Broken gas key

Rustydust

Active member
Was out popping groud squirrels with good friend Kevin today. Just installed a new spring and rubber doughnut in my ejector in my AR-15 and wanted to see how it was working. Shot one round off and the report sounded funny. The bolt did not come back so I manually ejected the spent round and tried again. Same thing. Huh. Pulled the bolt out of the gun and noticed that the front half of my gas key (the part the goes up against the gas tube) was broken off. WTH? How did that happen? A few years ago I had the barrel threaded for my HTG suppressor and Kevin seems to think that the suppressor might have caused more blow-back force resulting in the failure of the gas key. Since I am not an AR expert I thought I would toss this one out there and ask you guys. What say you? Did the addition of a can on the end of my barrel cause this or at least help it along? Something I need to do to keep this from happening again?
 
How many rounds are on that bcg? Seems to me that they didn't heat treat or use the right steel. I'd let the outfit know whoever they are that made the bcg, and see what they say. Have you ever dropped it onto a concrete floor that could of stressed it? I'm just trying to figure this one out here. If you had to figure a weak spot, the spot you describe would be the spot I would figure would break since it's the least amount of steel there. If it was from just a can, I would think we would hear more of this with so many guys shooting with a can now. You might want to put an adjustable gas block on it now and see if you can fine tune it anyway. After you get a new key of course ;•)
 
How many rounds? Heck, I dunno. 2,000 maybe? It is a Model 1 upper and a few years back I had the bolt break in two. Replaced it with one from DPMS and no more issues until this happened. I got me a new key coming from Stag arms so hopefully will never happen again. And you are not the first one to recommend an adjustable gas block. I just wonder how necessary it is and how well they work.

Thanks for the reply. Hope a few more chime in. Love the gun but dont like problems with it. Sure is a shooter I will give you that.
 
The bolt broke in two? Wow. Sounds like you have an over gassed mess on your hands. Have you looked at the alignment? With the gas tube and how the bcg travels back and forth. You have a major issue somewhere. And as far as adjustable gas blocks go that's all I use on my builds now. Very easy to get your brass to eject softer and time everything up with the load you decide on. Most everyone I know that goes to adjustable blocks will only use them now. It used to be you had to spend $100 on a syrac one, well now I've bought them for under $30 each when I bought a handful at a time. Check the diameter of the gas port hole in the barrel when you get a chance. See what the largest diameter drill bit that fits in there is. That will give you a good measurement. Something seems very wrong when things are breaking like you describe.
 
A broken carrier key is a rare occurrence. Was it loose??? Those stupid little cap screws can get loose from the heat and pounding they take. Sounds like you might have just had one that was defective. I would try again with another one and see before you go tricking out the entire rifle for no reason. I install the key with red Locktite and rarely ever stake the screws because I never fire full auto. Many people insist on staking the screws, some even tack weld them. Personally, I have never had them come loose on mine.
A suppressor will cause more crud to be blown back in the action, that is why they developed the gas piston conversion. I have never seen/seriously doubt that the use of a suppressor alone would break the key. As to the adjustable gas block...they do what they are supposed to do, allow the rifle to function with the minimum gas pressure needed. That's a good thing, less wear and violence in the action. It's also a very unnecessary one in the AR platform. Like a lot of things...guys that swear by them do so because they have to justify spending the money. An adjustable gas block is a nifty add on that is completely not needed. Buy one if it makes you happy but don't expect it as a be all end all of anything.
 
OK. First off the bolt broke years before I ever put a suppressor on the gun. It was an known issue with some Model 1 uppers. I understand that issue has been fixed for some time now.

As far as the gas key I suppose that at one time or another over the years I may have indeed dropped the bolt on my concrete floor and weakened the key. But sure do not remember doing it. And as far as the key being loose, no. Just the tip of it broke off. I will red locktite my new one on there anyway. I understand around 50-60 inch pounds is the right torque to tighten them to?

And thanks guys for the advice about the adjustable gas tube. That may be a big help. I will check it out.
 
Originally Posted By: robjacobscan you post some photos of your bcg and gas key for us?


Dunno. Could try. But it really looks like any other BCG to me except about 1/2" of the tip of the gas key is missing. Dont really know what a photo is going to tell you.
 
Yes suppressors can/will increase the cyclic rate and sometimes significantly depending on the suppressor design. This increases stress on the BCG.

Yes adjustable gas blocks work very well to decrease the amount of gas coming back through the action. I would stay away from the set screw designs. The Syrac Ordnance Gen II is what I'm currently using for my builds. There are other good designs.

When you adjust your gas down be sure to not take it right to the edge of the bolt locking open on an empty mag. The reason is temperature changes can change how well the bolt cycles. I adjusted my gas down to the edge in hot weather and had a nasty double feed at an inopportune time when shooting at night.

Find the edge of the gas frontier and give it 3/4 turn back open and you should be good.

Sendit
 
Originally Posted By: msinc... That's a good thing, less wear and violence in the action. It's also a very unnecessary one in the AR platform...

I am confused. Less wear and tear is a good thing? Or a bad thing?

Why is less wear and tear "very unnecessary"? especially in the AR Platform?

Who here sings the praises of adj. gas blocks just to justify their purchase.
Pretty condescending post, but, whatever.
 
Originally Posted By: C.JayOriginally Posted By: msinc... That's a good thing, less wear and violence in the action. It's also a very unnecessary one in the AR platform...

I am confused. Less wear and tear is a good thing? Or a bad thing?

Why is less wear and tear "very unnecessary"? especially in the AR Platform?

Who here sings the praises of adj. gas blocks just to justify their purchase.
Pretty condescending post, but, whatever.

Sorry for the confusion. I am all for less wear and violence in any action but, very simply, the adjustable gas block is unnecessary. If it was needed the Army and Marines, not to mention many others, would certainly have them. How long has the same general design gas system {without an adjustable gas block} been in use???? I haven't heard of any future changes by the people that shoot this design for purposes other than fun. Do you really believe it's a concept the most important users, the ones that stake their lives on it everyday, of this weapon platform just haven't caught onto yet????? Buy one and use it if it makes you feel good. Just about every problem that could possibly be tied to the gas system, however miniscule, gets the same response here..."oh my god, run right out and get an adjustable gas block, that'll fix it!!!!" If there is a malfunction on that weapon there is another problem, not the lack of an adjustable gas block, less wear and tear??? Yeah. Repair a malfunctioning rifle, nope.
 
Originally Posted By: msinc
Sorry for the confusion. I am all for less wear and violence in any action but, very simply, the adjustable gas block is unnecessary. If it was needed the Army and Marines, not to mention many others, would certainly have them. How long has the same general design gas system {without an adjustable gas block} been in use???? If there is a malfunction on that weapon there is another problem, not the lack of an adjustable gas block.

I think that is the best answer yet. I do not use hot loads in my AR and most of the time they are not quite even .223 power equivalent. I think that the small bit more bolt thrust that I may get from using a suppressor is more than likely insignificant.
 
That is correct...the only thing a suppressor will do is dirty up the gas system and make it a pain to clean. This is why the piston driven gas system was developed. But again, the Sionics suppressor developed by Mitchell Werbell during the Vietnam war was used by Special Forces with the same system you have right now and there were no complaints about it causing any problems. It was bigger and from what I have seen more effective than most in use today, so it had to cause probably more back pressure. It was also way heavier than anything currently produced that I am aware of, which no doubt helped the demise of that design.
The best use of an adjustable gas block is if you intend to shoot hot or higher pressure loads. Rather than installing a heavier action spring and picking up bolt speed you can simply dial down the pressure. I don't understand arbitrarily installing one on every gun you build because they are only optimum when adjusted for each different load. If you have to drop back and shoot lower pressure or normal level loads the gun will short stroke. Now, if you are like me and shoot one load all the time...they are not a bad thing by no means. But to install something that is really unnecessary to begin with and have to readjust it every time you switch loads...not me.
 
Originally Posted By: msincsomething that is really unnecessary to begin with

I guess it all depends on your definition of "necessary".

Strictly speaking you are right I suppose -- an adjustable gas block is "unnecessary."

So is any given type of varmint ammunition since 90% of coyotes can be killed just as dead with cheap ammunition given the average range of the called coyote.

So is a silencer to begin with. Foam ear plugs would do you just as well.

So is anything other than a cheap 3x9 scope.

And really, do I NEED those aggressive treads on my tires? Probably not.

What about that electronic call? Do I really need it?

I suppose the AR itself is unnecessary if you want to get picky about it.

It follows then that the adjustable gas block -- a relatively inexpensive item costing the equivalent of about 200 rounds of ammunition depending on what/where/when -- that allows the user to tune the action of their coyote rifle to minimize recoil impulse is, in the end, unnecessary if one takes a strict definition.

But this is what I do. I don't golf. I don't buy nice cars. I don't go out to eat at nice restaurants. I don't go to pro football games or buy pay per view or bowl or boat or ride an unnecessary Harley. I like killing coyotes and I like hearing and seeing the bullet impacts when I do so.

Necessary? Of course not. Part of every build I currently do. Well ya it is.

Sendit

ps - to the OP, I will butt out of your thread at this point. I've never actually met someone who has broken a gas key. msinc is right in his other assertion that you probably have something else fundamentally wrong going on.
 
"Necessary? Of course not. Part of every build I currently do. Well ya it is."

And if I were building Ar's for the people on this forum I would probably have to make it part of mine too...they have heard it so often and they now believe this thing is so important, so needed, that at this point you probably wouldn't be able to sell a rifle without it.

"I guess it all depends on your definition of "necessary"."

No, it really depends on how far you want to go...you can kill a coyote with a rock. You can drive your car with your feet too, but that don't make it a good idea.


 
Originally Posted By: msinc"Necessary? Of course not. Part of every build I currently do. Well ya it is."

And if I were building Ar's for the people on this forum I would probably have to make it part of mine too...they have heard it so often and they now believe this thing is so important, so needed, that at this point you probably wouldn't be able to sell a rifle without it.

"I guess it all depends on your definition of "necessary"."

No, it really depends on how far you want to go...you can kill a coyote with a rock. You can drive your car with your feet too, but that don't make it a good idea.




Just for the record, I do not own an adjustable gas block. I think my issue with your post is it deals in absolutes and is very condescending.

Do you know a fella named mj36639?

If talk of adj. gas blocks gives you such angst, might be time to go out and burn a few rounds, you know, unwind a bit.
 
An adjustable gas block is absolutely necessary on the rifle of rustydusts. It's the only rifle I know of the blew a gas key off and split a bolt in half. Sounds like the gas port they drilled way oversize. So short of a new barrel an adjustable gas block is necessary. The military contract goes to the lowest bid that the contract calls for. So that arguement means nothing. And an adjustable gas block is sometimes necessary if you shoot different calibers and play with different powders and things like that. If you want the action to work properly.
 
I'm there with ya, I think the gas port hole in the barrel was drilled oversized. Which an adjustable gas block would certainly help with unless your wanting to trade a good shooting barrel for a new one. I'm assuming your rifle is carbine length and that to me would mean even more gas to the bcg. I have never heard of anyone having a broken bcg and then a broken gas key.. Does it feel like its cycling hard when you shoot it Rusty?
 
"I think my issue with your post is it deals in absolutes and is very condescending."

In time you will be able to get beyond this {of course you haven't in a week}...maybe it's time for YOU to go blow up a few rounds...first make sure you dial that gas down.

"The military contract goes to the lowest bid that the contract calls for."

Typical civilian B.S., I am sure you know this because you are involved in so many govt contracts...you've been watching too much tv...contrary to popular belief very few military contracts are "lowest bidder" most are "best value" or IDIQ. I'll let you figure that one out.

"I'm there with ya, I think the gas port hole in the barrel was drilled oversized."

Yeah, because that happens all the time. Wrong bit in a CNC machine???? About as often as the bore itself is the wrong size. Doubt it, but it does make a good sounding excuse to be like everyone else and buy a cure all magic gas block. If you want one just go buy it, you dont have to make excuses.
 
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