Here's something you don't see everyday - AR related

Gardner

Gardner

Let us Fo
Supporting Member
Joined
Dec 25, 2016
Messages
669
Location
MecCo
Rating - 100%
12   0   0
We went to the range today and one of the rifles we took was an AR-15. I assembled this particular AR in 2012.

We had shot several rifles, and I bring the AR to the table, load a mag, insert mag and pull back on the charging handle to chamber the first round. The CH came to the rear an inch or so and stopped. I saw the ejection port door didn’t open so my first thought was the EP door was jammed. No amount of tugging/jerking could move the BCG more than an inch or so.

I finally decided to separate upper and lower. When I did something fell out of the upper. At first I didn’t recognize it but then it dawned on me…...that’s the gas key!!

As you will see in the photos, both screws sheared flush with the BC.

That’s certainly a first for me. But not really, this same BC sheared the front screw when I first bought it. It took forever for me to figure out where the gas leak was.

What’s odd is that before every range trip (the afternoon before) I remove the bolt and check for lube, whether it’s a bolt gun or semi, run a dry patch down the bore and do an overall look see for safety.

The gas key was attached to the BC when I assembled it and put in its case.

To be clear I did NOT fire a single round today before I found this failure.

Luckily I had a spare BCG in the tool box.

Now I have to find a smith to remove the broken screw stubs, I don’ have to tools for the job.

IMG_4291.JPG

IMG_4294.JPG

IMG_4296.JPG
 
Last edited:
I’d contact Young and see what they say. The “leak” has caused some visible erosion so there is a pretty good indication something ain’t quite fitted right. Maybe the surfaces between the key and carrier are not flat fitting and there is something going on there. If it causes a failure in the rear gas key screw forces on the front screw could cause it to fail also … just thinking out loud.
 
Last edited:
Problem is that Mr Young did not believe it was necessary to stake gas keys. Proper torque was sufficient. This was staked by a second party seller and back in the day I believe that Young said that staking a gas key voided the warranty

In any case, not something I want to get into
 
Last edited:
Gardner said:
Problem is that Mr Young did not believe it was necessary to stake gas keys. Proper torque was sufficient. This was staked by a second party seller and back in the day I believe that Young said that staking a gas key voided the warranty

In any case, not something I want to get into
Click to expand...
Uhmn, I am by no means an AR expert but that seems like a pretty wild statement?
 
Gardner said:
I believe that Young said that staking a gas key voided the warranty

In any case, not something I want to get into
Click to expand...
According to their website, you are correct. With the erosion on the key and carrier, I would trash it and move on.
 
Replace the screws and key and rock on.
It looks clear that one screw has been broken longer than the other. Almost like he said. Someone that stakes it used the same screws or broke the screw when staked.
 
Ahhh Young Manufacturing. I remember they were quite popular back in 2012, I had a YM NM in a high dollar build back then. I believe Rainier Arms was the big seller who staked them and yes that voided the warranty. It can’t hurt to ask YM if they’ll help since this carrier has sheared screws twice.

Unfortunately, I doubt it’s worth paying someone to remove the screws. With so many BCG options around $100, I’d buy a new one, not YM.
 
Last edited:
Timfoilhat said:
Looks like trash to me. Not worth the labor charges for someone else or the effort yourself to fix. Time to buy a new one.
Click to expand...

As I said I had a spare, so no need to buy a new one

As for repair, auto techs remove broken studs and bolts all the time. It ain't rocket surgery. If I had a drill press I could do it.

As it is, I'll try to find someone to extract the broken screws
 
Last edited:
Mr.Gadget said:
Replace the screws and key and rock on.
It looks clear that one screw has been broken longer than the other. Almost like he said. Someone that stakes it used the same screws or broke the screw when staked.
Click to expand...

That seems reasonable, but many years and many rounds have been shot since the last replacement.

I'm more inclined to think the mating surface between the key and carrier isn't perfectly perfectly flat. If that were the case, the flex would eventually weaken the screw and they would break.
 
MacEntyre said:
Perhaps, but the explanation makes a lot of sense.
Click to expand...
Not really, though. It makes a case for torque being important, and gives no discussion as to why staking the heads would then void a warranty. Both of those are independent of slathering schmoo under the key.
 
Gardner said:
As I said I had a spare, so no need to buy a new one

As for repair, auto techs remove broken studs and bolts all the time. It ain't rocket surgery. If I had a drill press I could do it.

As it is, I'll try to find someone to extract the broken screws
Click to expand...
True not rocket surgery. But they are hardened screws which will make it a little more difficult to drill and tap with an extractor. With the added kicker of thread locker, an inexperienced person may struggle getting them out and damage the threads.

Edited: I would also be very concerned over the amount of erosion on the bolt carrier, even with a brand new gas key. I don’t know how you will be able to get the carrier back completely flat and smooth so there is no gas escaping.
 
Last edited:
Average Joe said:
Edited: I would also be very concerned over the amount of erosion on the bolt cacarrig.i have seen worse and they run fine.
Click to expand...
Looking at the color of the screws leads one to believe that the front has been broke for some time and the back was the only one holding it. The erosion may not be as bad as it looks.
Only way to tell is to add new screws and key then run it.
Who knows, being it was dicked with the screws may not have any loctite on them.
They may have been soft to begin with. There were a bunch of bad screws out there in the past and many discussions on the quality of the screws.
How many times were they torqued and was the wrench good?

Easy thing is replace the full BCG. That is why I keep 10 or so extras. I also keep the screws and keys if needed. Screws are one time use and trashed.
 
Mr.Gadget said:
Looking at the color of the screws leads one to believe that the front has been broke for some time and the back was the only one holding it. The erosion may not be as bad as it looks.
Only way to tell is to add new screws and key then run it.
Who knows, being it was dicked with the screws may not have any loctite on them.
They may have been soft to begin with. There were a bunch of bad screws out there in the past and many discussions on the quality of the screws.
How many times were they torqued and was the wrench good?

Easy thing is replace the full BCG. That is why I keep 10 or so extras. I also keep the screws and keys if needed. Screws are one time use and trashed.
Click to expand...
Agree about the screws many variables that could have been the point leading to failure. The erosion I’m talking about is on the leading edge of the gas ports. Picture below with areas circled in red. I think putting a new key with new screws will be band aid. But, to repair it and throw it in the range bag to have a spare for short term use would be a good idea.

IMG_8011.jpeg
 
I see that but have also seen it as part of the milling they break that edge with the angle of the gas flow. The key is the same way.
 
I have spares, buy em cheap. stack em deep.

But I like the "bling" of this BCG and I'll try to get it repaired. I paid $175 for it 12 years ago, now they are $275. Unlike I'll throw it away unless it can't be fixed.

I also have the proper screws I bought from BCM years ago, all I need is the stubs extracted.

I also don't see the erosion at the gas hole a factor. I think you'd find that on any BCG.
 
Gardner said:
As I said I had a spare, so no need to buy a new one

As for repair, auto techs remove broken studs and bolts all the time. It ain't rocket surgery. If I had a drill press I could do it.

As it is, I'll try to find someone to extract the broken screws
Click to expand...
Of course there’s a need to buy a new one. You have to replace the spare. The broken one needs to go in the trash. So, one in…one out. 🤔
 
Mr.Gadget said:
View attachment 772270
See how this is done?
Click to expand...
This is one of the many reasons I love this place. Always something to learn. Haven’t seen one like that before.

Edited to add: I’m getting old, heck I could have seen one like that and just don’t remember 🤣
 
Last edited:
"We will not warrantee a carrier with a staked key no matter who staked it. You will be charged for a new key and any labor required to remove broken screws."

It would probably be cheaper to just buy a whole new BCG
 
Supermatch said:
Not really, though. It makes a case for torque being important, and gives no discussion as to why staking the heads would then void a warranty. Both of those are independent of slathering schmoo under the key.
Click to expand...
Young's rationale seems straightforward:
If you do not properly torque the screws to 56 inch pounds you will be staking a screw that is loose or one that is over torqued and prone to breakage.
Click to expand...
and
If you feel the need to stake the screws spend the money and get one of the staking tools from Brownell that uses a screw type system to swedge the material into the top of the screw. Dont use a hammer and a punch! You can stretch the thread on the screw and now you have a loose screw that will eventually break if the gun even fires.
Click to expand...
 
There is a reason Colt BCGs are more sought after than others. It aint the pony, since they don’t have one stamped on them.
Proper metallurgy and staked keys are useful items. If anyone has seen a full-auto bcg without staked-on keys, please advise 🧐
 
Somewhere around here, I have one of the screw/swedge type stakers.

It reminds of aircraft quality standards, where bolts are lock wired to prevent loosening from vibration. ( Don't know if Boeing follows that standard.)

A reciprocating BCG would definitely generate potential bolt loosening vibration. And I believe there are stories of loose keys.
 
Those are grade 8 bolts, loctite breaks down with heat. If you don’t have a drill press available, chuck it in a vice, t hey can be drilled by hand. Use a center punch, a quality bit, keep it wet with oil, and run the drill slow as to not over heat the bit. They’ll come out. My brother’s DPMS AR-10 bolts were staked. They sheared at the first range trip in less than 100 rounds. Replaced the bolts with quality ones, properly torqued & it’s been running for years.
 
Get Off My Lawn said:
Those are grade 8 bolts, loctite breaks down with heat. If you don’t have a drill press available, chuck it in a vice, t hey can be drilled by hand. Use a center punch, a quality bit, keep it wet with oil, and run the drill slow as to not over heat the bit. They’ll come out. My brother’s DPMS AR-10 bolts were staked. They sheared at the first range trip in less than 100 rounds. Replaced the bolts with quality ones, properly torqued & it’s been running for years.
Click to expand...
Here's an aside, but possibly relevant. I was under the impression that grade 8 bolt are strong relative to tightening things, but brittle due to their hardness as they will not bend like a grade 5 might. Is Grade 8 the right bolt for this job?
 
Timfoilhat said:
Here's an aside, but possibly relevant. I was under the impression that grade 8 bolt are strong relative to tightening things, but brittle due to their hardness as they will not bend like a grade 5 might. Is Grade 8 the right bolt for this job?
Click to expand...
Correct, socket head cap screws are typically grade 8. Stronger, but more brittle. So if they loosen a bit, they’ll shear easily. Have you seen car/truck/trailer lugs break off? Usually it’s because they were loose, or Mongo installed them.
 
gc70 said:
Young's rationale seems straightforward:

and
Click to expand...
Again, his first statement has to do with proper torque, which applies regardless of method of securing.

His second statement is nonsense from an engineering perspective. You cannot stretch bolt/screw threads without applying additional torque, which involves rotating the head of the bolt/screw. Deforming a softer gas key material so there is a mechanical interference with the screw to prevent it from rotating, does not generate bolt stretch.

If he prefers Loctite, that's fine, but he shouldn't do so under the guise that staking damages or affects screw torque in any capacity, because its bologna.
 
You must log in or register to reply here.
Back
Top Bottom