Cracked AR Bolt carrier

[PiratePast40]

I posted this on another forum but thought I should also post it here as a PSA:
While cleaning an ar15, noticed that the bolt carrier had a crack on both sides. The crack is just aft of the firing pin retaining pin. It's where there is a slight reduction of diameter on the carrier. This is pretty much a general purpose gun used for plinking, drills, range events, and some sage rat shooting. Gun has 7-8k rounds though it. Not suppressed so no unusual stress or pressures. Has a 16" Faxon gunner barrel and an ACT/ALG trigger. BCG was purchased through Wilcon Combat but there is no logo. It's chrome lined and the semi-auto version.

There doesn't seem to be any elongation, cracks, or excessive wear on the cam pin hole. One of the gas rings on the bolt fell off during cleaning but there doesn't seem to be any other unusual wear on the bolt. Will go ahead and get a new BCG and get a rebuild kit for the bolt and keep it as a spare. Looks like Toolcraft has good prices on their Chrome phosphate as well ad DLC and nickel boron coated versions.

This isn't a complaint, just a heads up that parts do wear out. I haven't heard of many instances of a carrier actually cracking so though others might appreciate the heads up. We were also examining a friends M&P AR-15 due to light strikes and discovered that his carrier group is also cracked at the same location, just not as bad as mine.

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[solv3nt]

I'd give Wilson Combat a call.

 

[kmk1012]

That's pretty interesting. I wonder what would happen if it came apart while firing. Hopefully it would stay within the upper and not do any damage.

 

[PiratePast40]

I'd give Wilson Combat a call.

Hadn't even considered calling them, but, believe it not, I found the receipt from 2016 and gave them a call. The guy on the phone was pleasant and helpful. When I said I was guessing it was 5-8k rounds, he said he'd have to call his manager. They decided that's a decent life for a BCG and it had performed as expected. These are wear parts after all. I imagine the guys are having a good laugh about the customer that called about an 8 year old BCG with 5-8k rounds down the pipe and expected a replacement!

It was on sale for $99.57 when I bought it in 2016. I feel pretty good that I can get a chrome phosphate Toolcraft for the same price today. Might even spring for the DLC this time but, to be honest, not sure if that really makes any difference in the scheme of things. Heck, if I really want bling, can go for the nickel or titanium coating.

 

[PiratePast40]

Have to come back and explain what happened. As I mentioned, I also posted on a rather uncivilized forum where the members are, shall we say, not so kind, when pointing out mistakes. There were several people that were eager to point out the error of my ways.

It seems there is a change in machining at that particular point of the carrier and, on some, it leaves what appears to be a line around the carrier at that point. The irregular line, that looked like a crack, was actually carbon buildup on that transition. After letting the Gunscrubber sit for a longer period of time, and then scrubbing with a nylon brush, the jagged edges went away. It's not a crack after all. I was wrong, so the earth can now continue to rotate on it's normal axis as before!

 

[gmerkt]

Well, interesting stuff. When I saw the thread title, I wondered, "how can one of those break?" I guess anything is possible, but I'd think of the carrier key breaking off or the cam hole area cracking where a lot of force is applied. But my AR's have never fired more than a few thousand rounds.

 

[User 1234]

In all my years of using decades old M-16s, CAR-15, and M-4's in the military I never saw a cracked bolt carrier. I am surprised that Wilson Combat told you that was normal wear and tear.

 

[solv3nt]

Have to come back and explain what happened. As I mentioned, I also posted on a rather uncivilized forum where the members are, shall we say, not so kind, when pointing out mistakes. There were several people that were eager to point out the error of my ways.

It seems there is a change in machining at that particular point of the carrier and, on some, it leaves what appears to be a line around the carrier at that point. The irregular line, that looked like a crack, was actually carbon buildup on that transition. After letting the Gunscrubber sit for a longer period of time, and then scrubbing with a nylon brush, the jagged edges went away. It's not a crack after all. I was wrong, so the earth can now continue to rotate on it's normal axis as before!

So you dropped the ball on this one?

 

[PiratePast40]

So you dropped the ball on this one?

Why yes, yes I did.

 

[monkeybutler]

Have to come back and explain what happened. As I mentioned, I also posted on a rather uncivilized forum where the members are, shall we say, not so kind, when pointing out mistakes. There were several people that were eager to point out the error of my ways.

It seems there is a change in machining at that particular point of the carrier and, on some, it leaves what appears to be a line around the carrier at that point. The irregular line, that looked like a crack, was actually carbon buildup on that transition. After letting the Gunscrubber sit for a longer period of time, and then scrubbing with a nylon brush, the jagged edges went away. It's not a crack after all. I was wrong, so the earth can now continue to rotate on it's normal axis as before!

That was my suspicion.

 

[Kruel J]

In all my years of using decades old M-16s, CAR-15, and M-4's in the military I never saw a cracked bolt carrier. I am surprised that Wilson Combat told you that was normal wear and tear.

Same. Amd 5-8k rounds? Barely broke in, that BC should go 10x that as long as it isn't in a SF setup.


Toolcraft sounds pretty good right about now.

 

[Towhead]

I saw your post.

You got off light.

 

[TTSX]

Mount Saint Helens turned out to be a pop rock

 

[PiratePast40]

I saw your post.

You got off light.

You're right, could have been a lot worse. Funny thing is, nobody suggested that it might be carbon buildup on that transition area.

 

[ilikegunspdx]

Duct tape will fix it.

 

[monkeybutler]

You're right, could have been a lot worse. Funny thing is, nobody suggested that it might be carbon buildup on that transition area.

Like me they probably looked at the pictures and did not notice any crack, just some wear and discoloration.

 

[Pepe-lepew]

Pictures are too blurry to see a crack. You sure is is not just the machining mark where the tail was turned down? There is no tension stress in that area to cause a crack. The tail is always in compression against the buffer.

 

[3MTA3]

I've gotten to the point where I only use SOLGW or Sionics bolt carrier groups and their bolts. Both are made to the same spec by Microbest and every single bolt is MPI and HPT tested. Most manufacturers only do those tests on lot samples not every single one.

For about $50 more than the hundred dollar specials they are a smoking value for a duty/go to war grade BCG. School Of The American Rifle rates these very highly and they are very efficient with perfect gas key and bolt tail/gas ring interfaces. There are more expensive BCG's out there but at twice the price or more are only marginally better.

Just my 2 cents the next time you are in the market for a bolt or BCG.

 

[Duneblaster]

AR15 bolt carriers are a weaker design compared to M16 bolt carriers. Unless they're "enhanced" and have steel that completely covers the firing pin. This is a big weak spot and your bolt carrier cracked right in this area. They will vary on how much material is removed depending on who made the bcg. I'd guess your bolt carrier had too much steel removed.

Similar to the old Beretta M9 locking block lugs that used to shear off. And the weak spot where the slide cracks. The clones coming out of Turkey are the older M9 design. They don't have the slide stop that prevents it from flying back at you if/when it breaks.

 

[monkeybutler]

AR15 bolt carriers are a weaker design compared to M16 bolt carriers. Unless they're "enhanced" and have steel that completely covers the firing pin. This is a big weak spot and your bolt carrier cracked right in this area. They will vary on how much material is removed depending on who made the bcg. I'd guess your bolt carrier had too much steel removed.

Similar to the old Beretta M9 locking block lugs that used to shear off. And the weak spot where the slide cracks. The clones coming out of Turkey are the older M9 design. They don't have the slide stop that prevents it from flying back at you if/when it breaks.

View attachment 1925128 View attachment 1925132

But… it's not cracked.