Ultralight Ultralight Rifles

Great to hear about the Green Mountain blanks. I think this is the best option for a 16+ inch straight-pull barrel. It'll cost a good chunk to machine it down, but it'll be done right. A chrome-lined GM barrel in a manually-operated ultralight should last multiple lifetimes. Good luck shooting one out.
 
Here's how my Ham'r's looking right now.

Essentially identical to it's .223 iteration, but with a shinier barrel. 20240702_180959.jpg
I added a couple of layers of 1" closed cell foam to the butt plate. I was finding the LOP short & I'm also expecting the .300 to have a little more thump. Oddly, it weighs over 1oz less than before, coming in at 4lb 2.2oz

I've dummy loaded a couple of rounds with 125gr TMKs, one as intended & 1 with a clipped tip. Both are loaded as long as the Lancer 300BLK mag will comfortably allow at 2.255"
20240702_180012.jpg
As you can see, with the tip intact the ogive is well into the case mouth. Abbreviated, it's perfect & at that length I have a 0.003" jump to the lands.
I'm really hoping to test out the clipped bullet on a hog or two before I attempt to slap one into a cow elk.
I've got a couple of hundred Speer 130s as backup though, just in case.
20240702_175907.jpg
Not as sexy to look at, but a proven bullet in the cartridge.
 
Thank you all for this thread. I can't believe it took me this long to discover it. I am intrigued. What a fun project. I built a bunch of lightweight ARs using the magnesium alloy receivers but lost interest when I moved to Florida and started hunting more. This looks awesome and gives me something to do in retirement. Ordered the upper and the carbon lower. I like the idea of a Sig MCX folder as my stock. I also want to have an adjustable stock on hand due to the number of youth and small statured people that like to visit and want to try out the range at my ranch or go hunting. I have a nice 9oz Leupold 3-9 VX-2 ultralight still on the shelf that I am glad I did not sell.

My one question is are there strong recommendations about a 16" .223/556 barrel that is lightweight and shoots the 77 gr TMKs well? Since it will be used to hunt our tiny Florida Whitetails, that is the round I would choose based on the .223 thread.
 
Tikka better watch out. Once we have a parts list for the "Gman Special," an ultralight SWFA 6x28mm Super Slender (SS) optic with 3/4-inch maintube, and a magnesium Unknown Munitions AR mount, who's gonna buy those Finnish anchors?

In all seriousness, it's hard to come up with a single parts list because every build is unique. The barrel is the biggest variable. There isn't an off-the-shelf offering, though Shaw or Wilson Combat are the best bets for a 16-inch, featherweight, gas-port-free barrel. That said, any 1:8-twist 5.56 or .223 Wylde barrel should produce fine accuracy with the 77 TMKs for deer hunting.
 
Liftman101 said:
Thank you all for this thread. I can't believe it took me this long to discover it. I am intrigued. What a fun project. I built a bunch of lightweight ARs using the magnesium alloy receivers but lost interest when I moved to Florida and started hunting more. This looks awesome and gives me something to do in retirement. Ordered the upper and the carbon lower. I like the idea of a Sig MCX folder as my stock. I also want to have an adjustable stock on hand due to the number of youth and small statured people that like to visit and want to try out the range at my ranch or go hunting. I have a nice 9oz Leupold 3-9 VX-2 ultralight still on the shelf that I am glad I did not sell.

My one question is are there strong recommendations about a 16" .223/556 barrel that is lightweight and shoots the 77 gr TMKs well? Since it will be used to hunt our tiny Florida Whitetails, that is the round I would choose based on the .223 thread.
Click to expand...
Both of the Faxon pencil barrels would be good bets. The Wilson Ultralight as well, and it's a bit lighter than the Faxons.

There are a couple of really cheap 1 in 7 barrels that are really light, but not many reports on them yet (Bear Creek Armory and the NBS Pencil barrel from AR15Discounts).

If you try either of the latter, a range report would be really helpful!

To add: As StupidLightweight mentioned, there's all kinds of options and directions you can take. The first two builds posted in this thread are good basic starting points, and both are pretty simple to do.
 
Thanks. The Wilson and the Faxon both show 19 ounces in their specifications and are 1:8 twist. The Bear Creek lightweight 5.56 is 1:7 twist but the specs say 24 ounces. It is on sale for $66 which is crazy.
 
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My Green Mountain barrels finally made it back from the fat farm. I used a Faxon pencil profile barrel as my guide. Sent them multiple pictures and measurements in an attempt to replicate those dimensions, just without the gas port. Had them trimmed to 16” and threaded 1/2-28. They look good. I’m happy with the weights. I have approximately $350 each invested in them now.
 

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FYI if you are considering going the green mountain route: I wish I’d thought to have them engraved with the chambering and twist. You should do that.

223 Wylde 1:7
 
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ebrownw2 said:
My Green Mountain barrels finally made it back from the fat farm. I used a Faxon pencil profile barrel as my guide. Sent them multiple pictures and measurements in an attempt to replicate those dimensions, just without the gas port. Had them trimmed to 16” and threaded 1/2-28. They look good. I’m happy with the weights. I have approximately $350 each invested in them now.
Click to expand...
Mind posting what you told them so I can plagiarize?
 
Does anyone have thoughts on a brass sleeve like this for the port? I guess I don't know the properties of brass enough to know its strength and so on.


Sleeve.png
 
180ls1 said:
Does anyone have thoughts on a brass sleeve like this for the port? I guess I don't know the properties of brass enough to know its strength and so on.


View attachment 732035
Click to expand...
I don't see why it wouldn't work.
The easy button is to run a #36 drill bit into the port, tap it to 6-32 (or 6-40 or 6-48) & slap a scope mounting screw in there. A spot of red loctite, file it flush & you're gas-tight.

It literally takes longer to type it than do it.
 
robtattoo said:
I don't see why it wouldn't work.
The easy button is to run a #36 drill bit into the port, tap it to 6-32 (or 6-40 or 6-48) & slap a scope mounting screw in there. A spot of red loctite, file it flush & you're gas-tight.

It literally takes longer to type it than do it.
Click to expand...
Rob, this is a great solution, but damn, you must be a slow typer!
 
StupidLightweight said:
For those interested, NFA has poly lowers on sale for $21 apiece. The discounted price shows up in the cart.
www.newfrontierarmory.com

LW-4 Stripped Polymer Lower

Discover the LW-4 Stripped Polymer Lower - the strongest and lightest lower receiver for your AR-15 build. Made with reinforced polymer, it's built to last. Buy now!
www.newfrontierarmory.com www.newfrontierarmory.com
Click to expand...
4.15oz.... wow. Is there any lighter lowers?
 
Thanks for all of the great information in this thread! Now I MUST build a rig lighter than my kimber rifle! Only took me 3 days to read and comprehend most of this thread, as I don't know much about AR's.

Anyhow, I'm new to AR's, so please help me with a few questions.

-large or small pin trigger for the Tennessee arms & NFA arms lowers? I couldn't find anything on their sites about this.
-good single stage 2lb ish trigger options under $100? Looks like CMC may have issues in the cold, so that's a nogo.
-how light did Gmans homebrewed stock and handgaurd end up shaving off?
-have LRI shave down my faxon barrel but then have to run a sleeve versus the set screw? Maybe save an ounce? I'm running suppressed, so removing any weight out there would really help the balance!
-are the 4x leupold fine cross crosshairs thick enough to see at 400 yards until the end of legal light?
-I really should have taken notes as I know I'm forgetting something!
 
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Trackselk said:
Thanks for all of the great information in this thread! Now I MUST build a rig lighter than my kimber rifle! Only took me 3 days to read and comprehend most of this thread, as I don't know much about AR's.

Anyhow, I'm new to AR's, so please help me with a few questions.

-large or small pin trigger for the Tennessee arms & NFA arms lowers? I couldn't find anything on their sites about this.
-good single stage 2lb ish trigger options under $100? Looks like CMC may have issues in the cold, so that's a nogo.
-how light did Gmans homebrewed stock and handgaurd end up shaving off?
-have LRI shave down my faxon barrel but then have to run a sleeve versus the set screw? Maybe save an ounce? I'm running suppressed, so removing any weight out there would really help the balance!
-are the 4x leupold fine cross crosshairs thick enough to see at 400 yards until the end of legal light?
-I really should have taken notes as I know I'm forgetting something!
Click to expand...
1.) Small pin like 99% of other ARs
2.) I am really enjoying my Rise Armament 140, on sale for $75 Here it is a “3.5 lb trigger”
3.) @Thegman ??
4.) If you have the money to burn, go for it and post your weight saving results! If I were to do it, I would just get the lightest blank and have a smith chamber/ar15 barrel extension. No gas port, thinking kimber pencil barrel thin/weight and stainless to boot. And it opens you up to caliber choices.
5.) I have no experience with the exact scope, I do have a vx2, 2-7x33 with duplex, and have shot it a ways further than 400 yards, not on an ultralight though.
 
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