Ultralight Ar15 build

shrxfn · Jul 3, 2017

On the 6.8 forum I am on there is a guy that is in to building ultra light rifles. Might give you some ideas.

Here is his 3lb AR15 build thread.

http://68forums.com/forums/showthread.php?60338-Ultra-Lite-All-Polymer-AR-556

Also has a ~4.5lb AR10 build thread as well.

http://68forums.com/forums/showthread.php?95633-Lightest-AR-308-71-75-ounces-or-4-48-pounds

Enjoy.

KDerekT83 · Jul 5, 2017

damn. I'd guess he made himself a challenging hobby within a hobby....

jdindadell · Mar 7, 2018

shrxfn said:
On the 6.8 forum I am on there is a guy that is in to building ultra light rifles. Might give you some ideas.

Here is his 3lb AR15 build thread.

http://68forums.com/forums/showthread.php?60338-Ultra-Lite-All-Polymer-AR-556

Also has a ~4.5lb AR10 build thread as well.

http://68forums.com/forums/showthread.php?95633-Lightest-AR-308-71-75-ounces-or-4-48-pounds

Enjoy.

Great reads there, many thanks for the links.

A lot of the good info seems to be hidden in various threads on other forums.

As an update I did get a magnesium lower and I do like it!

Turned my "god knows who" brand 14.5" carbine length barrel down to a profile that approximates the faxon profile of the 14.5 middy that I bought. Sticking with the carbine length port barrel as it lets me run a shorter handguard, so lighter. This pulled about 5 ounces off, amazing!

Also did some crazy work on the buffer tube, tuned the exposed section down to the same wall thickness as a std m4 collapsible tube. Where the brace touches I left 3 large rings for support, and then did some longitudinal milling to remove excess weight. End result, it now weighs the same as a std m4 buffer tube. So there may be more material to remove, I will keep an eye on that.

Currently I am at 4.17 lbs. I think I can get down to 4lbs with an optic. This will be an all metal build, only plastic is the brace right now.

Plus I am trying to keep the cost way down. I am at 575 right now. So pretty good. I am not factoring in the machine work cost, as I am doing that myself.

Dan6726 · Mar 24, 2018

Hey jdindadell, I’ve got a pof pre bushmaster also. If you don’t mind I’d like to ask you a few questions about this particular weapon.

DaSouthernYankee · Mar 24, 2018

Managed to find another part for y'all to use, link below. Its a low mass carrier, should shave off another 2-2.5 oz if you dont jave one in already.

NOTE THIS IS THE CARRIER ONLY so you need a bolt if you dont have one. I just ordered one for my lightweight pistol build, will bring me to 5 lbs 10oz or so with a full size red dot and BUIS, no mag. Also no brace as of yet either.

https://www.righttobear.com/RTB-AR15-Lightweight-Carrier-Black-Nitride-carr-p/sbn16-lw-co.htm

Sent from my LG-H918 using Tapatalk

jdindadell · Mar 25, 2018

Picked up a polymer lpk from new frontier. I have a spare magnesium lower so i will install the poly parts and see the weight savings. Not sure if i will stick with a full poly lpk though.

Now i am looking for the lightest red dot. I have a few options but if anyone is aware of a list or other info on optic weights i am all ears!

LACamper · Mar 25, 2018

Thanks for the update!

I still want to build an ultralight one of these days...

jdindadell · Mar 25, 2018

LACamper said:
Thanks for the update!

I still want to build an ultralight one of these days...

I plan to do a sister build of sorts. Only off the shelf parts without any mods to them. Just to see what kind of weight could be achieved by just making good choices when purchasing.

It will not be a "money is no object" build, all choices will consider weight and cost.

LACamper · Mar 26, 2018

That more what I had in mind.

DaSouthernYankee · Mar 26, 2018

Oh one more part for y'all that im using on my spr is the old school CAR style stock, Model1Sales has them i think. Its is 1.5 oz or so lighter than the MFT minimalist. Not as "tacticool" looking and it rattles some butits the lightest stock I know of and only about $25.

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jdindadell · Mar 26, 2018

DaSouthernYankee said:
Oh one more part for y'all that im using on my spr is the old school CAR style stock, Model1Sales has them i think. Its is 1.5 oz or so lighter than the MFT minimalist. Not as "tacticool" looking and it rattles some butits the lightest stock I know of and only about $25.

Sent from my LG-H918 using Tapatalk

I just weighed the kak shockwave with the kak tube, no hardware (endplate and castle nut) against a std m4 tube with the MFT stock, no hardware.

The weigh the same, and I know that the std kak tube is heavier than a M4 tube, as my heavily machined KAK tube is now the same weight as a std m4 tube.

So the KAK blade brace is considerably lighter than a MFT stock. Since you mentioned the OG CAR stock is lighter I will have to see if I have one laying around I can check. I was planning to lighten a MFT minimalist stock and a std m4 tube anyways, as my other lightweight build might as well be a true carbine and not a pistol.

I also have my eye on the a3 brace from SB Tactical. Would like to get a real world weight on it and the proprietary tube it ships with. Anyone know if that info is out there?

And I put the new frontier poly lpk in, that dropped it to 3.9 lbs!!! WoooHooo, getting there!

jdindadell · Mar 26, 2018

Current pic.

Everything silver is raw metal. I will have to coat everything in something when I am finished with test firing. That sentence makes me sound very committed.

leadslinger972 · Mar 26, 2018

You could shave a lot of weight if that barrel were six inches shorter.

DaSouthernYankee · Mar 26, 2018

leadslinger972 said:
You could shave a lot of weight if that barrel were six inches shorter.

Faxon 10.5 pencil is 14.5oz. Crazy light!!

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jdindadell · Mar 29, 2018

leadslinger972 said:
You could shave a lot of weight if that barrel were six inches shorter.

Very true. I am working on a pack/edc ar that used the patheon arms dolos and kentri products. Currently it has a 7.5" barrel with a pistol length gas system. I want to test it as is, but may go to a 10" barrel, and might as well go lightweight at the same time.

I have a faxon 14.5 midi that I patterned the barrel profile after. I also have a 10" lightweight rail for that barrel and an adjustable gas key. So I may build that upper and test it for accuracy against the current carbine length upper. If it is much better, I will cut the current barrel down and do a lightweight pistol build, possibly with the dolos removable barrel system.

rcm192 · Mar 29, 2018

DaSouthernYankee said:
Faxon 10.5 pencil is 14.5oz. Crazy light!!

Sent from my LG-H918 using Tapatalk

That is what I am using on my SBR. Pretty nice piece of work!

jdindadell · Apr 2, 2018

Got time to test this weekend, runs great with the SA adj gas block set 1.75 turns out.

Here is a lot of info. I plant to read it all.

https://www.ar15.com/forums/AR-15/Lightweight-Parts-List-with-WEIGHTS-AR-15-/118-638524/?page=79

Ultralight Ar15 build

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