Best Lightweight Bolt Carrier Groups (BCG) [2018]

Looking to really reduce your AR double-tap times?

You’ll want to go the lightweight low-mass bolt carrier group (BCG) route.

Bunch of BCG's
Bunch of BCG’s

The BCG is the piece of metal moving back and forth between each shot.  Lower the weight…and you’ll lower the disturbance to your rifle and sight picture.

We’ll cover the most popular ones out right now, other upgrades you should do at the same time, and reliability concerns.

Sneek peak, here are our top picks for lightweight BCGs:

Table of Contents

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Why Get a Lightweight BCG?

As we mentioned above…lowering the mass of the primary thing moving around in your rifle is going to help minimize the overall movement.

This will let you get back on target faster and reduce the felt recoil.

AR-15 BCG Function
AR-15 BCG Function, 45Snipers

The normal advice is to use the full-auto (FA) BCG compared to the lighter semi-auto BCG when used in rifles where reliability is key.

And don’t worry…full-auto BCG’s are perfectly legal.  It’s the trigger group that makes something actually full-auto.

The extra mass of FA BCG’s keeps things running smoothly in over-gassed AR-15’s that were made to run a variety of ammo and in crappy environments.

FA vs Semi BCG
FA vs Semi BCG (Left = Semi, Right = Full-Auto), TTAG

Since you’re looking at lightweight BCG’s…you’re probably messing around with a secondary AR-15…likely for competition.

You probably won’t be scrounging for ammo on the battlefield so you can lower the amount of mass needed to make your rifle still run 100%.

I know what you’re thinking…

What about using the lighter semi-auto BCG?

It’s only slightly less weight at 10 oz and change compared to the FA of 11.5 oz…while the ones we’re going to talk about are getting down to the 5 oz range.

How Do You Lower the Mass of BCG’s?

First…you can cut away “unnecessary” parts of the steel carrier.

And second…you can use more exotic materials that weigh less.

You’ll see a mixture of these two types of mass lowering techniques in our roundup.

Speaking of which…let’s get started!

Best Lightweight BCGs

We’ve tried out three of the most popular ones on the market…

Lightweight BCG's
Lightweight BCG’s (Top to Bottom, Rubber City Armory, JP LMOS, Faxon)

1. JP Enterprises Low Mass (LMOS) BCG

JP Enterprises Low Mass (LMOS) BCG

JP Enterprises Low Mass (LMOS) BCG

  • Weight: 8.9 oz
  • Price: $335
  • Material: Steel
  • Notes: No serrations for use of the forward assist

JP was one of, if not the first, major company to sell lightweight BCGs.  For a while, they stopped, but now they are back at it again with their Low Mass Operating System (LMOS) models.

We’re at around the 1000 round count and don’t see any major wearing…just sweet low recoil shooting.  It’s made of steel so it should keep on chugging.

Just keep in mind that you’ll lose the use of your forward assist function (who has ever actually used their forward assist though?).

*EDIT* I originally stated that this model was aluminum.

2. JP Enterprises Ultra Low Mass BCG

Lightest
JP Enterprises Ultra Low Mass BCG

JP Enterprises Ultra Low Mass BCG

  • Weight: 5.8 oz
  • Price: $437
  • Material: Aluminum
  • Notes: Lightest BCG on the market today

This new BCG from JP recently came out so we haven’t gotten our mitts on it yet…but we had to include it since it truly is ULTRA low mass.

But with great weight reduction comes great cost.

Both monetarily and reduced life.  Because the BCG is the same material as your upper receiver (aluminum)…it will see some wear and degradation as it does its job…to a point where you have to get a new one.  For that reason, JP recommends that you use the Ultra only in competition rifles.

It now has forward assist capabilities, but after a couple thousand rounds you’ll have to junk it for a new one.

3. Faxon Lightweight BCG

Most Affordable
Faxon Lightweight BCG

Faxon Lightweight BCG

  • Weight: 8.5 oz
  • Price: $249
  • Material: Steel

From Faxon, maker of affordable and great barrels comes their lightweight steel BCG.  Check out all of those weight reducing cuts!

Since it’s steel…the carrier should last almost indefinitely like its semi and full-auto brethren.

We’ve been running it in our overall super lightweight build for around 800 rounds and it’s been running smooth as butter.

Lightweight Upper Build, Faxon and Brigand Arms
Lightweight Upper Build, Faxon and Brigand Arms

The price is right too at about $200 less than the normal JP aluminum BCG and even less weight.  Just good luck finding it in stock!

4. JP Enterprises LMOS Steel Carrier

JP Enterprises LMOS Steel Carrier

JP Enterprises LMOS Steel Carrier

  • Weight: 8.8 oz (with bolt)
  • Price: $215
  • Material: Steel
  • Notes: Carrier only…you’ll need a bolt from somewhere else, plus no forward assist serrations

Since at the time of publication the Faxon was sold out everywhere…I’m throwing in JP’s steel version for price-conscious lightweight aficionados.

The weight is on par and you’ll save if you scrounge up a bolt from a previous BCG.

5. Rubber City Armory (RCA) Titanium BCG

Thank you, titanium, for bringing the best of both worlds…the lightness of aluminum but the durability of steel.

Lightweight BCG's
RCA Titanium BCG (Top)
  • Weight: 7.8 oz (with bolt)
  • Price: $360
  • Material: Titanium

You’ll shave off 32% of the weight compared to a standard BCG, but you won’t run into the wear problems of aluminum carriers.

Editor's Choice
Rubber City Armory Titanium BCG

Rubber City Armory Titanium BCG

Prices accurate at time of writing

I’ve been running the RCA for over a year (estimate 2500 rounds) in my competition build and I’m still not tired of tapers showing me the touching double-taps I get on targets.

Readers' Ratings

5/5 (176)

Your Rating?

6. Brownells Lightweight BCG

A newcomer from Brownells which usually has great self-branded stuff.  When you want to try out going lightweight without breaking the bank.

Comes in three flavors of Nitride, Nickel Boron (my recommendation), or TiN (gold…yea you know who you are).

Brownells Lightweight BCG

Brownells Lightweight BCG

Prices accurate at time of writing

What Other Mods?

Since the AR-15 is a well-oiled machine where multiple parts have to work together…you can’t just change up 30% of one thing without having to mod others.

Here’s what I found to have the best reliability combined with a lighter BCG.

JP Captured Spring

Best Buffer System
JP Captured Spring

JP Captured Spring

Gets rid of the *sproing* of the regular buffer tube spring…and makes your AR-15 feel and shoot SO much better.  Especially needed since the standard buffer and spring are too heavy/stiff for your lightweight BCG.

Opt for the spring kit if you decide to go this route.  I originally got the single pack and needed the lightest spring to go with my RCA BCG.

The kit lets you customize things to just how you like them.

Not ready to make the jump to the entire system…check out a lighter buffer ($57) and tuned spring ($19).

Superlative Adjustable Gas Block

Best Adjustable Gas Block
Superlative Arms Adjustable Gas Block

Superlative Arms Adjustable Gas Block

You’ll really want an adjustable gas block since you’ll need less gas to move the lighter BCG.  Otherwise, you’ll have a really fast moving BCG which might actually increase felt recoil and damage parts.

My pick is for the Superlative Arms gas block (full review) since it has the bleed off hole technology.

Conclusion

Lightweight and Regular BCG's
Lightweight and Regular BCG’s

So there you have it…our list of the best lightweight BCG’s on the market right now.

Want more awesome AR-15 reviews and guides? Take a look at this!

If you have any questions about swapping your bolt carrier group out, how to choose a new one, or you just want to tell others how much better (or worse) you’re shooting with a low-mass BCG, be sure to let us know in the comments below!

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Dan
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Dan

Eric, thank you for taking the time to share what you’ve learned. I am starting my first AR15 build, my first rifle in 25 years, and I’ve taken this info to heart.
Thanks again for your time.
Pew pew baby.
DQ

Ed Gallardo
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Ed Gallardo

You should do a review on the Brownells reduced weight BCGs! All three flavors; and please cover reliability, wear, coating retention (for NiB and TiN), lubricity, rust endurance for the nitride version, and opinion/review on “how it feels”, as well as how to best combine it with other parts to fully benefit from this BCG (buffer system, gas blocks, etc). If you can pull this off it would be great, thanks!

Links of other reviews on this also welcomed…Thanks again!

robert a lasley
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robert a lasley

You say the price is 200 less than the jp aluminium on the faxon and it weighs less. The 1st part of that is correct the second is not i don’t think. For the jp aluminum you say 5. something and the faxon 8. something.

inski21
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inski21

In conjunction with the adjustable gas block, can a reduced buffer weight do the same thing as a reduced BCG? Essentially they are never separated. I’m just planning my steps for my competition 3G rifle.

Matty_Guns
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Matty_Guns

buffer absorbs the bcg.. no not the same thing.. the mass of the bcg is felt recoil. the weight of buffer absorbs energy of kinetic mass.(bcg) .. very different things.

Jason
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Jason

well I am a little late to reading the part about not building a light weight AR as my first build.
So far I have the Balios Lite Gen @ receiver set. Daniel Defense 5.56 16′ light weight barrel.
Any suggestions on where I should go with this?
Can I Use the Balios lite for a regular weight set up. then change parts out as I get more familiar with it. Only thing I know about Ar’s is what I have read in the last 2 days.
Thank you for any help.