Lightweight AR Builders Club

[Squid556]

Here is a lightweight build I did recently. Haven’t tested it yet. 5 pounds 8 ounces.
View attachment 243402 View attachment 243403
INGO Lower Receiver $90
Faxon 16” Gunner Barrel $166.25
Faxon Lightweight BCG $248.99
Aero Precision Upper $94.99
VG6 Titanium Epsilon Brake(clone)$80.00
Noveske QD End Plate $23.76
DPMS Castle Nut $3.99
Magpul MOE+ Grip $22.75
VLTOR Buffer Tube $37.99
M.I. 3GML Handguard $159.95
Magpul MOE Trigger Guard $8.50
Wilson Combat Gas Tube $18.29
Geissele Super 42 Buffer/Spring $65.00
Radian Talon Safety $47.45
Radian Raptor Charging Handle $75.95
LANTAC Titanium Takedown Pins $35.99
Titanium Mag Release $25.00
Seekins Mag Release Button $5.69
Seekins Bolt Catch $12.34
Sig Sauer ROMEO5X/XDR $249.99
V7 Titanium Mag Release $39.50

I’m very curious to know how reliable the Gunner bolt carrier group is.

 

[Squid556]

Does anyone have experiences with what works and what doesn’t work with lightweight bolt carrier groups?

 

[abraham743]

Here is my lightweight build, it comes in at 5.25 lbs.

• 80% aluminum lower
• Spikes tactical adjustable trigger
• MFT Minimalist buttstock
• Slick side upper
• Fail Zero NiB bolt carrier group
• BCM KMR A10 hand guard
• Faxon 14” pencil barrel with pinned and welded brake

I don’t think I need it any lighter and it shoots great too!

 

[BoilerWes]

I did a light SBR build. 2a upper and lower with Proof 10.5 Barrel. Vseven Helios comp. Handles and shoots great.

 

[DDadams]

Does anyone have experiences with what works and what doesn’t work with lightweight bolt carrier groups?

Anything 8 ounces + doesn't have much difficulty. The ones like 2A Armaments ultralight adjustable BCG (6oz) can be difficult

 

[Gabriel]

Here is my lightweight build, it comes in at 5.25 lbs.

• 80% aluminum lower
• Spikes tactical adjustable trigger
• MFT Minimalist buttstock
• Slick side upper
• Fail Zero NiB bolt carrier group
• BCM KMR A10 hand guard
• Faxon 14” pencil barrel with pinned and welded brake

I don’t think I need it any lighter and it shoots great too!

How do you know how it shoots without sights on it?

 

[abraham743]

I had a Holosun on it. I have been making some changes, I just put an sig Romeo 5 on it just because it is smaller and lighter. I weighed between sights

 

[Max Volume]

I built a 350L upper for bambi without thinking about weight but it will carry nicely. Kitchen scale says 5 lbs 10.75 ounces. Used an Aero Precision M4E standard receiver, CMMG 16.1 inch barrel with a thread protector and Midwest Industries 10.5 inch handguard. It is on an old Bushmaster lower with the Bushmaster BCG and charging handle. Awaiting a Vortex scope.

 

[Squid556]

Doing a deep dive tonight on a cost per weight loss analysis. Some conclusions I've come to...

In my current situation as shown in the OP.... By changing red dot, upper, carrier, and lower receiver I can drop 10 oz of weight for $380. I feel that's a fair price to pay to drop over a half pound and get another lower out of the deal.

Now here's where the point of diminishing returns shows up. If I buy dedicated lightweight pins, safety, grip bolt, castle nut and plate I can drop another 1.5 oz for $170. Personally I don't feel like that's a worthwhile path to go. Those titanium parts to fill the lower can shed some weight but I'm just not seeing the value there like I did in the paragraph above.

I think the diminishing returns game is going to vary from shooter to shooter. Being somewhat of a practical man I'm not going to let myself go all the way down the titanium rabbit hole.

 

[Squid556]

I had no idea the hours of research I'd have in this project. There are so many products on the market now! The spreadsheet resource I shared in the first couple posts has been a huge help and so far I've found it to be fairly accurate.

Hoping others can learn something from the things discussed here. Might just save you a bunch time and money.

 

[djay7677]

Does anyone have experiences with what works and what doesn’t work with lightweight bolt carrier groups?

FosTecH Complete LOW MASS Bolt Carrier Group (Nickel Boron) – Fostech, Inc.

fostech.com

Have run this Lightweight Fostech with a binary trigger. Zero issues.

 

[Squid556]

FosTecH Complete LOW MASS Bolt Carrier Group (Nickel Boron) – Fostech, Inc.

fostech.com

Have run this Lightweight Fostech with a binary trigger. Zero issues.

What is your barrel / gas system length / buffer weight?

 

[djay7677]

What is your barrel / gas system length / buffer weight?

14.5" barrel with 2" brake pinned/welded. Daniel Defense mid-length gas tube. Geissele H2 Spring Buffer combo.

 

[buttonblue]

Might be time to lose the forward assist. Maybe an upper with no FA accommodation?

 

[Squid556]

Might be time to lose the forward assist. Maybe an upper with no FA accommodation?

The timing of this comment is surreal. Tonight I disassembled two of my uppers and ended up with both types of receiver. By my scale you can drop another 1.2 oz just by going non FA




As well as using a non FA upper for the rebuild I’m going to switch to a polymer dust cover. Should be able to drop nearly another half oz by going with the polymer door

Ultimate Dust Cover for .223/5.56

The SI UDC enables users to attach and detach the cover in 5 to 10 seconds with ease (stock dust cover will take more time to remove)! It is constructed of a high-density polymer making it more durable and functional than the traditional dust covers. The Ultimate Dust Cover features an...

www.strikeindustries.com

 

[JEBland]

Might be time to lose the forward assist. Maybe an upper with no FA accommodation?

I keep looking at the KE Arms and the FCD for the scallops on the tang above the charging handle in case I decide to get BUIS... But I just don't need to drop $100-200 ea. on upper receivers right now. I'm also not an internet operator, so maybe someone with more experience can weigh in on the merits of brand X over brand Y.

 

[Squid556]

So it begins…

2A Armament Palouse Lite lower. 2 oz weight savings over mil spec. This is still 7075 T6. Couldn’t justify the extra cost to go lighter materials. Got a “blemished” lower for $120

Palouse-Lite Forged Lower Receiver

2A Armament is the original lightweight AR manufacturer. High Quality, lightweight AR-15, AR22LR, and AR-10 rifles.

www.2a-arms.com

 

[Squid556]

Put together the 2A Palouse lower tonight and overall quite impressed with the product. Machine work is great, all the dimensions mated with their parts nicely. Even includes a threaded plug that lets you take the slop out of the upper/lower when mated. They have removed a lot of material while leaving enough in there.

That being said though... While torquing the castle nut, I cautiously watched the receiver flex. So I took it off the mag block fixture and instead grabbed the vice along the buffer tube underbelly. Much sturdier, got the job done.

 

[Squid556]

A quick and easy way to drop a little weight, oddly enough is in the dust cover. Standard assembled door is about 3/4 oz.

I’ve found the Magpul polymer door to be only 1/4 oz. They only cost about 15 dollars and it’s an easy half oz.

What turned me onto the idea first was seeing a Daniel Defense rifle at my LGS and it was factory equipped with a polymer dust cover. So far so good. Glad I went this route.

 

[Squid556]

Big weight savings to be had in optics choice. The SPARC is good and seems more robust than the Holosun. That being said the Holosun has been out long enough to prove itself and I think it’s up to the task. Added benefit of the change is having a motion activated red dot now.


Nearly 4 oz weight savings to be had here, cutting optic weight by 50%. So far I’m quite happy with this decision.