Review: AIM Surplus Lightweight Nickel Boron AR-15 Bolt Carrier Group

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Aim Surplus (AIM) is a popular online retailer of gun accessories, firearms, and military & police surplus. What many may not know is that AIM is a huge seller of bolt carrier group (BCG) for AR style rifles. AIM’s customers had purchased over 50,000 of the AIM basic AR-15 BCG so far. The popularity is partly because of AIM BCG models are usually priced anywhere from 30-50% cheaper than what most AR-15 manufacturers are selling theirs.

 

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AIM is now offering a number of higher-end BCGs in addition to their basic model. Just released is the new AIM Lightweight BCG for AR-15. It comes in the Nickel Boron finish for $119.95 or in black Nitride for $109.95 with free shipping for both. The total weight is just 8.5 ounces or 28% lighter than the standard BCG.

 

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On my nickel boron sample, just about everything are nickel boron coated with the exception of the ejector, the firing pin and the firing pin retaining pin. There are many advantages of the nickel boron coating over the traditional phosphate finish for BCG, those including low fiction, self-lubricating, and more resistant to wear.

 

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I tested my AIM Nickel Boron Lightweight BCG sample in my 14.5-inch lightweight carbine during the recent Big 3 Media Event. Due to the reduction of the weight, AIM is recommending use their lightweight BCG in conjunction with an adjustable gas block. Of course, I didn’t do that. All I did was replaced the original BCG from the BCM upper with the AIM BCG. My AR-15 ran with it without any issue.

The image was taken after over 250-rounds of WPA (brass and steel cases), ZO1, HPR, and Fiocchi ammo were fired during the Big 3 Media Event and the destruction of the BMW car at the end. There’s hardly any carbon build-up on the AIM lightweight BCG as seen in the image. Also for the testing purpose, I didn’t put any lube on it. There were no stoppage of any kind even running it dry.

 

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Beside of the new lightweight BCG, AIM Surplus also offer the full size BCG-X model ($109.95) on the left with a mix of nickel boron and black nitride components. To the right of the AIM lightweight BCG is the AIM Evolution 3.0 reduce-fiction nitride BCG ($99.95). I will cover both of those AIM BCGs in another review.

 

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My testing AR-15 carbine leaning against the burned out BMW the day after on the Big 3 Media rifle range.

 

A short clip of me doing more testing after the Big 3 Media Event. From that, I would say AIM is right about suggesting using their lightweight BCG with an adjustable gas block, which would help reduce the recoil and making it a smoother shooting gun.

 



Writer and gear editor with articles published in major gun publications. A five year combat veteran of the US Marine Corps, Tim is also part of Point & Shoot Media Works, a producer of photography, video and web media for the firearms and shooting sport industry. Tim’s direct contact: Tyan.TFB -at- gmail.com


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  • pshinn

    I have a NiB coated BCG from Ares Armor out of Cali. Great component.

    I have a question for you well educated ‘operators’ and civilians alike.

    I understand weight is a concern, however what are the potential or well founded pitfalls to having this type of BCG in a build?

    ~pshinn
    CSD – Civilian Sheepdog

    • Eric S

      Pitfalls
      – Increased cyclic rate and the accompanying increased wear rate
      – Less overall mass to strip the next cartridge, feed it into the chamber, and lock the bolt

      Benefits
      – Using an adjustable gas system and lower recoil with less overall cycling mass
      – Can cure some problems with undergassed systems. 18″ barrels with rifle-length gas systems would be a good candidate. 16″ With carbine-length gas and non-adjustable block would be a bad choice.

    • The primary purpose of light weight carriers is for competition.

    • raz-0

      Depends on how you go about it. With just dumping a lightened carrier into a build, probably the biggest risk is being way too overgassed and outrunning the magazine spring. I’ve run into more people having issues outrunning the mag and getting a FTF than not having the energy to go fully into battery. Although Eric S is correct that that can also be an issue.

      With an adjustable gas block, probably the biggest issue is tuning it to be finicky and having it become undergassed in really cold weather, or just be unfriendly to ammo outside of the tuned sweet spot. My latest build/evolution of a build for my competition gun runs most anything in warmer weather. Cold weather testing is waiting for some cold to show up.

    • Sickshooter0

      I have the same BCG (Purchased to support Dimitri). I’m not aware of Ares ever making a low mass BCG so no worries. I have 5k+ rounds through 16″ and 18″ rifles and have never outrun the mag, FTF or FTE.

      • pshinn

        sickshooter0 I never mentioned that my NiB from Ares was low mass. Just that it was the only one I had. I appreciate all of the responses.

        I am actually going to put my NiB BCG into my new 300 AAC blkout and take my gunshow BCG.

        Should be a fun Christmas!

  • lol

    light weight carriers are a fad that needs to die. the goal in a true light weight build should be adjustable gas system with a full m16 carrier and carbine buffer. you want the mass close to the bolt head. when youve got a heavy buffer behind a light weight carrier, it’s just a$$ backwards.

    • raz-0

      I’m not saying you are wrong, but I’m curious as to your reasoning.

      I’ve done the full mass carrier with carbine (lightweight) buffer, full mass with rifle buffer, low mass with rifle buffer, low mass with lcarbine weight buffer, low mass with ultra light buffer. Adjustable gas, non adjustable, and I know what my results were, and they don’t agree with your ideal build (which I have shot, but haven’t built and lived with), and I’m not seeing how the distance of the mass from the bolt head makes a difference.

      • No you can say he is wrong.

        The light weight carriers aren’t aimed for the general market. They are aimed for the competition market, where not only do they use light weight carriers, but they often use even lighter weight buffers. That way you can really turn the gas down.

        • raz-0

          IMO, the issue runs into ergonomics as well. There is no truly right answer for ergonomics. Also not everyone’s goals are the same.

      • MR

        Coffeefreak has a Slowfire bolt thread on the Mac10 forum of Uzi Talk, where he describes that basic theory. Something about the miniscule amount of time it takes the energy from the cartridge firing to travel through the material of the bolt/carrier/etc. In that case, he was trying to slow it down as much as possible, so he placed the tungsten weight as far back on the bolt as he could(no carrier in MACs). I don’t know if the position of the weight actually made any difference in the rate of fire, or it was just the amount of weight, but the people that used those bolts seemed pretty happy with the ROF reduction.

        • raz-0

          Yeah mass will slow down cyclic rate. And where you place the mass can affect where the center of mass is, and given the AR platform operating off of a gas key or piston tab located at the top of the carrier means it may behave slightly differently, but in the case of a lightweight carrier/buffer combo, I can’t say that I have seen a lot complaints of carrier tilt or battering, but I also don’t see a lot of folks running it with lots of extra gas either.

          From my experience, if you want the softest shooting gun, you can go heavy and slow, or you can go lightened with reduced gas. In the lightened case, there’s usually a tipping point where you are too light and reducing gas to match means reliability issues, and not reducing gas means you get the carrier slammed home really hard and worst case carrier bounce to the point it causes issues in reliability. IMO even before the reliability threshold, you wind up introducing a dip to your sight picture which is just as bad, if not worse, then where you start in a mil-spec setup, just down instead of up.

          So like I said, I wont’ say he is wrong as info is missing on what he thinks is ideal, but I have a full mass, full gas, mid-length setup with an H1 carbine buffer in a carbine stock with a +10% spring, and it smacks the snot out of the buffer. It’s reliable, but it isn’t a soft shooting as a 16″ mid-length on a rifle length buffer setup, or and 18″ rifle length gas system with reduced gas and lightened bolt and carrier. His goals may be different than mine, so he may be “right” as far as his opinion goes.

          So far, absolute softest I have found is a carrier/bolt/buffer combo of about 12-13 oz. But barrel weight and comp figure into that, so it’s not absolute, even for a similar setup. In the end it’s a matter of ergonomics. IMO the primary goal for a lightened system is to maintain reasonable reliability while minimizing disruption of the sight picture. Some folks might care about running the ragged edge of decreasing split times by upping cyclic rate, but I’m not fast enough to have tos tart worrying about compromises made to increase that. I wind up waiting a hair on hoser sections with a heavy/heavy/full gas but reduced load setup, but not much.

          • bbies1973

            “given the AR platform operating off of a gas key or piston tab located at the top of the carrier means it may behave slightly differently”

            Piston, yes. However, a DI BCG does not operate off the gas key. The gas key is an extension of the gas tube, and it operates by directing gas *through* the key, into the space between the bolt and carrier, creating a line of force not just parallel to, but directly in line with the buffer and spring.

          • raz-0

            Except for that where tens of thousands of psi of gas makes that hard turn. The force shouldn’t matter, but I hedged my bets given we now have adjustable gas keys. Something I’m currently experimenting with in my most recent build.

  • dP

    Light weight carriers (combined with a l-w buffer like the JP LMOS) are useful for one thing only; competition. Lower reciprocating mass, combined with an adjustable gas block, minimizes the recoil impulse, which gets you back on target faster. It might save you a few hundreds of a second on your split times, but unless you shoot 3-gun or IPSC rifle matches at a pretty high level, your money is better spent otherwise.

    • J.K.

      Agreed on the low mass parts, but an adjustable gas block does have its value in reducing cyclic rate & pressure on overgassed and suppressed systems.

      • dP

        Absolutely. Although finely tuned gas systems do require more maintenance in order to function reliably, as long as you clean your BCG after every range trip, an adjustable gas block is a good upgrade for many AR configurations.

  • BoHeck

    So you tested and “reviewed” a low mass bcg without an adjustable gas system which is the one thing that allows you to take advantage of the reduction in mass…..I see no elements of a common review in this article. It’s just a description of the benefits of nickel boron, and some pictures of AIM’s other offerings along with some poses of your rifle.

    The review portion was that it worked after firing it a few times and seemed to wipe clean. Officially this might be the worst review I’ve ever seen.

    At the end you conclude that you should have taken AIM’s suggestion to use an adjustable gas block so that it might work as intended…Wow..you think?

    • Rock or Something

      It was almost as if the article wasn’t finished before being posted.

      • MR

        Also, link?

    • BillC

      I didn’t want to be the first to say all that.

      • BillC

        How’s the quality of the staking? Is the metal coated where the gas key covers the carrier? What’s the metal of the carrier and bolt? What springs or rings are used? Anything we should know about the extractor or ejector? What are some of the downsides of a lightened carrier? When should or shouldn’t this carrier be used? What’s it’s purpose?

        It was just a whizbang, wowwee, it kinda worked on my rifle with a couple hundred rounds “review”.

        • handbanana

          Quality of the staking is fine. Of course, since my keys are staked, I don’t know if there’s finishing underneath the key. It seems as though there is, however. 9310 steel for the bolt, 8620 steel for the carrier and key. Sorry, no idea about the gas rings haha. Extractor is shot-peened 4140 steel. The BCGs are MPI tested, so theoretically that should mean you don’t get one with micro fractures and flaws that will eventually cause failure. The reality is that MPI testing is largely marketing speak, the real distinction is what their rejection/acceptance criteria is. Milspec is, according to Andrew Tuohy, about 30-40% rejection if I remember correctly, which is not acceptable for the majority of profit-driven enterprises. Rather, civilian companies generally have lower rejection rates and opt instead to just replace the few failed carriers sent to customers down the road (if at all). Still, you can know that there’s SOME criteria for these MPI tested BCGs. If you want me to remark on the overall quality, I would say it’s great for $110, but there are visible tool marks all over the carrier, so it’s also definitely not a high-end BCG.

          Downsides of the lightened carrier is a reduction of reliability, mainly pertinent to those shooting different types of ammunition. With less mass, the carrier will have less force to feed rounds as the action spring brings it forward, so there’s a greater chance of a failure-to-feed. This is why everyone is saying you need an adjustable gas system–you tune the gun to just barely have enough gas to cycle the action. If you switch ammo you may end up needing to readjust. On the upside, a carrier with less mass and operating force means less recoil, but really only in the sense that the gun’s action will cycle softer. I really can’t say objectively if the reduced reliability is much of a detriment, but obviously a military doesn’t want to deal with adjustable gas blocks. Do I notice a difference in recoil? Sadly, no. A good muzzle brake does more in my experience, but the main market for lightweight bolt carriers is generally the competition community, whose priority is to run the gun as fast as possible with match ammo that they specifically select (or load).

          • BillC

            I have the regular AIM Nitride BCG. Got it in a trade of parts I had for parts I needed. I like it in the sense that I use it in a 300 Black range toy and it has worked for few hundred rounds I’ve shot through it, mostly suppressed. It’s easier to clean that my milspec Premium PSA BCG that I used my my 5.56mm SBR. Other that that, I don’t know anything about it.

            See I can do a review too. Now where can I upload some pictures?

    • raz-0

      Well technically, if you buy a barrel with an undersized gas port, you don’t necessarily need an adjustable gas block.

      I built one with adjustable gas, my friend went with a low mass carrier after building up on a nordic components barrel which has a port on the small side of reliable. They both shoot pretty similarly.

    • handbanana

      Unfortunately the gun dick-measuring race is pretty competitive haha, so it’s not rare to see writers for general gun blogs to not be as knowledgeable on the AR platform as many of us particular enthusiasts (for the platform). I mean these have been out for a while–I’ve purchased the lightweight NiB, returned it, and purchased the Nitride, which is in my main carbine right now. I even have their standard in nitride (the point is not that I have things, but that these have been out a while). These guys are obviously a bit behind if they think AIM BCG’s are news, but that’s just the standard rate of publishing. It also obviously takes some time to test and review, but I understand the contention is that this is not a very adequate review. I find that lots of specific products have very few reviews early enough for us AR guys, especially since this is a pretty individualistic culture. Anyways, I of course do have an adjustable gas system so I will respond to other posters asking questions about the BCG.

  • Mrninjatoes

    Don’t put anything low mass on a fighting rifle. Where are the metal specs? Is the bolt carrier 8620? 9310? What is the bolt made of? 8620? 9310? 158 Carpenter? AEMET? Was there a black spring extractor spring? Crane O-ring? This review is little lite on technical specs. Nice pictures though.

    • iksnilol

      I think the low mass carrier gives an advantage. More gas will increase its velocity more than similar amount of gas in a heavier carrier. Should last longer (if used with an adjustable gas block) and should be able to work in more adverse conditions.

  • handbanana

    Unfortunately the gun dick-measuring race is pretty competitive haha, so it’s not rare to see writers for general gun blogs to not be as knowledgeable on the AR platform as many of us particular enthusiasts (for the platform). Ha I mean these have been out for a while–I’ve purchased the lightweight NiB, returned it, and purchased the Nitride, which is in my main carbine right now. I even have their standard in nitride (the point is not that I have things, but that these have been out a while). These guys are obviously a bit behind if they think AIM BCG’s are news, but that’s just the standard rate of publishing. It also obviously takes some time to test and review, but I understand the contention is that this is not a very adequate review. I find that lots of specific products have very few reviews early enough for us AR guys, especially since this is a pretty individualistic culture. Anyways, I of course do have an adjustable gas system so I will respond to other posters asking questions about the BCG.

  • TJbrena

    “There are many advantages of the nickel boron coating over the traditional phosphate finish for BCG, those including low fiction, self-lubricating, and more resistant to wear.”

    “fiction?” Are your BCGs are big on creative writing and storytelling? Now I want guns that can read to me.

    • Dan

      “Are your BCGs are big on creative” do you need the second are? Or were you too busy trying to get your jabs in at the writer?

  • handbanana

    Higher priced as in BCGs under $200, yes. I would have a hard time seriously considering a phosphated carrier from a name brand for $50-100 more. I think this is likely one of the best deals around for anything considered standard build. Once you get into the really nice BCGs, like a Sharps or something, I think the quality will definitely be much higher, with no visible tool marks and likely greater testing rejection rates. High diminishing returns, though, as they will pretty much all function rather similarly.

  • JK

    Looks like a semi-auto bolt carrier. Not that it’d really make a difference to me at this point, but who knows, I might pick up a RDIAS at some point and want to make a high RPM “buzz gun” for one of my options.

  • Jwedel1231

    Does anyone make a “high-mass” bolt carrier?

  • Michael Valera

    Can we stop using the phrase “self lubricating”? I think we all know by now that claim is BS.

  • bbies1973

    We’re all talking about lightweight vs. full mass, and debating steel types and coatings. However, the single greatest improvement of the DI BCG is machining in a gas key as part of the carrier. Every time a fancy carrier is discussed, people always ask about staking of the gas key. Why continue to incorporate 3 more unnecessary parts (key + 2 screws) and increase the chance of failure at all?

    Certainly, at the time of Stoner’s design, bolting on a gas key may have been the more efficient method of manufacture, especially when the cost becomes a consideration for a government contract. However, manufacturers today aren’t using grandpa’s mill to make these parts, and the overhead costs of employee labor aren’t what they were during Stoner’s time. Not only do modern machining capabilities and labor costs make it more efficient to produce a carrier with an integrated gas key, but machining two separate parts and screwing/staking them together increases the failure potential by using 4 parts to do what a single piece can do.

    It just doesn’t make sense in the 21st Century.