5 Best Lightweight Bolt Carrier Groups (BCG) [2019 Hands-On]

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

  • 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.

JP Ultralight BCGs
JP Ultralight BCGs

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 BCG
437
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

  • 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 Light BCG
249
at Faxon Firearms

Prices accurate at time of writing

Prices accurate at time of writing

  • 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

  • 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.

Best Light BCG
360
at Brownells

Prices accurate at time of writing

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 (399)

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).

119
at Brownells

Prices accurate at time of writing

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
162
at Rainier Arms

Prices accurate at time of writing

Prices accurate at time of writing

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
89
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

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!

27 Leave a Reply

  • Bob H- Arizona

    Eric Looking for a left handed BCG group, light weight, NIb -556 and 6.5 grendel II fallowed your page on light weight BCG's not alot out there in LH catagory. Young manufacturing has one that is chrome, but weight is at 10. Bolts, I can buy if need be, its just the carrier . Iron City Rifle works has a great looking line of RH BCGs but online page shows NO LH . need to call and ask if they can manufacture. same with Young. What our opion on ajustable gas keys vs ajustable blocks? Question " Do you know of any compainies that I may have missed? Or is this a NO NO to ask that question due to "promoting". Thanks

    5 months ago
  • JEREMY J FABRIZIO

    FYI, the Brownells low mass BCG WILL NOT run in a milspec tube. I ordered one for a custom pistol build and i could not pull back the charging handle. I tried in my rifle and it would cycle manually but with a lot of resistance and would be afraid to fire it. Brownells tech said it is intended for competition guns using commercial tubes. From ordering, to getting a refund after it was returned, it took almost 2 months! Not one person told me the same thing the entire wait. I even had to have my bank file a dispute.

    7 months ago
    • Lee

      I have the Brownells Lightweight BCG and a milspec tube with a reduced power spring and it works just fine.

      3 weeks ago
  • Jake

    Being in Canada we have a lot of what you call SBRs, I am having issues with a 10in in 223. I admit I am using bargain NEA barrel, and BCG. I get double feeds and short stroking, stove piping, changed rings and drilled out gas port with some.. 50% improvement but still feel at a loss. Another gent with a 7,5in said he switched to a semi BCG and bingo, would a lighter BCG and better quality bolt with stronger springs help?

    10 months ago
    • Josh

      That's a hard question to answer without taking all parts of your specific gun into account. The type of gas port hole in your barrel, gas port, buffer weight and spring, and BCG all play a factor in how your gun will run. If you don't have an adjustable gas block i'd start there. What you will want to do is close the port all the way and back it out a bit. Then shoot one shot and continue to use more gas till the gun cycles. Once the gun cycles i'd put like 10 rounds through it to make sure everything is good. There are videos on how to work on the gas system of an AR on youtube, if you need more info i would start there.

      9 months ago
      • Jake

        Thanks for the reply. I like the idea with the gas Port. I will switch to a 11.5 in barrel or longer to eliminate short dwell time, i have had some success since we talked, switched to Winchester white box (much better) and coated gas rings in heavier oil.. oh gas rings gaps we're all aligned.... Ahhhh. Also coated BCG and upper in Teflon. That being said i am using bargain parts.

        9 months ago
  • 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

    1 year ago
  • 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!

    1 year ago
    • Eric Hung

      Yup, when we update the article we will get our hands on a few!

      1 year ago
  • 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.

    1 year ago
  • 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.

    1 year ago
    • 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.

      1 year ago
    • Eric Hung

      I've seen them combined (JP has one) but not sure if it will achieve the same thing by itself.

      1 year ago
  • 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.

    1 year ago
    • Eric Hung

      The Balios should be good to go for whatever weight set up you're looking for. We have tons of AR info in our AR-15 section.

      1 year ago
      • Jason

        Thank you very much for the reply

        1 year ago
  • Bryan259

    why aren't any of the Bolts or Cam pins Titanium? I have a whiskey arms Carrier (109 grams) v seven ti firing pin ( 4.5 grams) Nickel Boron Cam pin (7.5 grams) and a nickel Boron Bolt (43.57 grams) total weight 166 grams or 5.85 oz would like to get it even lower for fun. Looking for the lightest most durable Bolt and cam pin to swap out. Not having any luck on finding weights on them or manufacturers of Titanium and i cant seem to find why. Also not opposed to a lighter retaining clip but that is silly.

    1 year ago
    • Eric Hung

      I'm not too sure why, but that is a light setup you've got there!

      1 year ago
  • Dwight Looi

    Eric, you failed to mention the real reason aluminum BCGs wear like crazy. It is NOT because aluminum is softer. It is because Aluminum-on-Aluminum friction is murderously high. That is why in engineering making aluminum parts rub on aluminum parts is a no-no. The friction co-efficient between steel and steel is about 0.5 to 0.8. Between aluminum and steel is about 0.6. Between steel and bronze (commonly used in bearings) is about 0.2. Steel-Teflon is about 0.1. Aluminum-aluminum friction co-efficient is about 1.3 -- the highest of any commonly known and used material! It's murder!!! That is why aluminum engine blocks use iron cylinder liners or a plasma coating of iron or some other material, so as to avoid making those aluminum pistons rub on aluminum cylinder walls. That is also why you should NEVER use an aluminum BCG on an aluminum receiver!

    1 year ago
    • Eric Hung

      Thanks for the knowledge bombs, Dwight!

      1 year ago
  • rob

    Anyone have experience with, or an educated opinion about, the 2A Armament Lightweight "Adjustable" ("Regulated") 5.56/300 BCG? At least theoretically, on its own it is supposed to provide both the benefits of an adjustable gas block and lightweight BCG. THANKS

    1 year ago
  • Jason

    Thanks for the info, wish you could have included the Aim Surplus and Anderson Manufacturing lightweight BCG options.

    2 years ago
  • Mattb

    I enjoy this write up, but it seems limited to competition guns. Moreover, doesn't it make sense that if you wanted fast follow up shots that more mass + tuning the gas and buffer would result in the fastest BCG reset? I can understand this set up for 3-gun racing though where recoil + follow-up would be the idea.

    2 years ago
    • Eric Hung

      Yup, it's pretty much limited to competition guns. Your scenario might result in faster reset but like you said...the recoil/follow-up might be affected.

      2 years ago
  • Mike KLEIN

    Excellent article on low mass bcg's as with all your articles,very informative

    2 years ago
  • Ben

    I wouldnt go this route for a first build but once you are familiar with how everything on your AR works go for it and like the article says you will need to change buffer tube springs and get an adjustable gas block.

    2 years ago
    • Eric Hung

      Yup...I'd wait until maybe the third!

      2 years ago
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