I don’t get the appeal of Nickle Boron coatings.


That is rust on that bolt tail.  As you see with this bolt, Nickle Boron coated item will stain black over time.

I swear that I think all these people who say that NiB bolt carrier groups just wipe clean don’t actually shoot their firearms.

I’ve found the Ionbond/Diamondbond coatings have held up much better than Nickle Boron, but personally I don’t feel they are worth the cost.


      • Oh wow. Learn something new everyday. In my own experiance between the plain parkerized carrier and the chrome one the chrome one cleans up easier. Have you guys had any experience with the other coatings that are out there now? Always wonder if there’re legit or just hype.

        • yeah the chrome ones do seem to be faster to clean up.no doubt about that. It will eventually start to flake like Howard says. I have seen several with flaking. I have an original colt chrome BCG from the 60s that is still ok, but its in a SP1 and I dont shoot it much. I think colt didnt stop making them chrome and went to the milspec current finish for a reason. Though bores and insides of the carriers are still chrome. does make you wonder why chrome was good enough for the bore and chamber but not the other as far as durability goes

          • I heard it was something to do with hiding imperfections such as cracks in the bolt. Not sure if there was an actual problem or more just the idea of a problem.

          • the reasons for it are murky and explanations of it are multiple. I am not sure the real reasons., but as far as I know, Chrome was pulled due to both cost – and extractor failures due to hydrogen embrittlement. Some of the chrome did flake off of as Howard has said. But I am not sure how much of that affected the decision to stop using them. I will have to break out my copy of The Black Rifle and see what it has to say on the matter since it is essentially THE source on the subject of the M16 and its development

          • Author of The Black Rifle II” , Chris B. who mostly knows his stuff about the history of the M16 recently wrote this on the chromed BCGS

            “The bolt and bolt carrier had gone through some changes as well. The original AR-15 had a chrome plated bolt and bolt carrier. The XM16E1 used the same with the addition of the forward assist notches. This was a proprietary “hard” chrome plating process that was quite expensive. It was found that the chrome did wear off and chip and eventually corroded. It had also prematurely worn the internal dry film lube inside the upper receiver. The original purpose of chrome plating was to make it easier to clean. This it did, but there was a better way to go about this.

            There are no remaining records that state the exact time when the chrome plating process ceased, but it is safe to say in the 1967 time period the chrome plating was dropped in favor a more durable and cheaper manganese phosphate which was black in color. The inside of the bolt carrier and carrier key remain chrome plated. Both the smooth side as well as the forward assist notched versions of the bolt carrier was produced in chrome plating and eventually both changed to the new finish. In 1966 Colt stopped manufacturing the smooth sided carriers due to lack of interchangeability with the XM16E1/M16A1 rifles.

            Additionally, a new firing pin retaining pin was introduced. The original part was a machined retaining pin that came in chrome plated and manganese phosphate finish. A much cheaper cotter-type pin replaced this. The original was a much better component but there was another more inexpensive way to do the same job.”

          • I own one of those original retaining pins. IMHO the cotter pin is an improvement. Easier to remove, and less likely to break.

          • FYI: As early as May 1965, Colt requested permission to finish the the bolt, ejector, extractor, and extractor pin in parco-lubrite, instead of the electrolized finish. This was justified as improving wear resistance and service life of these components.

            Colt changed the finish of the bolt carrier in June 1965. The finish of the bolt carrier key, bolt, extractor, and ejector was switched over in September 1965.

            There are post-Ichord Hearings references to US Army testing of a plated “shiny bolt,” but clearly nothing came of it.

      • That sounds like a bad chrome job, and not a fault of the chrome itself. I had a set of chromed wheels on my truck that did the same thing.

        I’m still going to keep an eye on my chromed bolt & carrier.

  1. My experience is limited but they clean up faster than parkerized BCGs and that will sell. If the price difference isn’t too much it’s worth it to me, people will pay for convenience. Then there is the coo factor, we’ve all been there. Some folks are just old fashioned and not quick to jump on “improvements”, I’m still not sold on the Melonite barrels even though I think they SHOULD be as good as chrome lined ones I’m waiting to see more info having had a negative experience with a non-chrome Armalite barrel twenty years ago.

  2. What about nitride finishes on bolts and bolt carriers? They work well on barrels and pistol slides like the S&W Melonite or Glock Tenifer treatments.

    • I have a couple of diamondbond BCGs that mostly look new. The cam pin shows wear but the carrier looks almost brand new after tens of thousands of rounds.


Please enter your comment!
Please enter your name here