I have colt, psa, tool craft, and spikes bcg’s. All have never given me any issues. The bcg I want to buy next is a chromed young mfg, but I need it like a hole in the head

Before I got my ultrasonic cleaner, I was thinking about a chrome, now, I don’t care. The chrome are pretty though

Why not just use Black Nitride? The coefficient of friction between Nitride and Chrome is very close. Both are between 0.1 - 0.2

Or you can go DLC. DLC coefficient of friction is .02 - .15

Edit - That post about chrome was Circa 2010. Nitride wasn't a thing back then.

I've purchased countless carriers in my day in the pursuit of the "best". I function test all of my personal uppers that I build on our shop Daniel Defense MK18 Machine Gun. If it can run a full magazine on Full Auto then it will preform. With that being said, every carrier be it phosphate, NIB, Nitride, or DLC that I have ever tested passed. Where these coatings begin to shine is over the longevity of cleanings. I personally only buy Black Nitride Toolcraft Carriers now because, simply put, they run longer dirty. As an added bonus, they look pretty slick through the ejection port. I don't like NIB because it tends to get a black tarnish to it that makes it constantly look dirty.

If you keep a light coating of oil on the Nitride stuff carbon comes off very easily. My go to oil for lubrication on ALL of my firearms is Brad Penn 10w30. If its good enough for the race cars I've owned then its dam sure good enough for a firearm!

Yes they are. I’ve had my eye on a Young Mfg chromed bcg for quite a while now.

I vaguely recall hearing that there’s some kind of graphite(?) lube that’s designed for cold weather, but it’s been years since I’ve seen it discussed, and I’ve never been stationed in Alaska. Slip 2000 also claims that their gun lube will work down to -110 F, but I don’t recall hearing anyone talk about first hand experience with it at those temperatures.

Here's a lesson for Mr. Hat who doesn't understand that friction is a principle of physics.

Sons of liberty BCG is 114.99 at Primary arms right now.  Not bad for a Microbest BCG with sprinco extractor spring

apparently both of you need to go back to school as friction is a costant in all meta sciences...JHC are people this fking stupid?

Blain, you need to try harder and not spend half the day trying to find one small subset of a science that is based on things that have practically no bearing on your stupid ass initial post and are present in every discipline.

start with metallurgical principals of metals, nonmetals and metaloids and report back

Ok, so you're admitting now that physics is a principle of physics?  Good, progress!

Considering Blain is talking about the friction coefficient of the BC due to the finish/coating, the metallurgy (Metal Physics) of the BC is mostly, if not completely, irrelevant (since we aren't worried about the friction coefficient of the BC metal itself). We would actually need to start with tribology, which draws on many academic fields including physics. But without going down that rabbit hole, what do we all know to be true? Phosphate finishes are rougher (more friction) than Chrome (less friction). Phosphate finish is rougher because it's more porous, which also causes carbon to adhere to it much easier, which then causes more friction. Is a phosphate finish suitable for a BCG. Sure. Is it the most ideal finish? No. Does a phosphate finished BCG have a higher chance of hanging up due to dirt and debris than a Chrome plated or NiB BCG. Absolutely.

I ain't getting into a squabble but I think something is worth mentioning, 'carbon is a dry lubricant'. Carbon actually lessons friction, rather than increases friction.

Chrome, NB and Nitride are all fairly slick and require less oil than Phosphate. Phosphate holds oil better due to the rougher surface. Take that however you want.

All surfaces eventually become carbon covered if left uncleaned, so comparing the surface friction of different carrier finishes is only relevant to perfectly clean carriers. After some rounds are fired, all of the surfaces will have a film of carbon and become fairly equal. The longer the surfaces go without cleaning, the more equal they become.

Adding oil to an already carbon covered carrier actually creates less friction than any of the surfaces started with. I think most people look at a carbon covered upper and assume it is adding friction when it actually isn't. Carbon only becomes a problem when it is 'thick' enough to bind tight surfaces/tolerances.

Don't doubt the shake test!

DD makes great stuff I have zero doubts their chrome BCG is great and worth the money. However, I don’t want to spend $200 on a BCG. I am not scientific, I just spend money on other things

Graphite carbon is a dry lubricant. Not the impure “carbon” that builds up in a firearm. There are tons of impurities (unburnt powder, lead, gunpowder additives, and the list goes on) that cause more friction. Also, the surface of the carbon build up on a porous phosphate BC is going to be different than on a Chrome or NiB coated bolt.

None of it really matters if you are lubricating like you should.

Also Agree

The remnants of smokeless powder and gasses that leave the ''carbon'' in our firearms is still a dry lubricant.
Ever since I first had it explained to me, I found it interesting. Sure, nobody is scraping off gun residue and selling it as lube but the carbon left behind still has lubricating properties. It has to do with the shape of the Atoms, I'm no scientist so I don't fully grasp the science of it. What I do understand is the results of carbon building up in firearms. The carbon itself does seem to be a lube and adding oil to the carbon seems to form a very slick layer.
You make a good point about additives. I think it has more to do with sand or dirt bonding to the left over carbon and oil that can eventually add friction, not the burnt powder itself. The only time I have seen ''carbon'' do anything other than add a layer of dry lube is when it becomes thick. Once carbon builds up, it causes friction issues due to small tolerances, rather than the surface itself being rough. Small particles of foreign material bonding with the carbon will obviously be different than the ''carbon'' itself.
If you pay attention to how a firearm reacts to the carbon, you will find that it has only positive effects on friction until it becomes 'thick', as I mentioned. It's the same principle as grease, grease is also a lube but thick grease can actually add friction to tight tolerances.
My point is, the original metal surface of the carrier has less friction once a film of ''carbon'' has formed. The metal itself has more friction than the ''carbon'' layer.

The finish on a carrier has more to do with how it bonds to additives like oil and carbon than the finishes original friction.

I am not familiar with the graphite lube he mentioned, graphite was always taboo.

Before I knew better, we would just shoot ARs clean with RemOil or nothing at all if it was going be below zero.

Slip EWL after I started reading here, and Amsoil 0w20 Signature

I cold soaked 2 rifles overnight and did that test for Spikes in -15* with the Spikes Extreme lube, they never lost a beat, but they were sluggish.  I might have had issues if it had been colder, I am not sure.  It's good oil, though.

I have been very happy with my LMT enhanced bolt and enhanced carrier.  This one is used suppressed 100% of the time with no sign of being over gassed.  Ammo is typically wolf gold or Federal Xm193.  The Silencerco Saker is certainly not known as a low back pressure can either.  Buffer is a Geissele Super 42 H2.

As it happens, Brownells got the LMT Enhanced BCG in stock as of yesterday, which coincided with a 10% code (and other online incentives), so I ordered one.  I do wish they would finish the actual carrier out of something different, but to the point that many made here, it isn't likely that it will matter given the use of this AR (it won't be primary for me).  The only reason I would like an alternative coating/finish is for ease of cleaning. . . . because I'm a super-lazy, high-maintenance, spoiled baby.

I appreciate everyone's thoughts and input.  It broadened my knowledge quite a bit.  I'm going to be buying several of the other recommended BCGs as coupon codes and discounts coincide . . . and I'm looking forward to seeing the differences.