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Stickman
04-12-19, 22:58
To say that this thread is overdue is more obscene than most people will know, but aside from me losing parts (hey, I'm honest), I believe in this particular item enough that I think it is worth spreading the word.

The sad news for many people, is that a dirty weapon, and insufficient lube are the primary problems when users experience problems with their weapon. Moving past that we can get into magazine failures and some other common failures, but when we come to actual problems inside the weapon which the user has not managed to bring upon themselves, we find gas problems to be right near the top of the list.

The mechanical failure we see on a regular basis? That one thing that course instructors see over and over while teaching classes? What is one of the first things as a PD Armorer and Firearm Instructor we look for in AR15 POW (privately owned weapons) when teaching courses? The answer is the carrier key screws, and without fail, we almost always find screws that are staked poorly, not staked at all, or have screws that are loose. The last sentence is rather redundant, as poorly staked screws often come loose, screws that aren't staked often come loose, and obviously screws which aren't tight to begin with often come loose. Seems like a simple, yet heinous oversight on the part of Bolt Carrier Group (BCG) manufacturers doesn't it? The simple sad truth is that high quality components cost more money, and if a vendor doesn't spec out top of the line parts, the manufacturer is going to go low quality to meet the bid or price point of the contract.

For some people I might be already speaking tech geek, and yes, this article does assume the reader is somewhat knowledgeable about the AR15/ M16/ M4 and components. I'll back up for a minute and we can look at the need for the carrier key to be locked securely onto the carrier.

A bullet is fired, and from the chamber is propelled down the barrel with great vengeance and fury. Before the bullet leaves the barrel, it passes the gas port, which is of a special size and is covered by a gas block. The pressure of the gases goes up into the gas block, and through the gas tube where it quickly finds itself interacting with the bolt carrier key. Pressure flows through the key and into the body of the BCG, at which point we have lift off!! Not really, but if everything is proper, we do have proper extraction and ejection of the casing, and there has been enough pressure to send the bolt completely to the rear so it can travel forward again as needed. Loose screws cause leaks and the pressure eventually drops to the point of causing malfunctions.

With the above in mind, lets look at the Optimized Carrier Key Screw (OCKS) (http://www.m-guns.com/tools.php) from that mad genius Ned Christiansen at Michiguns as shown below:

https://66.media.tumblr.com/5849fa1ec2935af00b09e983292f4a32/tumblr_ppvm9dt4BL1rrcg2fo1_1280.jpg
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The above screws are not to size.... The OCKS screws are made in the USA, and feature 12 cog, or gear like cutouts. These cutouts give metal from your gas key an area to displace, thereby securing and preventing movement or loosening via mechanical means (staking). Many times AR15 owners hear about the AR15 needing proper "staking", and rush to their weapon to check and see if theirs passes this mystical test. They look at large staking marks, and relax feeling confident they have deep secure staking and have no further need of worry. Sadly, those people have missed the point. When we look at the below carrier and carrier key, on first glance it appears the carrier key was staked heavily, in two opposing places, and that all is well.

https://66.media.tumblr.com/142c93f398520ba0b91e63afbec5114d/tumblr_ppvmayP8fu1rrcg2fo1_1280.jpg
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Now we jump into macro (or micro mode if you are a dirty Nikon shooter) viewing, and see a large problem. The displaced areas on the screw do NOT match the areas on the carrier key! The deepest staking in the world fails if it is not done correctly. Take a look at the below image, and look at the actual screws. There is almost nothing for the displaced metal to lock in place against. There is minimal knurling at best, the top of the screw is almost oval or ridge like meaning the metal would have to travel a massive distance to even make decent contact, and even then still have no way to secure it. You can see this BCG is pretty new as there is almost zero discoloration, and even still, we can see the screws have shifted quite a bit.

https://66.media.tumblr.com/4432272db02c16b8b7712e708d3c68b7/tumblr_ppvmciBOER1rrcg2fo1_1280.jpg
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If after reading all of this, you decide to post online or go check your BCG and compare it to your friends, remember that if you have doubt, it is an incredibly simple fix. Loosen the old screws, and install the new ones. After you are done with that, stake the screws, verify metal has been moved into the little gear cutouts, and you are GTG. Before anyone tells me they can't fasten, secure, stake, or anything else, I'll tell you that it is simplistic. Staking does not need to be pretty, it just needs to be secure. I have used a door jam to prevent the BCG from moving, and then staked carrier keys by using a large flat headed screwdriver and regular hammer. For those people, departments, clubs, or agencies which are looking to do this on a more professional level, there are tools from M-Guns.com which make things look nice and perfect.

I'll close this one up by saying your gun company may have saved a few cents per piece by going the cheap screw route. If you find this to be true, the replacement upgraded screws are 6 for $10, and prices go down if you buy more. This is a quality part, and on a scale of 1-10, it is an easy 10. This is the component which should be on every BCG.

For more information, hit up http://www.m-guns.com/tools.php.


If you have questions, comments, or additional input, please feel free to post it below.

Lastly, if you like this style of article, and may have possibly learned a little tiny bit, please let me know that as well. I try to write (magazine or online) at a level which educates most people, and often with a little humor.

Thanks,

Stick

AKDoug
04-26-19, 11:16
I appreciate you taking the time to write this. I'll likely include this is my next build. Are you aware of any BCG manufacturers using these screws?

1168
04-26-19, 11:20
I appreciate you taking the time to write this. I'll likely include this is my next build. Are you aware of any BCG manufacturers using these screws?

Forward Controls Design

SeriousStudent
04-28-19, 21:13
Very interesting, I appreciate the info and the time you took for the write-up.

Stickman
04-29-19, 21:36
Very interesting, I appreciate the info and the time you took for the write-up.

Thanks, it is one of those small things, at least until a screw snaps or works loose... then its no fun. These really are a better mouse trap.

alx01
04-29-19, 22:26
McMaster sells a US-manufactured Grade 8 fasteners (P/N: 91251A190) for $9.47 per pack of 100.
Realistically speaking what makes OKS worth 10x over a regular trusted and proven screws (60 years worth and millions of BCGs) if they are torqued and staked properly?

Stickman
04-30-19, 19:16
McMaster sells a US-manufactured Grade 8 fasteners (P/N: 91251A190) for $9.47 per pack of 100.
Realistically speaking what makes OKS worth 10x over a regular trusted and proven screws (60 years worth and millions of BCGs) if they are torqued and staked properly?


If that is your takeaway after looking at the above images, and reading the article, there is nothing I can explain that is going to help you understand it. Paragraph 7 pretty much went over that, but you are most certainly free to think what you want.

I can't tell if you are being sarcastic, trolling, or actually don't understand the difference. That is the wonder of the internet, lack of inflection makes it hard to mesh at times.

1168
04-30-19, 19:38
McMaster sells a US-manufactured Grade 8 fasteners (P/N: 91251A190) for $9.47 per pack of 100.
Realistically speaking what makes OKS worth 10x over a regular trusted and proven screws (60 years worth and millions of BCGs) if they are torqued and staked properly?

Stickman: “the replacement upgraded screws are 6 for $10, and prices go down if you buy more.”

$10 for 3 BCGs worth. And less per screw if you have more than 3 BCGs to upgrade. Or you can go to MMC to “build” 50 BCGs for $10 in screws. Do you have 50 BCGs?

These screws may not be strictly necessary, and they may not be for everyone. But if you find yourself fixing a BCG that is getting a bad key seal, or if you are putting a key on a bare carrier, or just want some extra peace of mind, or to have some spares on hand, I can assure you these screws are awesome. I’m hoping they become the new standard. They are part of the reason I have switched to Forward Controls Design SBCG for current and future BCG purchases.

26 Inf
04-30-19, 19:51
McMaster sells a US-manufactured Grade 8 fasteners (P/N: 91251A190) for $9.47 per pack of 100.
Realistically speaking what makes OKS worth 10x over a regular trusted and proven screws (60 years worth and millions of BCGs) if they are torqued and staked properly?

I'd think that folks who have seen a lot of AR's have come across loose carrier keys more often than you or I have.

I ass-u-me that Ned C. saw the need to market these to complement his MOACKs line.

Much like Duffy at Forward Controls Ned C's products seem geared toward flawless function. Seemingly, they are also geared toward the person who is comfortable taking apart their BC and installing, torquing and staking carrier key screws. Not the average shooter/user. The target audience is well aware there are less expensive alternatives.

If you want to be sure, always, get these.

titsonritz
05-01-19, 02:37
Nice write up, thanks for taking the time and posting it here. Yep, the OCKS are definitely the best carrier key screw available on the market. A better "mousetrap" indeed.

For those that missed Ned C's original thread:
https://www.m4carbine.net/showthread.php?195130-On-loose-carrier-key-screws&highlight=carrier

alx01
05-01-19, 17:20
If that is your takeaway after looking at the above images, and reading the article, there is nothing I can explain that is going to help you understand it. Paragraph 7 pretty much went over that, but you are most certainly free to think what you want.

I can't tell if you are being sarcastic, trolling, or actually don't understand the difference. That is the wonder of the internet, lack of inflection makes it hard to mesh at times.

My question is genuine.

My times on this forum and others I have heard that nothing needs to be done if screw is torqued and staked properly.
Some people claim that staking is not even necessary if torque is correct. Not 100% sure of screws needing a Loctite per TDP as I've never run into this problem.

I don't dispute the existence of the issue and in theory Ned's OCKS would make staking stronger.

Your example in the article and Ned's post both allude to two things:
1. Materials: incorrect screws (Chinese made YFS example or similar)
2. Process: incorrect staking and torque

My questions was - if one uses a correct Grade 8 screws (McMaster P/N: 91251A190 or similar) AND the correct process to torque and stake screws would you see a measurable benefit of using OCKS? (which cost 10x of a quality screw)


I don't hear that often about gas key screw failures in Colt, BCM, Daniel Defense, or LMT. I would assume they are using correct materials and processes.

As an example, a person claims to have 100k rounds on BCM BCG without any special screws, treatment or anything else: https://www.ar15.com/forums/industry/BCM_BCG_failure_/138-274255/


From the engineering perspective holding strength of the screw is coming from threads and proper torque is important. Once threads weaken and get stretched/elongated I think no amount of staking will prevent screws from coming loose in BCG application.

I'm not bad-mouthing OCKS as I think the product is actually great. Screws, however, are a commodity item and not a premium product.

I would love to see some measurable comparison between what BCM uses (https://www.bravocompanyusa.com/BCM-Gas-Key-p/bcm%20gas%20key.htm) and OCKS using a correct application, if one exists.

titsonritz
05-07-19, 20:43
I would love to see some measurable comparison between what BCM uses (https://www.bravocompanyusa.com/BCM-Gas-Key-p/bcm%20gas%20key.htm) and OCKS using a correct application, if one exists.


Did you read the original thread Ned started that I linked?

Stickman
05-09-19, 22:48
My questions was - if one uses a correct Grade 8 screws (McMaster P/N: 91251A190 or similar) AND the correct process to torque and stake screws would you see a measurable benefit of using OCKS? (which cost 10x of a quality screw)


From the engineering perspective holding strength of the screw is coming from threads and proper torque is important. Once threads weaken and get stretched/elongated I think no amount of staking will prevent screws from coming loose in BCG application.

I'm not bad-mouthing OCKS as I think the product is actually great. Screws, however, are a commodity item and not a premium product.





Sorry for the late reply, and I appreciate your clarification.

One of the easiest things I can tell you is that most screws I have seen as an instructor, and department armorer, as well as being involved in the weapon industry have been staked. The ones that come loose? They have been staked as well. Why do they come loose? Typically it is because the displaced material has not made solid enough contact with the lightly threaded section on the exterior of the screw head.

If all screws we are talking about are of the same material (giving the benefit of the doubt as per your question), and staked properly, the OCKS would still out perform them. This isn't something that we need science classes for, this is a matter of common sense. When I've seen well staked screws come loose many times, common sense tells me that allowing for material to be displaced deeper into the screw would create a more positive mechanical stop.

I'll happily point out that I have no way to state off the top of my head what the different shear factors would be, and what percentage the gain would be. However, I don't think there is anyone who would think less depth would be as good or better than more depth. The OCKS simply provides allowance for greater depth and holding power (again, that is making the assumption everything else is the same).

Lastly, screws are a commodity item for things that have low relative value. If not, there wouldn't be a milspec (or standard) stating what type of screws should be used. Manufacturers that cheap out on screws and use chinese low quality components, are building a commodity. The ones doing it right are building something different.

I hope this explains it in easy enough terms to understand. I get that not everyone has seem screws come loose to the point where they lock up a weapon, snap heads, create gas problems, or anything else. For a lot of people who only have one gun, are new to the platform, or just haven't seen issues, all of this is probably overthinking something which they really don't care about.

MAUSER202
05-10-19, 20:29
Sorry for the late reply, and I appreciate your clarification.

One of the easiest things I can tell you is that most screws I have seen as an instructor, and department armorer, as well as being involved in the weapon industry have been staked. The ones that come loose? They have been staked as well. Why do they come loose? Typically it is because the displaced material has not made solid enough contact with the lightly threaded section on the exterior of the screw head.

If all screws we are talking about are of the same material (giving the benefit of the doubt as per your question), and staked properly, the OCKS would still out perform them. This isn't something that we need science classes for, this is a matter of common sense. When I've seen well staked screws come loose many times, common sense tells me that allowing for material to be displaced deeper into the screw would create a more positive mechanical stop.

I'll happily point out that I have no way to state off the top of my head what the different shear factors would be, and what percentage the gain would be. However, I don't think there is anyone who would think less depth would be as good or better than more depth. The OCKS simply provides allowance for greater depth and holding power (again, that is making the assumption everything else is the same).

Lastly, screws are a commodity item for things that have low relative value. If not, there wouldn't be a milspec (or standard) stating what type of screws should be used. Manufacturers that cheap out on screws and use chinese low quality components, are building a commodity. The ones doing it right are building something different.

I hope this explains it in easy enough terms to understand. I get that not everyone has seem screws come loose to the point where they lock up a weapon, snap heads, create gas problems, or anything else. For a lot of people who only have one gun, are new to the platform, or just haven't seen issues, all of this is probably overthinking something which they really don't care about.

Cool thread, makes a lot of sense to me for repairs of a loose screw. I think the would hold better on a previously staked key that had a screw come loose. Cheap insurance that it won’t happen again.

alx01
05-11-19, 02:27
Thanks Stick! Great info and examples!

This is a perfect example of how a person with an extensive field experience and exposure can clearly demonstrate some of the lesser known aspects and intricacies. Such information and a long-term evaluation is invaluable from the technical and end-user perspective and demonstrates that even smallest implementation details matter.

Once again, thanks for chiming in and sharing your experience!

Clint
11-14-19, 20:29
BRT is proud to be offering OCKS in our web store as well.

http://www.blackrivertactical.com/concrete5/store/#!/Optimized-Carrier-Key-Screws/p/158785134/category=1852003

We'll likely offer a mil-spec gas key and OCKS combo in the future.

Stickman
12-07-19, 14:08
BRT is proud to be offering OCKS in our web store as well.

http://www.blackrivertactical.com/concrete5/store/#!/Optimized-Carrier-Key-Screws/p/158785134/category=1852003

We'll likely offer a mil-spec gas key and OCKS combo in the future.

That is an awesome offering. its worth having a few of them on hand for guys who shoot a lot, or wrench on weapons.

Straight Shooter
03-29-20, 17:47
Just yesterday got my 20" SPR build back from the smith, as I just posted in another thread. Saw this, and wanted to say, here too, that I had the smith replace the YFS screws in my Young NM bolt carrier, with OCKS I got from Black River Tactical..along with my rifle gas tube, btw. Had him stake it & I consider that matter closed.
BTW-if you SME's ever wonder if anyone listens to your advice- some of us do.