View Full Version : Gas tube alignment.
sinlessorrow
03-05-12, 21:39
hello, I recently got a DD MK18 upper and I finally got it to the range the other day.
I put 360 rounds through it(180 M855, 180 wolf) it ran great and gave me no troubles. when I got home to clean it to remove all the packing grease that had melted from the heat I noticed something that I'm not sure if I should worry about.
When you remove the BC the gas tube makes this very slight clinking noise, I found out that the gas tube move slightly back into place against the upper receiver(at the gas tube hole in the front) when it leaves the carrier key. This makes a slight clink noise from the gas tube hitting the upper.
There does not seem to be any excessive tension when inserting just the BC and it seems to go into battery very easily, but knowing that the gas tube slightly moves to get into the Key should I be worried?
I asked another place and was given the advice to just bend the gas tube in the upper which I am thinking of doing but I want to get some advice from the professionals here.
I am not certain about any "clicking noises." I would look to see if there is any wear on the tip of the gas tube. Also, look down the barrel to see how the gas block is sitting inside the rail? Too much to one side or the other?
C4
sinlessorrow
03-05-12, 22:25
I am not certain about any "clicking noises." I would look to see if there is any wear on the tip of the gas tube. Also, look down the barrel to see how the gas block is sitting inside the rail? Too much to one side or the other?
C4
Gas block is about as perfect as they come.
It's honestly difficult to really accurately describe, but when the carrier key starts to interface with the gas tube you can see it slightly move up, and when I say slightly I mean less than 1mm. Now when you go to take the carrier out and the gas tube leaves the carrier key it moves down and when it touches the bottom of the gas tube hole in the upper it makes a little noise.
gas block alignment
http://i203.photobucket.com/albums/aa273/SinlesSorrow/Mobile%20Uploads/IMG_0156.jpg
best I can get of gas tube but doesnt appear to be any excessive wear after 360 rounds
http://i203.photobucket.com/albums/aa273/SinlesSorrow/Mobile%20Uploads/IMG_5064.jpg
Heavy Metal
03-05-12, 22:42
Gas block is about as perfect as they come.
It's honestly difficult to really accurately describe, but when the carrier key starts to interface with the gas tube you can see it slightly move up, and when I say slightly I mean less than 1mm. Now when you go to take the carrier out and the gas tube leaves the carrier key it moves down and when it touches the bottom of the gas tube hole in the upper it makes a little noise.
gas block alignment
http://i203.photobucket.com/albums/aa273/SinlesSorrow/Mobile%20Uploads/IMG_0156.jpg
best I can get of gas tube but doesnt appear to be any excessive wear after 360 rounds
http://i203.photobucket.com/albums/aa273/SinlesSorrow/Mobile%20Uploads/IMG_5064.jpg
When I tweak a gas tube, I strip the carrier and remove the CH. Lube the BC and tweak it till it easily swallows the gas tube as a slhallow angle UPSIDE DOWN. I tweak it by bending it under the handguard. This is hard with an installed rail and needs to be done first. I am trying to get it to swallow the tuble with as little defelction and contact as possible.
leadsender
03-05-12, 22:51
My Noveske upper has the same symptoms I removed the rail to look to see the gas tube better and didn't see anything out of place. My best reasoning is that the gas tube maybe rotated on me somehow because it wasn't doing it the last time I cleaned it and 500 rounds later I have that click when the gas tube clears the gas key. I'm not to worried about it there is no wear on the gas tube and I have 1400 rounds through my upper.
The method shown HERE (http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES) is how I have tweaked my gas tube when I built an upper. I had to tweak the end of the gas tube since the rail was covering the main body of the tube. I think this is what Heavy Metal was referring to as well...
sinlessorrow
03-05-12, 23:21
The method shown HERE (http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES) is how I have tweaked my gas tube when I built an upper. I had to tweak the end of the gas tube since the rail was covering the main body of the tube. I think this is what Heavy Metal was referring to as well...
what did you use to get the pressure needed to tweak it? ive tried by finger and i just cant get enough pressure
Heres an excellent guide on WEVO that shows some ways to adjust gas tube alignment among other things.
http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES
sinlessorrow
03-05-12, 23:45
Heres an excellent guide on WEVO that shows some ways to adjust gas tube alignment among other things.
http://www.weaponevolution.com/forum/showthread.php?1613-FAQ-s-BASIC-INSPECTIONS-AND-PROCEDURES
going by step 3 my gas tube seems to be within tolerances. the BC easily went in under its own weight
justin_247
03-06-12, 04:22
I put 360 rounds through it(180 M855, 180 wolf) it ran great and gave me no troubles.
...
There does not seem to be any excessive tension when inserting just the BC and it seems to go into battery very easily, but knowing that the gas tube slightly moves to get into the Key should I be worried?
If it ain't broke, don't fix it.
going by step 3 my gas tube seems to be within tolerances. the BC easily went in under its own weight
then I wouldnt worry too much ;)
maybe the clinck sound comes from something else..
I think you're fine personally. Just shoot and monitor.
If it is shooting without any issues then I would say your are GTG. I haven't ever noticed any of my rifles making a noise but next time I take mine apart I'm going to listen closer to see if mine does it.
sinlessorrow
03-06-12, 09:03
If it is shooting without any issues then I would say your are GTG. I haven't ever noticed any of my rifles making a noise but next time I take mine apart I'm going to listen closer to see if mine does it.
Thanks for checking, and thanks for all the help. I'll just shoot the heck out of it and keep an eye on the gas tube
Heavy Metal
03-06-12, 09:27
going by step 3 my gas tube seems to be within tolerances. the BC easily went in under its own weight
I like to do step three at as shallow an angle as possible.
jonconsiglio
03-06-12, 09:47
As long as it's not impacting the front of the gas key when it moves forward, I wouldn't worry about it. If you do decide to bend it a bit, you can remove the entire RIS II and only have the mounting ring. That way you have a lot more to work with.
sinlessorrow
03-06-12, 09:49
As long as it's not impacting the front of the gas key when it moves forward, I wouldn't worry about it. If you do decide to bend it a bit, you can remove the entire RIS II and only have the mounting ring. That way you have a lot more to work with.
It is not impactin the front basically the ramped part of the carrier key contacts the ramped part of the gas tube and guides it in place.
Mark82ndABN
03-06-12, 10:44
I just picked up my DDM4V3 last week and mine was doing the same thing. Actually mine did not pass the carrier only "slide test". I tweaked the gas tube and it passes now but you can still hear a slight "ticking" but I'm not worried about it. I think they are pushing these things out the door too fast because of the demand. They need to slow down a bit. Upon receiving my DD I looked it over and found a few issues. The rear take down pin could not be fully pushed in to the point the detent engaged. I had to carefully file the head of the push pin that was hitting the detent channel in the lower so it could fully seat.... no big deal I guess. The second thing I noticed was a bur where the gas key meets the carrier. This bur caused a scrape along the inside of the upper from when they test fired it at the factory. I removed the bur easily and the scrape inside the upper won't effect function but damn. Again, none of this effects function which is why I did not contact DD but all of this doesn't leave me with a warm fuzzy feeling with my first DD.
sinlessorrow
03-06-12, 11:55
I just picked up my DDM4V3 last week and mine was doing the same thing. Actually mine did not pass the carrier only "slide test". I tweaked the gas tube and it passes now but you can still hear a slight "ticking" but I'm not worried about it. I think they are pushing these things out the door too fast because of the demand. They need to slow down a bit. Upon receiving my DD I looked it over and found a few issues. The rear take down pin could not be fully pushed in to the point the detent engaged. I had to carefully file the head of the push pin that was hitting the detent channel in the lower so it could fully seat.... no big deal I guess. The second thing I noticed was a bur where the gas key meets the carrier. This bur caused a scrape along the inside of the upper from when they test fired it at the factory. I removed the bur easily and the scrape inside the upper won't effect function but damn. Again, none of this effects function which is why I did not contact DD but all of this doesn't leave me with a warm fuzzy feeling with my first DD.
Thanks for your input and I hate to hear the extra work you had to do but at least I the ticking(great description btw) seems to happen with others
Heavy Metal
03-06-12, 12:27
Remember to tweak it to where the carrier clides over with the upper UPSIDE DOWN. The carrier is constantly pushed to the top of the reciever by the cartridge column in the magazine.
sinlessorrow
03-06-12, 12:33
Remember to tweak it to where the carrier clides over with the upper UPSIDE DOWN. The carrier is constantly pushed to the top of the reciever by the cartridge column in the magazine.
Ill have to remember that, thanks. When I ge off work ill play with it some more.
I'm gonna see if I have a flat head screw driver that I can use a a lever to tweak the gas tube, if I'm thinking coreectly it should work
I used a piece of paracord to tweak the gas tube downward (loop it around the gas tube and pull). A screwdriver or anyhing else that fits can be used to tweak to the sides or upward.
sinlessorrow
03-06-12, 12:49
I used a piece of paracord to tweak the gas tube downward (loop it around the gas tube and pull). A screwdriver or anyhing else that fits can be used to tweak to the sides or upward.
I think i have a small enough flat head to fit in the reciever, do i just put the tip on the tube and push? I need to tweak it up.
Yes. And if you're worried about marring anything up, then you could use just about anything to do that. Even a ball point pen with the point retracted might work.
Glad to see my tutorials are helping folks out.
These little details, like gas tube alignment, are often over looked during assembly.
Who knows- those couple extra minutes following these often overlooked procedures (originally taken from the -23) might save you some troubleshooting and/or early gastube replacement down the road.
The difference between something good and something great is attention to detail.
sinlessorrow
03-06-12, 13:28
Glad to see my tutorials are helping folks out.
These little details, like gas tube alignment, are often over looked during assembly.
Who knows- those couple extra minutes following these often overlooked procedures (originally taken from the -23) might save you some troubleshooting and/or early gastube replacement down the road.
That was an excellent write up Quib. The gas tube alignment is something I have never thought to check.
Hey Quib since you wrote it what would you recommend for tweaking to tube in the receiver? My upper has a Ris ii on it that im tryig to avoid taking off since i have everythig zero'd
Like you mentioned my fear would be excellersted wear leading to a replacemt early on the gas tube
Heavy Metal
03-06-12, 13:29
I use a large, wide flat blead screwdriver witth the tip heavily wrapped in electrical tape as a tool for this.
sinlessorrow
03-06-12, 13:55
I use a large, wide flat blead screwdriver witth the tip heavily wrapped in electrical tape as a tool for this.
Excellet i never thought of wrapping the tip, I have a ton of duck tape.
I will report back later with my results
Glad to see my tutorials are helping folks out.
These little details, like gas tube alignment, are often over looked during assembly.
Who knows- those couple extra minutes following these often overlooked procedures (originally taken from the -23) might save you some troubleshooting and/or early gastube replacement down the road.
Yes sir. I sat and read each one, good job.
sinlessorrow
03-06-12, 16:56
alright got done tweaking it a very tiny amount and the noise is still there but its alot better than it was, I'm confident that the tiny bit its still off wont make any difference.
I appreciate all the help.
I don't think you can get rid of the noise of the gas tube engaging the carrier key and that's not the goal here.
The important thing here, is when performing the test, that the carrier key does not hang-up on the gas tube, but ramps up smoothly into position.
If the carrier stalls on the gas tube as the receiver is tipped up, or the carrier physically shoves the gas tube to one side or another while sliding into position, then I feel some tweaking is in order.
sinlessorrow
03-06-12, 17:48
I don't think you can get rid of the noise of the gas tube engaging the carrier key and that's not the goal here.
The important thing here, is when performing the test, that the carrier key does not hang-up on the gas tube, but ramps up smoothly into position.
If the carrier stalls on the gas tube as the receiver is tipped up, or the carrier physically shoves the gas tube to one side or another while sliding into position, then I feel some tweaking is in order.
Good to know Quib, I did tweak it a little and it does seem to be a bit smoother.
Mark82ndABN
03-06-12, 18:26
I don't think you can get rid of the noise of the gas tube engaging the carrier key and that's not the goal here.
The important thing here, is when performing the test, that the carrier key does not hang-up on the gas tube, but ramps up smoothly into position.
If the carrier stalls on the gas tube as the receiver is tipped up, or the carrier physically shoves the gas tube to one side or another while sliding into position, then I feel some tweaking is in order.
Quib,
In my previous post in this thread I should have mentioned that in my search for info to solve my gas tube alignment problem it was your post I used to correct my issue. Thanks for your input!
Quib,
In my previous post in this thread I should have mentioned that in my search for info to solve my gas tube alignment problem it was your post I used to correct my issue. Thanks for your input!
No problem Mark. Glad my info helped and thanks for your service to our country. -Quib
Heavy Metal
03-06-12, 19:10
When the handguards can be removed, I FEEL the tube deflection by holding it very lightly between my thumb and forefinger as the carrier slides. I strive to minimize this.
Are you losing pressure (gas)? Not enough to cycle the bcg fully? Dents in the gas tube? Failure to go into battery? Deformation of the gas tube? Movement to the point of bending the gas tube to where it will not come back into alignment?
If not just shoot the weapon, and keep a CLOSE eye on the gas tube end. Time is a great storyteller. Had the same problem only once and this was the advice of an old man whom I respect. Keep us posted.
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