So bcg in nickle boron or hard chrome

[pyrotechnic]

Yes, chrome has micro cracks. As to the effect on bolts, I have no clue.

However, the nib surface of markms bolt I checked out had cracks especially around the corners of the lugs and I suspect that is why it failed.

I'd like to clarify, my skepticism of chrome plated bolts was not intended to be an endorsement of the NiB coating.

[ABNAK]

I have liked the Young Chrome bolt and carriers I have had. They do not stake them, but if you buy it from Rainier they stake for you.

I feel it cleans easier, and I like easily being able to discern whats clean because it is chrome and not black.

I have had WMD NIBx a LMT enhanced carrier for me. I have used it a lot and nothing has flaked off, it has stained though. I think he staining was left by rand CLP burned on their. The rand clp has been total junk for me, it sets up like glue if stored on a fire arm for too long.

I have a Rainier match BCG that is NiB, I never ended up running because I think he bolt is going to break some time. Just too many reports of it causing problems.


I also have a few LMT Enhanced bolts, what ever is on there is great. Any one know what it is? NP3? LMT is mum about it but I *think* it is nickel-based

Anyway, I found chrome to be just as good as the other ones and have no reported down sides. So why not get chromed BCG even if an incremental improvement? Its only an incremental price increase.

Yep, just as important (to me) as easier cleaning is the fact that you can SEE what's still dirty, namely in the infamous bolt tail area.

Other than the two LMT Enhanced BCG's I own (which of course there's no reason to), I have had all my bolts hard chromed by Metaloy. Not the carriers themselves, but the bolts. I figure the bolt is the "piston", and every piston in relatively modern military-style weapons is hard chromed. I even had the bolt in my new KAC SR15 chromed.

[ABNAK]

I am personally leery of chrome plating on bolts as fatigue appears to be the primary failure mechanism for that part. To my understanding chrome surfaces have cracks inherent to the plating process which would provide initiation points for fracture. The only peer reviewed paper I was able to find via a quick Google search on the subject of chrome plating and endurance limits was from 1949, it mentioned a marked reduction in endurance limits of plated specimens vs unplated ones. However, I am sure that processes have come a long ways since then so its results may not applicable.

Hopefully someone who is more knowledgeable of chrome plating and it's effects on engineering materials can chime in.

While certainly not nearly on the same engineering plane as Tom12.7, I can relate my conversation with Chris Peters of Metaloy (where I've sent all my bolts for hard chroming). Before I sent my first one I spoke to him at length about the "hydrogen embrittlement" issue which I believe you are alluding to. It's been a few years and the exact details elude me but Chris kind of politely bristled when I mentioned hydrogen embrittlement. He basically said that anyone chroming today who knew what the hell they were doing would not run into that issue, i.e. it *should* be a given with today's technology and processes that HE is a non-issue. It involves a certain window of time between cooling and plating (or something like that; like I said it's been a few years).

Something chromed during the 1950's or 1960's? Might have issues. Something done > 2000? Worry not if they're worth their salt.

[dmd08]

I'm curious about Geissele's new Picatinny DSL-like coating they just announced.

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[MegademiC]

While certainly not nearly on the same engineering plane as Tom12.7, I can relate my conversation with Chris Peters of Metaloy (where I've sent all my bolts for hard chroming). Before I sent my first one I spoke to him at length about the "hydrogen embrittlement" issue which I believe you are alluding to. It's been a few years and the exact details elude me but Chris kind of politely bristled when I mentioned hydrogen embrittlement. He basically said that anyone chroming today who knew what the hell they were doing would not run into that issue, i.e. it *should* be a given with today's technology and processes that HE is a non-issue. It involves a certain window of time between cooling and plating (or something like that; like I said it's been a few years).

Something chromed during the 1950's or 1960's? Might have issues. Something done > 2000? Worry not if they're worth their salt.

Hydrogen embrittlement is easy to avoid, but you still see it occasionally. Like any other process, things happen. Guys in their garage can successfully plate stuff, and you have "reputable" vendors putting out stuff that flakes (flaking = complete failure)

Point is, buy good parts from vetted sources and you shouldn't have an issue. It's all process control and quality assurance.

[ScottsBad]

I'm curious about Geissele's new Picatinny DSL-like coating they just announced.

I was thinking the same thing when I saw the G Man (geissele not government) showed the NCC process coated carrier. That might be something I'd give a try. Otherwise, I'm fine with BCM Phosphate coated BCGs.

I still have not seen a compelling reason to run NP3, Chrome, or any other coating. Is it just to make it easier to clean? Pffft.

[Mrgunsngear]

I'm curious about Geissele's new Picatinny DSL-like coating they just announced.

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Well I'll be shooting a couple rifles with them on full auto until the guns die. So we shall find out

[opngrnd]

I was thinking the same thing when I saw the G Man (geissele not government) showed the NCC process coated carrier. That might be something I'd give a try. Otherwise, I'm fine with BCM Phosphate coated BCGs.

I still have not seen a compelling reason to run NP3, Chrome, or any other coating. Is it just to make it easier to clean? Pffft.

Short version:I know phosphate mil-spec stuff is good, and coatings aren't a must-have. But if for the price difference of a couple mags worth of ammo I can get a coating that extends service life between cleaning, lubricating, etc, it's hard to find a downside provided the coating has been vetted by enough people before I give it a whirl. (I'd feel differently if I was purchasing literally dozens of BCG's)

[MegademiC]

Short version:I know phosphate mil-spec stuff is good, and coatings aren't a must-have. But if for the price difference of a couple mags worth of ammo I can get a coating that extends service life between cleaning, lubricating, etc, it's hard to find a downside provided the coating has been vetted by enough people before I give it a whirl. (I'd feel differently if I was purchasing literally dozens of BCG's)

Can you link to the data showing what coatings extend "service life" between cleaning and lubing, and by how much?

[opngrnd]

Nope.

The key word in my post was the word "if". The way I see it, if it doesn't make it worse and it possibly makes it better, no harm in trying it. If you don't like it you can go back to standard BCG's, but if you do like it, drive on.

In personal experience, my BCM Cerakote MicroSlick BCG stays slick longer than the BCG in my Colt 6920. But even that's not apples-to-apples. My personal interest is more towards corrosion resistance than lube or cleaning, though that's not really a needed feature either. For example, I'm not at all concerned that the LMT E-carrier I recently bought isn't NP3, MicroSlick, etc, but it'd be neat if it was. FWIW, the middie the MicroSlick BCG is in hasn't been cleaned in over 2500 rounds, and is doing great, though a standard BCG would probably be the same since I do add lube periodically.