Written by someone smarter and more knowledgeable on the subject than I:
“In my experience, Nickel Boron (NiB) is an inferior coating for the AR Bolt, Extractor, and Carrier. It's a downgrade on all levels. It's a bill of goods that many companies sold, and now can't back off of without looking like a bunch of smut peddlers.
I rarely have dimensional issues with Phosphate Finished/Chrome Lined AR Bolt Carriers, or Phosphate Coated Bolts from reputable Manufacturers.
For many years I have observed reliability problems from Carriers treated with NiB. Most issues were related to a lack of Lubricant or Carrier Keys coming loose.
If you Gauge the claw recess in a NiB Extractor, they can often have a narrow or shallow Extractor Groove. This causes the Extractor to not grab the Casing Rim fully on some Brands of Ammunition, and can lead to extraction problems. The Bore in the Extractor for the Extractor Pin can also be undersize and cause Extractor binding.
The estimates below are compiled from AR's I have Serviced as a Gunsmith, and observed while teaching students my AR Technical Classes. The main failure I see with NiB is Short Headspace. About 10% fail a .223 GO Gauge (1.4636) and about 30% fail on the 5.56 GO Gauge (1.4646).
There is a difference between a 5.56 GO Gauge and a .223 GO Gauge as stated above and I test them accordingly.
I have three redundant sets of Headspace Gauges to confirm that it is not the Gauges causing my observations.
The Barrels are not the cause of the Headspace issues because I use a PTG Barrel Extension Headspace Gauge, and I can switch to a Phosphate Bolt and they pass the GO Gauges without issue.
It used to be rare to see these issues from Factory Built Uppers and NiB BCG's, and were almost always from franken-guns that were assembled by the owner or someone else. Now I see problems across the board no matter the provenance.
A well known Gas Piston AR Manufacturer recently stopped using NiB on their Bolts after years of touting how great NiB is. They have now switched to Phosphate Bolts. They stated the reason for the change was dimensional/tolerance issues. They still use NiB on their Carriers at this time. Odd that is took that long to figure that out.
Im not selling BCG's, or Gauges so if you think Im selling something, let me stop you now. If you ignore my advice, so be it. I benefit not one bit if you listen, nor am I harmed if you ignore my advice. My goal is to help those who will listen to experience, so here it goes.
My advice is:
Stop buying NiB treated AR Bolts and Carriers for your AR Builds or Spare Parts.
If you have builds with NiB Bolts, PLEASE buy a GO Headspace Gauges and check your headspace before shooting your build. If you had someone build it, ask if they used a GO Gauge, if they didnt buy your OWN GO Gauge and check it.
If you do find a setup with short headspace the best remedy is to see if another KNOWN GOOD Bolt reads the same. This is a cheap way to troubleshoot to confirm the problem is the Bolt and not the Barrel. If you confirm the Bolt is the problem then just replace the Bolt. If you insist on using a NiB Bolt, that has short Headspace, it can be hand lapped to the Barrel Extension, but that can so south FAST if you dont know what you are doing.
One possible sign that you may have a short headspace issue is hard to manually extract a chambered and unfired round using the charging handle.
There are other issues with NiB treated BCG's such as:
1) Some NiB Bolts and Extractors are brittle. This leads to chipping and premature cracking around the Cam Pin Bore in the Bolt, Premature Bolt Lug breakage, premature Extractor Failure.
2) The Manufacturers advertise NiB as not needing lubrication. In my experience they do, especially where the Gas Rings reside. If you fail to lubricate near the Gas Vents in the Carrier, the combination of carbon/firing residue, the Gas Rings, and the NiB react and lock the BCG up quite well if you let the weapon sit for a few weeks. If you hard charge the gun or mortar it, you can usually free it up, but its no where near superior to a Phosphate/Chrome Lined Bolt Carrier.
3) Many of these NiB Manufacturers treat the Bolt Carrier with NiB AFTER they torque & stake the Carrier Key Screws. When this is done, the NiB treatment often causes the Carrier Key Screws to break or loosen with use. In some cases they corrode heavily at the threads. When this happens it fails create a good seal between the Carrier Key and Bolt Carrier. If you have BLACK Carrier Key Screws (Not treated with NiB) then they were likely assembled AFTER the NiB was applied, this is best. I am also seeing more YFS Marked Carrier Key Screws in NiB Carriers. These Bolts are of poor quality and should not be used on an AR Carrier Key.
4) Some of the NiB Carrier Key and Bolt Carrier Bores appear to be from batches that were destined for Chrome Lining. My theory is the bores are oversize to accommodate for the chromes thickness and don't play well with the dimensions NiB adds to the operating surfaced. By troubleshooting problem BCG's, I have found the Gauge Specs to test these dimensions. Carrier Key Bores and NiB Carriers fail my Gauges 10 to 1 when comparing the failure rate of Phosphate/Chrome Lined Carrier & Carrier Keys. For what it's worth, I see similar issues with Nitride BCG's.
5) Manufacturers often tout how easy NiB is to clean, but in my experience an AR does not need to be stripped and cleaned after each trip to the range. Its not necessary and doing it excessively can lead to owner induced damage and/or wear. Just add lube and carry on till it's time to do maintenance, or if the weapon is subjected to outside contaminates that can lead to reliability issues.
6) In my experience NiB coating tends to shed lubricant instead of letting it lay on the surface like Phosphate/Chrome Lined BCG's allow. Very few broken in NiB BCG's come close to being as smooth as a Phosphate/Chrome Lined BCG when lubricated properly (which means generously lubricated).
God Bless Eugene Stoner and Jim Sullivan's Masterpiece. Lead not his disciples to perform blasphemous deeds to their AR.”
“In my experience, Nickel Boron (NiB) is an inferior coating for the AR Bolt, Extractor, and Carrier. It's a downgrade on all levels. It's a bill of goods that many companies sold, and now can't back off of without looking like a bunch of smut peddlers.
I rarely have dimensional issues with Phosphate Finished/Chrome Lined AR Bolt Carriers, or Phosphate Coated Bolts from reputable Manufacturers.
For many years I have observed reliability problems from Carriers treated with NiB. Most issues were related to a lack of Lubricant or Carrier Keys coming loose.
If you Gauge the claw recess in a NiB Extractor, they can often have a narrow or shallow Extractor Groove. This causes the Extractor to not grab the Casing Rim fully on some Brands of Ammunition, and can lead to extraction problems. The Bore in the Extractor for the Extractor Pin can also be undersize and cause Extractor binding.
The estimates below are compiled from AR's I have Serviced as a Gunsmith, and observed while teaching students my AR Technical Classes. The main failure I see with NiB is Short Headspace. About 10% fail a .223 GO Gauge (1.4636) and about 30% fail on the 5.56 GO Gauge (1.4646).
There is a difference between a 5.56 GO Gauge and a .223 GO Gauge as stated above and I test them accordingly.
I have three redundant sets of Headspace Gauges to confirm that it is not the Gauges causing my observations.
The Barrels are not the cause of the Headspace issues because I use a PTG Barrel Extension Headspace Gauge, and I can switch to a Phosphate Bolt and they pass the GO Gauges without issue.
It used to be rare to see these issues from Factory Built Uppers and NiB BCG's, and were almost always from franken-guns that were assembled by the owner or someone else. Now I see problems across the board no matter the provenance.
A well known Gas Piston AR Manufacturer recently stopped using NiB on their Bolts after years of touting how great NiB is. They have now switched to Phosphate Bolts. They stated the reason for the change was dimensional/tolerance issues. They still use NiB on their Carriers at this time. Odd that is took that long to figure that out.
Im not selling BCG's, or Gauges so if you think Im selling something, let me stop you now. If you ignore my advice, so be it. I benefit not one bit if you listen, nor am I harmed if you ignore my advice. My goal is to help those who will listen to experience, so here it goes.
My advice is:
Stop buying NiB treated AR Bolts and Carriers for your AR Builds or Spare Parts.
If you have builds with NiB Bolts, PLEASE buy a GO Headspace Gauges and check your headspace before shooting your build. If you had someone build it, ask if they used a GO Gauge, if they didnt buy your OWN GO Gauge and check it.
If you do find a setup with short headspace the best remedy is to see if another KNOWN GOOD Bolt reads the same. This is a cheap way to troubleshoot to confirm the problem is the Bolt and not the Barrel. If you confirm the Bolt is the problem then just replace the Bolt. If you insist on using a NiB Bolt, that has short Headspace, it can be hand lapped to the Barrel Extension, but that can so south FAST if you dont know what you are doing.
One possible sign that you may have a short headspace issue is hard to manually extract a chambered and unfired round using the charging handle.
There are other issues with NiB treated BCG's such as:
1) Some NiB Bolts and Extractors are brittle. This leads to chipping and premature cracking around the Cam Pin Bore in the Bolt, Premature Bolt Lug breakage, premature Extractor Failure.
2) The Manufacturers advertise NiB as not needing lubrication. In my experience they do, especially where the Gas Rings reside. If you fail to lubricate near the Gas Vents in the Carrier, the combination of carbon/firing residue, the Gas Rings, and the NiB react and lock the BCG up quite well if you let the weapon sit for a few weeks. If you hard charge the gun or mortar it, you can usually free it up, but its no where near superior to a Phosphate/Chrome Lined Bolt Carrier.
3) Many of these NiB Manufacturers treat the Bolt Carrier with NiB AFTER they torque & stake the Carrier Key Screws. When this is done, the NiB treatment often causes the Carrier Key Screws to break or loosen with use. In some cases they corrode heavily at the threads. When this happens it fails create a good seal between the Carrier Key and Bolt Carrier. If you have BLACK Carrier Key Screws (Not treated with NiB) then they were likely assembled AFTER the NiB was applied, this is best. I am also seeing more YFS Marked Carrier Key Screws in NiB Carriers. These Bolts are of poor quality and should not be used on an AR Carrier Key.
4) Some of the NiB Carrier Key and Bolt Carrier Bores appear to be from batches that were destined for Chrome Lining. My theory is the bores are oversize to accommodate for the chromes thickness and don't play well with the dimensions NiB adds to the operating surfaced. By troubleshooting problem BCG's, I have found the Gauge Specs to test these dimensions. Carrier Key Bores and NiB Carriers fail my Gauges 10 to 1 when comparing the failure rate of Phosphate/Chrome Lined Carrier & Carrier Keys. For what it's worth, I see similar issues with Nitride BCG's.
5) Manufacturers often tout how easy NiB is to clean, but in my experience an AR does not need to be stripped and cleaned after each trip to the range. Its not necessary and doing it excessively can lead to owner induced damage and/or wear. Just add lube and carry on till it's time to do maintenance, or if the weapon is subjected to outside contaminates that can lead to reliability issues.
6) In my experience NiB coating tends to shed lubricant instead of letting it lay on the surface like Phosphate/Chrome Lined BCG's allow. Very few broken in NiB BCG's come close to being as smooth as a Phosphate/Chrome Lined BCG when lubricated properly (which means generously lubricated).
God Bless Eugene Stoner and Jim Sullivan's Masterpiece. Lead not his disciples to perform blasphemous deeds to their AR.”
