feedramps, and have them mount it on an M4 upper with a Daniel Defense 9.0 rail installed. That will give you the lightest possible setup with the best possible (for my) function.

Of course, if I was really doing this I'd mount the whole thing on a lower I SBRd and keep from having to permanently attach that flash suppressor, but that's just me.

ETA:
Actually, you're under-thinking this. Or wrong-thinking this. You're priorities are wrong when you talk about what looks cool.

Do I absolutely have to have M4 feed ramps?

The DD handguards are out, I'd be going standard handguards.

I have been tossing around the SBR idea, but if I go that route, I'm not wasting it on a measily 1.5" inches. I would buy a 10.5" upper in that case.

My main purpose is to have a gun for my son to use at the range that is fairly lightweight in case he stands and shoots. Mostly he uses the bench to shoot from. I would like it lighter than my 16" middy so that I can use it also standing. I find I cannot shoot too long freehand because of the weight. I thought of adding a bipod to the end of my middy for him to use on the bench, that would take the weight out of the equation for him. If I bought the 14.5" M4 or otherwise, I may use it for my home defense weapon and mount my EOTech on it. I would like to use a low profile gas block and go with a 12" FF handuard by MI or YHM, but I figure the weight may increase over the standard carbine handguards.

Weight is very important, but it doesn't have to be a superlight AR.
Looks are somewhat important, but I'm sure anything will grow on me. I love the look of my 16" middy, so the CMMG 16" lightweight is appealing.

Are DPMS uppers any good? I saw a 14.5" M4 upper for around $440 which is a decent price compared to the $575 that CMMG has.

Contact Grant and get one of the uppers he talked about here
https://www.m4carbine.net/showthread.php?t=3359&page=3