Need Help choosing a Bolt Carrier Group for my 300 Blackout

[ToiddRvs]

I am in the process of finishing my 300 Blackout build, all I have left is the sight and the bolt to purchase, I saw an advertisement for a Nickle Boron Bolt Carrier Group for $99.00 shipped. In the description it states for .223/5.56/300 Blackout and is made with 9310 Bolt Material; 8620 Chrome lined carrier and gas key. Also from this company there is a complete bolt carrier group listed for $79.00 shipped. It also has is made of 9310 Bolt Material; 8620 Chrome lined carrier and gas key. The difference is in the descriptions it only lists the .223/5.56 and not the 300 Blackout.

Now I understand that the 300 Blackout should work with a standard M16/AR15 Bolt Carrier Group, yet this bolt only advertises as being compatible with .223/5.56. The only difference I see between the 2 bolts is one is Nickle Boron and the other one is not. Also what is the advantage of having a Nickle Boron Bolt over a non Nickle Boron Bolt.

As for the sights I have decided to go with the Leopold 300 Blackout Sight. It is supposed to be factory zeroed for the most popular 300 Blackout Loads.

What does the board think

Thanks

[MosquitoArms]

By chance are you talking about AIM Surplus?? All their BCG's are going to work perfectly. They're well known and reputable. You could get the budget BCG ($79.xx) and be perfectly functional and happy.

The BCG with the description "300 Blackout" is, as you suspect, just the same as the others. The 300 AAC Blackout cartridge uses standard AR15/M16 BCG's (bolt and all).
And, it is indeed weird to see AIM Surplus put that in the description. I assume it's to attract & reassure new-comers.

Nickel Boron? Compared to the standard phosphate finish of most BCG's, it's a bit easier to clean and will run slightly smoother when not lubed properly or dirty. And, when I say "smoother", I mean "less likely to fail to lock the bolt back on last shot" and/or "less likely to fail to feed".
But, I prefer AIM's Black Nitride (aka: Melonite, QPQ, Ferritic Nitrocarburization) BCG. Black Nitride is a surface hardening treatment, not an actual coating like NiB (Nickel Boron) or even Chrome lining (correct me if i'm wrong, gurus).
Many people claim that Black Nitride BCG's are even easier to clean and "slicker"/smoother than NiB BCG's (but not as easy as hard chrome BCG's...but that's a mirror finish for you..)

AIM sells an "upgraded" BCG with a Black Nitride finish for $99 (shipped). But, they're currently sold out, and they sell out quickly every time they get a shipment (every few weeks). But, it's my top recommendation. Best value...AND LIFETIME WARRANTY!!!!!
AIM V2 Black Nitride BCG

[randyrucker]

NiB is a good way to go. Lots of good NiB BCG's out there less than $120. Here is another thread that might give you more info:

viewtopic.php?f=136&t=90875

[tallburnedmidget]

If you plan to shoot suppressed you get a lot of dirt and grim on the BCG, that is the nature of shooting suppressed. With this bit of understanding an NiB makes things much easier to clean and gives you more reliable function for a longer period of time between cleanings.

For 300BLK I would recommend NiB because I cannot seeing anyone resisting the ability to shoot subsonic suppressed when it is as easy as switching the ammo and when they see it happen in person or really check out the youtube videos.

Also I use the same scope on my 16" 300BLK. It works pretty well and the tactical turrets allow you to quickly adjust for different loads that are in the ballpark but not right no. Just shoot a lot and write down your turret numbers for your loads on a card and keep it with you. You can then switch with easy. I took 3 deer subsonic and 1 supersonic last year with that scope no adjustments, using just the reticle marks and a lot of trigger experience. Other than my battery draining it is top notch. I just flip the battery around when not in use to solve that problem

Hope this helps

[rjacobs]

I personally wont run anything but a C158 bolt. Lots of folks saying "9310 is JUST AS GOOD as C158". I dont know, I am not a metallurgist, but 9310 is cheaper than C158 and easier to machine. Both of those things lead me to think 9310 is inferior to C158. I know C158 is considered a "strategic material" or something like that and you have to have the proper licensing just to be able to buy it. There is a reason all the top tier guys(Colt, BCM, Noveske, LMT, AAC, Daniel Defense, etc...) only use C158 bolts.

If its a gun you are going to shoot a lot, I would stick with C158. If its a gun that wont see more than a couple hundred rounds a year, 9310 is probably OK.

Palmetto State has their "premium" BCG's with C158 bolt thats MPI/HP tested for 99 for the no logo and 109 for the logo. I say save the 10 bucks.

As far as nickle boron, I am not sold on it, especially for a bolt. Read R. Silvers thoughts on most Nickle Boron coated parts. If I remember reading correctly he says most stuff doesnt take into account that particular coating for tolerances and instead uses the tolerances for a parkerized part which isnt the same as nickle boron. I also have read a few things about the nickle boron process causing parts(bolts in particular) to become brittle and break lugs off prematurely. I think I would be ok with it for a carrier, but not necessarily a bolt.

[DoubleJ]

Carpenter steel isn't the best steel for the AR bolt, it's just the mil spec steel. As far as coatings, I've got bolts and carriers in NiB, phosphate, TiN, and hard chrome. NiB wins all contests hands down, except for price. Anything suppressed id do all NiB. Anything not, I'd do NiB bolt and phosphate carrier.

[MosquitoArms]

Yah, C-158 is just the mil standard, just like the phosphate finish found on most BCG/bolts.

I've got AIM's V2 bolts in both 9310 and C-158...and NiB and Black Nitride for that matter.
Some claim that 9310 isn't as good due to a lower surface hardness (experts?), but
that no longer matters when you coat it with NiB, Hard Chrome, or treat with Black Nitride (aka: melonite, ferritic nitrocarburization, QPQ, ____).

[wtrski76]

If you're suppressing, get a NiB coated setup - much easier to clean. I have a standard BCG in one rifle and a NiB in another and much prefer the NiB since most of my shooting is done suppressed. Just bought a WMD NiB setup for a new upper I'm building as well.

[afshirt]

Supposedly 9310 is cheaper than C158 because of the amount that has to be ordered at one time. There is a huge writeup of the difference posted up on m4carbine.net. Me personally C158 has worked for the military for how many years? My job in the AF for 18 years was small arms repair. You would occasionally see the lug to the left or right of the extractor break but that was few and far between. a C158 that has been tested from a reputable company is all you need. As far as compatibility with blackout, it is the exact same casing so it must work.

[Pointnpull]

By chance are you talking about AIM Surplus?? All their BCG's are going to work perfectly. They're well known and reputable.

I put an AIM Surplus NiB BCG in my BLK. It feels oiled even when dry, it's so smooth, and about all you need to clean it after a couple hundred rounds, is a damp rag. I looked on their site, but can't find the one I bought. I gave about $125 for mine. I highly recommend it.