We have two identical M4s, except for the stocks. My wife's M4 has an LMT stock and I have a Magpul ACS-L. Everything else is the same, uppers are BCM 14.4", lowers are Spikes with the enhanced parts kit, recoil springs are LaRue, the buffers are Spikes H2, the bolt carriers are Keis, and the bolts are Fail Zero.

The rifles were stored with the safeties on but, a cartridge was in the chamber and a magazine was in the magwell. I went nuts when I saw the cartridge in the chamber but, I accept full responsibility.

When I went to clear the chambers in both weapons, the cartridges stayed attached to the bolt face. I pulled them off with a needle nose pliers and took of to the range. Using M193 Federal, neither gun would eject and was stuck in the bolt face. A log jam was caused by a follow up cartridge getting jammed. After about 10 rounds with each rifle we packed up and went home.

There was no visable lube on either BCG so I broke them down, wiped them off and soaked all the parts in Slick 2000 overnight. In the morning I went back out to the range with both rifles assembled and with wet BCGs,

One M4 worked perfectly with Federal M193 and Winchester Soft Point. The second M4 worked perfectly with the Winchester Soft Point but the original problem returned with the M193. The Winchester Soft Point is .223 and the M193 is 5.56. I shot off all of the ammo and went home.

Any thoughts?? Is the ejector ruined on one bolt? I could go back after putting a new bolt assembly in the bolt carrier.
Thanks for your help.

This message has been edited. Last edited by: mrmn50,

When you cleaned them, did you strip the bolt down and clean and lube the ejector? If not, I'd definitely try that. It certainly sound like an ejector problem.

I don't know if this could be the issue here or not, but I noticed this on Fail Zero's site, under their FAQ section:

Do FailZero parts ever need cleaning?

FailZero parts do require cleaning but at far fewer intervals then standard bolt/carrier components. Fouling can be brushed away with a steel brush with little effort. A normal cleaning schedule is suggested with FailZero parts but alcohol wipes should be all that's necessary. Do NOT use cleaning solvents that react negatively with Nickel.

http://www.failzero.com/about-...w/failzero-faqs.html

If you used a gun cleaning solvent to clean these bolts that didn't agree with the coating and with a brass cased round stuck in contact with the bolt face for a period of time.. might've something occurred?

Aparently the fail zero bolts are not foolproof.At a minimum a new ejector spring and carefully inspect ejector for burrs and straightness,clean and lube the channel,carefully reassemble with a new pin and function check.

quote:

Originally posted by Dwill104:
When you cleaned them, did you strip the bolt down and clean and lube the ejector? If not, I'd definitely try that. It certainly sound like an ejector problem.

I lubed the ejector on both and did not clean them. I did push the ejector in against the spring on both and then lubed under tension. The spring tension was very strong on both.
Thanks, I will wait before the next range session and then do as you suggested.
Still, one worked perfectly the other only with hi end ammo. I did everything the same on both.
Thank you again

My first guess based on your description of the problem was that something affected the nickel plating on the bolt face and the sides forward of the face. If the lube or whatever you used for cleaning at one time caused the plating to in effect swell, that would then “grab” the case head and tend to keep it in place and to interfere with ejection.

I don’t know a lot about current nickel plating methods, but the conventional process used to require depositing a base layer of copper to the steel and then the nickel on top of that. Because the copper could be affected by copper-removing solvents, that was the reason for the warnings, not so much that the nickel itself was affected. Even if you didn’t use any solvents yourself, metal plating has been known to deteriorate more or less on its own. I recommend taking a very close look at the bolt face to see if there are any signs of flaking of the plating or of its being rougher than it should be. Perhaps contacting FailZero would be in order.

Although you checked the ejector, I cannot imagine how anything to do with its operation would cause a cartridge to stick against the bolt face. I believe that something must have reduced the interior diameter of the bolt face to cause the very unusual problem you describe, and I’d first be suspicious of the nickel plating.

^^^^^^^^^^^^^^^^^^^^^^

Now, the problem was with both rifles. After cleaning and lubing, one was still failing. Could it be a matter of time before both are failing.?
I will check the bolt face tomorrow.
Thanks, me boy.

I just might replace both NiB bolts with AIM Nitrided bolts, which is what I have for back up.
There should be no problem with electrolosis, should there??

Good night until tomorrow.

quote:

Originally posted by mrmn50:
^^^^^^^^^^^^^^^^^^^^^^

Now, the problem was with both rifles. After cleaning and lubing, one was still failing. Could it be a matter of time before both are failing.?
I will check the bolt face tomorrow.
Thanks, me boy.

I just might replace both NiB bolts with AIM Nitrided bolts, which is what I have for back up.
There should be no problem with electrolosis, should there??

Good night until tomorrow.

The fact that the same problem occurred with both rifles that (presumably) have identical bolts just makes me more suspicious about the plating. It’s quite possible, though, that cleaning removed a bit of offending material from the one bolt and resolved the problem—for now. You could try lightly scraping the bolt face area with something like a paper clip to see if it affects the plating as well.

I don’t know enough to comment whether some other process might have been involved.

I have decided to contact Fail Zero about the problem. In the meantime I am going to pop new bolts into each M4 and try to work out some kind of credit with Fail Zero and use them as backup.
BTW, it was the plating and both bolt facings were effected .
Thanks to all of you for your wonderful help.

Thank you for the update. It’s always helpful to know how these things turn out.

quote:

Originally posted by sigfreund:
Thank you for the update. It’s always helpful to know how these things turn out.

Agree. This is a new problem to me as well. I'd like to know what Fail Zero has to say about this (though if it's an accelerated corrosion issue, then it's likely to affect most if not all nickel-boron parts regardless of manufacturer). Thanks for keeping us up-to-date.

I have NiB BCGs as well.

Interesting! Did you only use the Slick2000 and do you believe that it was causing the issue with the Nickle on the Zero Fail BCGs? Or something else?

I own a couple Fail Zero AR15/M4 Firing Pins, looking it up I see that they say "This EXO Nickel Boron coated firing pin provides a permanently lubricious surface for extreme durability and increased wear and corrosion resistance." I haven't had an issue yet, now I'll be thinking about it all the time:-) I tend to do a coating of Mobile 1 over all kinds of different cleaners depending how it looks. (Hoppes, Hornady, Break Free and a bunch of other stuff which I forget now). Rarely take the BCG apart when I clean, just wipe it off and Mobile one it, stuff it back in there.

1- I will follow up asap when I get a resolution with Fail Zero.

jimb888 - In my OP, I describe what I think caused the problem, a cartridge in the chamber adhering to the bolt face for maybe six months. I think it may have jammed the ejectors back and, in retrospect, there may have been some electrolosis on the bolt facings. The last part is just a guess.

Thanks for the heads up on the Fail Zero bolts. I have one of their BCGs, and now I have no intention of using it as I'm not interested in constantly having to worry about whether the cleaning product I use is compatible with the nickel plating. I'll stick to the normal stuff that works with all of my normal gun cleaning stuff.

quote:

Originally posted by Dwill104:
Thanks for the heads up on the Fail Zero bolts. I have one of their BCGs, and now I have no intention of using it as I'm not interested in constantly having to worry about whether the cleaning product I use is compatible with the nickel plating. I'll stick to the normal stuff that works with all of my normal gun cleaning stuff.

I do not see the Bolt Carrier as a potential problem. Also, remember, the cleaning solution was not the cause of the problem.

Also, I have found out the NiB BCGs need lubing more frequently.

quote:

Originally posted by mrmn50:

quote:

Originally posted by Dwill104:
Thanks for the heads up on the Fail Zero bolts. I have one of their BCGs, and now I have no intention of using it as I'm not interested in constantly having to worry about whether the cleaning product I use is compatible with the nickel plating. I'll stick to the normal stuff that works with all of my normal gun cleaning stuff.

I do not see the Bolt Carrier as a potential problem. Also, remember, the cleaning solution was not the cause of the problem.

Also, I have found out the NiB BCGs need lubing more frequently.

When I say BCG, I mean the full group including the bolt and carrier. Understand it's the bolt that had your problem, but I don't intend to buy a new bolt and stick into the Fail Zero carrier.

Surprising to hear that the NiB BCGs need more lube. Isn't one of the selling points that it requires less lube?

quote:

Originally posted by Dwill104:

quote:

Originally posted by mrmn50:

quote:

Originally posted by Dwill104:
Thanks for the heads up on the Fail Zero bolts. I have one of their BCGs, and now I have no intention of using it as I'm not interested in constantly having to worry about whether the cleaning product I use is compatible with the nickel plating. I'll stick to the normal stuff that works with all of my normal gun cleaning stuff.

I do not see the Bolt Carrier as a potential problem. Also, remember, the cleaning solution was not the cause of the problem.

Also, I have found out the NiB BCGs need lubing more frequently.

When I say BCG, I mean the full group including the bolt and carrier. Understand it's the bolt that had your problem, but I don't intend to buy a new bolt and stick into the Fail Zero carrier.

Surprising to hear that the NiB BCGs need more lube. Isn't one of the selling points that it requires less lube?

True, that is what they say. But, when lubing, the lube does not adsorb into the metal and therefore, dries out quicker.

For me, I do not see a problem with putting a non NiB bolt into a NiB carrier. Only time will tell.

quote:

Originally posted by mrmn50:
True, that is what they say. But, when lubing, the lube does not adsorb into the metal and therefore, dries out quicker.

Unrelated to the finishes you are discussing, but IonBond absorbs oil like a sponge. This may also be the case with your NiB plating. But IonBond also works well dry, so to speak. I keep it oiled, but don't worry about the fact that the oil disappears.
 

Back in the 80's we had a few chrome plated bolt carrier groups. Both the carrier and bolt were plated. There was a safety memo from TACOM stating that the plated parts were not authorized OCONUS, meaning overseas. I never was able to get a straight answer as to why you couldn't take these weapons out of the US, but now I'm seeing a possible reason why.

I'm reading between the lines here that it probably isn't a good idea to keep an AR chambered with a round for the long term? I.e., in general, is this a problem or issue?

I understand that the bolt face finish was the culprit in this particular case. This is the first time that I've even considered that having a round kept in chamber long term could be a set up for a problem.