NiB barrel extensions

[MWAG19919]

Just curious, why is a NiB BCG considered bad (or at least sub-optimal due to the way it wears), but a number of respected companies offer NiB barrel extensions? I've seen NiB BCGs fall out of favor and be replaced by NP3 (or good ol' fashioned phosphate), but only one company I know of offers a barrel with NP3 extension.

[okie]

I would guess corrosion resistance, but it doesn't do anything for the exposed bit of breach face on the barrel, which I don't think has chrome on it. Could be wrong about that, though.

Ease of cleaning in another selling point. Would also stand up to the chamber brushes with steel wire on the extension side.

In all honesty, though, there's nothing wrong with the standard extensions and coatings. These special coatings cause more problems than they solve. Nickel boron once it breaks in is actually not very slick at all, and the nickel teflon coatings tend to flak off. If I had to have some special coating, I would probably choose zirconium nitride, but I have yet to see anything that's as smooth as broken in phosphate. My Mk18 cycles smooth as glass and actually did from day one even before break in.

[Todd.K]

What is wrong with your phosphate BCG and barrel extension than needs to be "fixed”?

The only thing I avoid if I can’t find phosphate is nitride. Nitride shouldn’t be used on parts with a critical case hardening process.

[markm]

Based on my NiB bolt breakage and the general sucky characteristics of the finish, I avoid it like the plague.

[AndyLate]

I have a barrel with a NiB extension. I honestly forget its coated (BA Hanson). I would neither buy or avoid barrel for a NiB coated extension. FWIW, this question was asked and answered before: https://www.m4carbine.net/showthread...rrel-extension

Andy

Edit - I have 2 barrels with NiB extensions, BA Hanson and BRT Optimum.

[Disciple]

The only thing I avoid if I can’t find phosphate is nitride. Nitride shouldn’t be used on parts with a critical case hardening process.

In the AR which parts are those?

[DG23]

These special coatings cause more problems than they solve. Nickel boron once it breaks in is actually not very slick at all, and the nickel teflon coatings tend to flak off. If I had to have some special coating, I would probably choose zirconium nitride, but I have yet to see anything that's as smooth as broken in phosphate.

LOL!




If I go pull the oldest and most used / 'broken in' Colt Phosphate carrier I have and compare -

No way in hell it will be smoother than that finish.

[okie]

LOL!




If I go pull the oldest and most used / 'broken in' Colt Phosphate carrier I have and compare -

No way in hell it will be smoother than that finish.

Just wait until it gets worn down and starts sticking.

[DwayneZ]

Does the question have context? Like 1k rnds per day vs 1k rnds per year?

Could we say for the casual shooter, most/all the finishes will last a "lifetime" ?

[MWAG19919]

Does the question have context? Like 1k rnds per day vs 1k rnds per year?

Could we say for the casual shooter, most/all the finishes will last a "lifetime" ?

Obviously we could. We could also say the casual shooter will do fine with 4140 barrels, 6061 receivers, .080” carbine gas ports, and a whole host of other bad ideas.

My context was simply this: we know the drawbacks of NiB in a BCG, yet a few highly respected companies continue to use it in barrel extensions. I’m just curious if the drawbacks (flaking, improper heat treating, increased friction with wear) show themselves less in barrel extensions or something.