Archangel14
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Does anyone have an opinion as to the quality of AIM Surplus BCG's? Looking for first hand experience. Thanks!
AIM Surplus BCG
- Thread starter Archangel14
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Archangel14
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- Mar 16, 2012
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I see that they sell BCG's made from different types of metal (8620, 9310). I'm aware that 158 carpenter's steel is "mil-spec", but I'm wondering how these other steels, and various coatings, hold up. 
NWcityguy2
Member
While 9310 Bolts are new-ish to the market, the examples that exist demonstrate that they are on par with 158 Carpenter. 8620 is what most of the low end bolts are made of. Think DPMS/Bushmaster/Anyone who doesn't advertise what their bolt is made of. They are prone to breaking after a few thousand rounds. 8620 is also the material used for carriers, and it works well for that.
I have an M-16 mpi tested bcg I got from Surplus Ammo for 90 bucks. It's been solid, no hiccups or issues so far. No where near the rounds through it compared to my Colt or Model One build yet, but the price made it attractive. They list all the tech specs:
http://www.surplusammo.com/saa-m16-complete-bolt-carrier-group-mpi-tested-223-5-56/
http://www.surplusammo.com/saa-m16-complete-bolt-carrier-group-mpi-tested-223-5-56/
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BCG = Bolt Carrier Group. That's the part with the staked gas key. The bolt might be included but when the steel alloy is mentioned it's mostly the bolt itself that gets discussed. The carrier alloy is rarely mentioned, and the MPI testing is done to the bolt only.
That's the fun part about figuring out the offers - you have to vet the bolt alone for it's specs, then you get to add on the bolt carrier for it's specific features - like, having good staking on the key.
Not to forget that even milspec or better bolts can still have issues after 5,000 rounds, and that the average AR shooter takes a long time to get thru that much ammo. A totally milspec bolt - or better - can still develop cracks or shear a lug under use. That is why the military requires close inspection. Just pegging it to a round count won't do, and throwing away a bolt with no defects isn't good preventative maintenance.
In the big picture a user could pick a bolt that wasn't top tier alloy and get good service from it, because that rifle had optimum timing with cycling speeds within specs that didn't batter it. The next gun could be a bolt eater because nothing is within the optimum windows of operation - the best superbolt out there could get chewed up all too soon. Think M16 with 20" barrel shooting nice handloads vs AR pistol with full house NATO. Or, vice versa. Hard to say.
We just do the best we can. Inspect carefully when cleaning, you never know when the cracks will develop. All MPI and a good alloy will do for the bolt is prevent them showing up early - they don't guarantee you won't ever see any. Bolts should be considered durable but expendable, like magazines and barrels. They can and will wear out.
That's the fun part about figuring out the offers - you have to vet the bolt alone for it's specs, then you get to add on the bolt carrier for it's specific features - like, having good staking on the key.
Not to forget that even milspec or better bolts can still have issues after 5,000 rounds, and that the average AR shooter takes a long time to get thru that much ammo. A totally milspec bolt - or better - can still develop cracks or shear a lug under use. That is why the military requires close inspection. Just pegging it to a round count won't do, and throwing away a bolt with no defects isn't good preventative maintenance.
In the big picture a user could pick a bolt that wasn't top tier alloy and get good service from it, because that rifle had optimum timing with cycling speeds within specs that didn't batter it. The next gun could be a bolt eater because nothing is within the optimum windows of operation - the best superbolt out there could get chewed up all too soon. Think M16 with 20" barrel shooting nice handloads vs AR pistol with full house NATO. Or, vice versa. Hard to say.
We just do the best we can. Inspect carefully when cleaning, you never know when the cracks will develop. All MPI and a good alloy will do for the bolt is prevent them showing up early - they don't guarantee you won't ever see any. Bolts should be considered durable but expendable, like magazines and barrels. They can and will wear out.
Group indicates the complete carrier, bolt, firing pin, cam pin, and fp retaining pin.
Regarding the metal used, AIM does a good job of breaking down each piece in their description. 8620 for carrier, 9310 for bolt, etc.. even the cam pin and extractor. I like nitrided parts too. I have one of these in a 5.56 build and it seems to do the job. They offer 6.8 SPC and x39 versions too.
http://www.aimsurplus.com/catalog.aspx?groupid=723&name=Bolts+&+Bolt+Carrier+Groups
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Jackal
Member
He likes them: https://www.youtube.com/watch?v=C7JB1MnyK2g
I use AIM's c158 mpi/hpt bolt in my Adams Arms carrier, so far so good. As for c158 vs 9310, a well made 9310 with proper heat treat is going to be just as good or better than c158. The military contractors only settled on c158 because it was easier to heat treat, thereby increasing production/lowering costs... I have owned almost every bolt type/composition and so far, whether a cheap DPMS/Bushmaster bolt or a Colt bcg, I've had no failures with any of them.
I use AIM's c158 mpi/hpt bolt in my Adams Arms carrier, so far so good. As for c158 vs 9310, a well made 9310 with proper heat treat is going to be just as good or better than c158. The military contractors only settled on c158 because it was easier to heat treat, thereby increasing production/lowering costs... I have owned almost every bolt type/composition and so far, whether a cheap DPMS/Bushmaster bolt or a Colt bcg, I've had no failures with any of them.
moxie
Member
I bought one of their generic milspec M16 BCGs a while back. Very nicely put together. I got it as a backup so just ran a few hundred rounds through it before storing it away. But it ran flawlessly and looked like new. Based on that one experience I can say I'd buy another from AIM.
BCG=
Carrier assy. which includes gas key
Bolt assy. which includes extractor and gas rings. Extractor may have an O-ring.
Firing pin including retaining pin (cotter key)
Cam pin
In other words, the whole group.
AIM usually does specify the alloy for the carrier itself, usually 8620 steel, chrome lined. They are very upfront about their stuff.
BCG=
Carrier assy. which includes gas key
Bolt assy. which includes extractor and gas rings. Extractor may have an O-ring.
Firing pin including retaining pin (cotter key)
Cam pin
In other words, the whole group.
AIM usually does specify the alloy for the carrier itself, usually 8620 steel, chrome lined. They are very upfront about their stuff.
I have one in 10.5" AR pistol. Never had a problem with it - 100% reliability so far in a little over 500 rounds. 9310 bolt with 8620 chrome-lined carrier. Staking looks good & has extractor insert. The bolt head does not appear to be shot-peened, but, as I said, it still has always worked great.
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MIL-DOT
member
AIM has a very solid reputation among their customers (including me). I've read other reports on these BCG's, in places like AR15.com, and the reports I've heard, as best I can recall, have all been very positive.
I've owned a few of them. They are good to go. I just got one of their v2 nitride ones in the mail the other day with the c158 bolt. They are made properly and work well...the staking on this one isn't amazing but it's good enough to where I wouldn't worry about it. I used to buy all these $200 bcgs...but a few of the $100 ones in the last year or so seem almost as good as the $200 ones from a few years ago. Look at companies like Toolcraft for instance.
MachIVshooter
Member
AIM BCGs are good to go in my experience.
This. 9310 is actually slightly superior to Carpenter 158 alloy, but has a narrower temperature range for heat treating. That was an issue for production 40 years ago. Today? Not so much. Technology and manufacturing advancements have made it possible to hold very precise temperatures while still processing materials/parts quickly. Think of it the same way as you would the cost and time to produce a color television in 1965, vs the inflation adjusted cost for an infinitely more advanced LED TV today. We just have the ability to make things both cheaper and better today (doesn't always happen, but we can)
This. 9310 is actually slightly superior to Carpenter 158 alloy, but has a narrower temperature range for heat treating. That was an issue for production 40 years ago. Today? Not so much. Technology and manufacturing advancements have made it possible to hold very precise temperatures while still processing materials/parts quickly. Think of it the same way as you would the cost and time to produce a color television in 1965, vs the inflation adjusted cost for an infinitely more advanced LED TV today. We just have the ability to make things both cheaper and better today (doesn't always happen, but we can)
tcoz
Member
I bought one of their v2 Black Nitride BCGs in January. Although it looked fine, the gas key came loose the first time I put about 50 rounds through it. I was going to a training on the following weekend and when I explained the situation to them, AIM shipped a new one out immediately and I received it in three days. No problems with this one after about 1200 rounds, some of it rapid fire. It's also very easy to clean. You're definitely GTG with AIM.
BSA1
member
Deleted. Found it.
Z-Michigan
Member
AIM has sold several different versions of AIM-branded carrier group: economy and "premium" versions, which are distinguished by the front right side of the carrier (standard radius on economy, faceted angles on premium) which also have different gas keys, gas key screws, and extractors; and phosphate, nickel-boron, and nitride treated versions. So the answer for one version may or may not apply to another.
That said, I've been using an AIM bcg, in the economy but nickel-boron coated flavor, for about a year and 900 rds in a PSA upper. I've had no problems with it, and no function issues with the upper. 900rds isn't much but it's better than zero.
Because the deals have been so good and in the recent past BCGs were as precious as diamonds, I bought a couple others. The economy phosphate version from more than a year ago has fairly poor staking. The premium versions (I have one each nickel-boron and nitride) look to have been much better assembled, and judging from appearance only do look to be premium products. I'll probably be trying out the nitride one in the near future and will post experiences when I do.
That said, I've been using an AIM bcg, in the economy but nickel-boron coated flavor, for about a year and 900 rds in a PSA upper. I've had no problems with it, and no function issues with the upper. 900rds isn't much but it's better than zero.
Because the deals have been so good and in the recent past BCGs were as precious as diamonds, I bought a couple others. The economy phosphate version from more than a year ago has fairly poor staking. The premium versions (I have one each nickel-boron and nitride) look to have been much better assembled, and judging from appearance only do look to be premium products. I'll probably be trying out the nitride one in the near future and will post experiences when I do.
USAF_Vet
Member
I've also got one in my 10.5" pistol. I've only put about a hundred rounds through it so far, still looks like it did when I cleaned it out of the box.
Ibmikey
Member
I Have at least fifteen AR's running BCG's from Aim, the niboron/ nitride unit is my favorite they list all of it's attributes in their ad. I ran it full auto with a friend's registered lower and it did not skip a beat. Cleaned right up afterward and the rifle was smoking hot while being fired. Aim warrantees their products so i have no concers about purchasing from them.
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