View Full Version : Enhanced/Heavy Duty Gas Tubes
Straight Shooter
01-05-12, 08:52
Strictly for informational purposes only-
Ive been wondering about these. After watching the Colt video where they shoot those several hundred rounds on full auto, the thing that failed was the gas tube. Then, I see a video with an "enanced tube".
Who makes these? On a SHTF type rifle, would this be a worthwhile addition or not at all needed?
What about melonite coated tubes? Any advantages or disadvantages?
Again, only wondering about these. No way I could ever fire the amount of ammo it took to melt that tube.
Also-a search here rendered nothing on this.
Where can the video you are referring to be found?
Straight Shooter
01-05-12, 09:00
Go to youtube and type in something like M4torture test, or something like that.
They dumped, IIRC, 900+ rounds full auto as fast as they could insert mags, in one vid the barrel warps. Very cool.
On a SHTF rifle or any other rifle probably not worth the time or money.
A.) You don't have a full auto rifle
B.) You probably wouldn't be carrying that much ammo in a SHTF situation
C.) I don't think your concern is grounded in reality
The only "enhanced" tube I'd even bother trying would be the Fatboy from PRI is I had an overgassed carbine either due to gas port size or use of a suppressor.
Interesting I'd like to know myself
Straight Shooter
01-05-12, 09:09
AGAIN...please understand me.
Im ONLY WONDERING about this. NOT concerned or worried in the least.
Just wanting technical knowledge, more info, is all.:meeting:
AGAIN...please understand me.
Im ONLY WONDERING about this. NOT concerned or worried in the least.
Just wanting technical knowledge, more info, is all.:meeting:
Fact! It's great to be informed
I do unique testing. The small time it takes to change a 30 rd. mag saves the gas tube. There are mil plots I don't have linked to directly that show the up and down nature.
A gas tube melt point is a function of how many rounds fired how fast. It also depends on ammo and porting.
For example here is me with a total melt down of a mil spec gas tube in 400 rds of Wolf..
http://www.youtube.com/watch?v=sPhbO208I2U
We made some gas tubes that don't fail, ever. Inconel and oversized. Then we reduced the oversized went to standard gas tube size with inconel. The inconel isn't cheap, stainless gas tubes are cheap as hell. In the end you just really need a support for the gas tube about 1 inch behind the port from the underneath and you'd go much further. They get hot and droop but are still holding pressure. Its a little bit of a fuse for the system but I would have thought it had been upgraded a long time ago just because of the possibility.
I melt tubes all the time, I use the lightest profile barrels and I have never had a rupture so I believe there is a huge amount of difference between barrel rupture and the point of the tube failing but it is largely dependent on the modes of fire. I think things should be tested in the worst case scenario.
This isn't the time for the piston hoora because I have popped op-rods, blown regulators out the front. A good piston gun only helps you when you are at the temperatures you should be way more aware of cook-off....
http://www.youtube.com/watch?feature=player_detailpage&v=XVr3lDlH6NY#t=270s
Melonite, Nickel Boron, hard chrome etc... any of these coatings can only make a good product better. I'd have no problem using a gas tube or any other quality made part that was coated in any of these. The AR industry, like many others continues to evolve. As completely new innovations seem to be lacking, coating rifle components is the newest addition. It won't make up for poor maintenance, but might make the time to failure last a little longer. Last I saw, a Spikes Melonite coated gas tube cost damn near the same as a standard Stainless one. If I was doing a new build, I'd use it in a heartbeat.
Straight Shooter
01-05-12, 11:31
Good answers gents..thanks for the info and the links.
Keep em coming!
I forgot to mention that all gas tubes are not equal. Some commercial tubes are really weak to temps. So go spec. The alloy variances in the stainless change the amount of Nickel. Lots of Nickel in Inconel.
I don't really see how a coating is going to help a tube unless it is a hard coating that helps rigidity through the temp cycle.
The nickel content should prevent any corrosion in the standard tube.
I have also blown tubes, they will blow a hole in them at the same area where they tend to melt. So the high temp cycling makes the parts weaker. The tubes that have blown never reached melting temp, that's why they got to be cycled through the temp variations so many times. You almost have to get a new sight base because getting that little chunk of tube out is about impossible if its stuck.
Melonite, Nickel Boron, hard chrome etc... any of these coatings can only make a good product better. I'd have no problem using a gas tube or any other quality made part that was coated in any of these. The AR industry, like many others continues to evolve. As completely new innovations seem to be lacking, coating rifle components is the newest addition. It won't make up for poor maintenance, but might make the time to failure last a little longer. Last I saw, a Spikes Melonite coated gas tube cost damn near the same as a standard Stainless one. If I was doing a new build, I'd use it in a heartbeat.
IIRC, the Melonite tubes originated on their 5.45 uppers for use with corrosive ammo. Beyond that, their use strikes me as nothing more than marketing hype. Anything with a special coating has to be better, right? I have my doubts about any coating being able to improve durability under such harsh conditions, but would be interested in seeing some test results.
Straight Shooter
01-05-12, 15:20
Thanks for the replys.
Armatec- I had to look up Inconel...Id never even heard of it before. After reading about it...wow...very strong stuff it sounds like.
You say youve made gas tubes from this before?
Are you in a firearms/gunsmith type job?
How much would an Inconel gas tube cost?
Thanks for the vids, man yall damn sure put some rounds downrange.
Also-what IS the industry spec for gas tubes? Ive never seen it before, come to think of it.
inconel is actually a trademark name for a particular manufacturers material, the material is nearly identical to a few others but everyone I have ever known uses the inconel.
Inconel is the go to in firearms industry for ultimate material with heat and strength, but you have to come correct with your machining setup rigidity, and feeds,speeds. Gummy stuff, knights makes a break out of I think.
I am an engineer at Armatac Industries.
We have made them, like I said. I got good information from Colt Canada on how they handle their LSW, they have a straight tube that is thicker. So you can use a thicker stainless tube and really make it hold up to high temps. You have to turn down the ends. Thicker tubes don't fit all the handguard situations though.
like anything, you learn how important every feature is on the tube by trying different things. I was doing an experiment and ruined one inconel tube but learned that you can remove a very small fraction from the od of the tube sticking in the gas key and retard the overgassing from being overported(another goofup)
Straight Shooter
01-05-12, 17:19
What would the Inconel tube cost?
Do you/did you ever sell these to the public?
Besides Inconel, any other materials you might recommend for a "enhanced" tube?
Many thanks for your posts, sir.
Where can the video you are referring to be found?
http://video.nytimes.com/video/2010/01/12/world/asia/1247466496261/m-4a1-firing-test.html
I forgot to mention that all gas tubes are not equal.
No truer words spoken, I used to go round and round online with this subject back in the "parts is parts" days. I knew this firsthand from a lot of full auto with M16s then later on with commercial full autos.
johnpuga1982
01-05-12, 21:17
Where can the video you are referring to be found?
http://youtu.be/Kzfm4pYhIyY
johnpuga1982
01-05-12, 21:27
For example here is me with a total melt down of a mil spec gas tube in 400 rds of Wolf..
http://www.youtube.com/watch?v=sPhbO208I2U
What's up with that fire down range?
On a SHTF rifle or any other rifle probably not worth the time or money.
A.) You don't have a full auto rifle
B.) You probably wouldn't be carrying that much ammo in a SHTF situation
C.) I don't think your concern is grounded in reality
The only "enhanced" tube I'd even bother trying would be the Fatboy from PRI is I had an overgassed carbine either due to gas port size or use of a suppressor.
I tend to agree with this.
Seems like a gimmick to me.
Take a look at the Colt/Diemaco LMG (modified M-16). It used a gas tube with thicker tube walls for sustained full auto fire. It also used a hydraulic buffer lower the cyclic rate.
You mean this...
http://img846.imageshack.us/img846/1517/imag0274rl.jpg
http://img703.imageshack.us/img703/9764/imag0273tf.jpg
This is a standard inside diameter but .25 od straight tube, the same as the current LSW tube. I think the weak spring and heavy buffer was not the greatest components to add to the system but when it had the open bolt it was probably done to minimize the beating on the hammer that held the bolt carrier to the rear as the open bolt machine gun.
So this is standard stainless tubing turned down on the ends. The inconel is only needed if you need to keep the tube the current size. If you have the room you just go with oversized stainless. Note..the LMG upper also supports the gas tube where the handle is to prevent from drooping. I swear you can probably extend the life of a tube a significant amount if it were not stressed by its own weight and movement when red hot.
I have the specs on this tube on my old computer. If you're doing a tube for the AR you need to make a little bending jig with pins where the bends would be, be careful to not pinch at the bends. Make sure you get the end going into the carrier just like the standard to within .0005" of od on the head.
It's odd that the AR has rings on the bolt body, not on the small tip, and ofcourse it would be hard to have a ring on the tube. If these would have been incorporated dimensional tolerances could be much more lose and performance would be less determined on the tolerances of the output product. Its actjually amazing we have been able to nail all the manufacturing steps necessary.
What is the life of a gas tube?
How much would go into the development of this part as opposed to just buying a new one for .... almost nothing?
I would be concerned about shifting the failure point to something that would be more expensive to repair, and has a greater risk of causing bodily harm when it fails.
TacMedic556
01-11-12, 16:11
Where can the video you are referring to be found?
Videos in article: http://atwar.blogs.nytimes.com/2010/01/12/m4-and-m4a1-guns/
Great article on COLT M4: http://atwar.blogs.nytimes.com/2010/01/08/the-making-of-the-militarys-standard-arms/
Another article: http://atwar.blogs.nytimes.com/2010/07/07/examining-the-complaints-about-american-rifle-reliability/
TacMedic556
01-11-12, 16:14
Couple points that are relevant:
Marines carry what 210 rounds (7 mags) in a loadout? It took far more than that to make it fail.
Perhaps no person would ever be in a situation where they fired this many rounds, and able to reload this quickly.
Shooting an M4 in combat, in schools, at range and for fun, the gas tube will not fail for a long, long time.
The fires downrange were from the other weapons at knob creek.
The failure point is what it is, my point is education, it isn't a particular round count. Did you see how long I actually took between mag changes? I can nuke them lots faster. The point I was trying to make was that it is dependent on the firing discipline. The video showing the Colt test is not a measure of the amount of rounds it takes to kill a tube, do you see the amount of time it is taking for the magazine change. Well if you are faster or slower than that guy then your failure point is different. This is the most true thing I have ever said.
So you trained real hard and you're a ninja mag changer, well given the same firing rate as your buddy because of the time difference you have a different gas tube failure point and cook-off point.
If you have a weapon that is to be used in an environment where there is a possibility of someone totally dogging out the weapon to survive, they are going to do things that are different than your average range day. There have not been reported issues of tubes failing causing problems. I have seen some questionable reports about failing M4 in heavy combat that are plagued with interesting data and wonder if the failure modes were ever attributed to gas tube failures.
of all my torture I think in the end the gas tube is pretty good the way it is, if you have full auto I would look at something that would provide a small help. That is why I suggested the support like seen on LSW. A stupid little block about 1/4" tall of whatever would support the underside of the tube during glowing sagging and isn't that revolutionary. The defense of it being a "fuse" for the system I just don't get because when it goes down it goes down, there is no quick fuse change to get it back into action. Also, I mentioned I had tubes bust just after repeat thermal cycles.
http://img513.imageshack.us/img513/4113/tube001.jpg
here is a pic of some of the tubes that were made, I had a pic somewhere of all the tube failures, generally they look the same with the same sag point.
NVM question answered previously
You mean this...
Yes, that is the one I was referring to.
I am building an lmg upper for my surefire 100rd mags.
I was interested in a heavier gas tube but it probably isn't a real issue for me.
More like I would grab one if I had a chance.
sinlessorrow
11-18-12, 19:30
There was a video that is now not available to see.
It was from Surefire testing out their 100round mags, they had a gas tube from Colt's IAR(standard material, much much larger) they put 5 of their 100 round mags through the M4 without letting it cool and the gas tube was only red.
The tube showed no signs of sagging, it was a pretty cool video but its been removed.
What I will say is the gas tube bursting generally should not be an issue. If you are dumping mag after mag after mag you probably are not hitting much of anything and just making noise.
When the gas tube is glowing red, the metal is in it's plastic state and the tube will be sagging
sinlessorrow
11-18-12, 23:30
When the gas tube is glowing red, the metal is in it's plastic state and the tube will be sagging
I wish the video was still available to better display what I am trying to say about the tube in the video.
I knew the tube was straight for the iar but didn't know if it was thicker or a different alloy, either way because of the heat sink it can handle extended firing schedules better than the M4, once you're that hot different things can happen, like unburned propellants will sometimes fireball the size of your head at your ejection port and its kind of seizure inducing.
nineteenkilo
11-19-12, 16:07
To actually qualify this, there would have to be MTBF testing under extremely rigid conditions to validate any sort of gas-tube-lifespan questions. Under actual scenarios, I suspect they will be infinite or statistically insignificant failures.
Beyond that, the only failures I see in any of this are taking place in fantasy scenarios. I'm not saying it may not have some practical application in an M4. I just can't see it.
Anyone engaging at the rates of fire portrayed here is an asshole. Period. If anyone in my unit had ever done that sort of stupid shit on a two way range, the results wouldn't have been favorable.
The rules are simple. Acquire your target, engage as necessary, repeat.
Anything else is suppressing fire.
No one is capable, IMO, of melting a gas tube with USGI mags in a combat theater. You simply couldn't carry enough ammo or realistically engage targets quickly enough for it to happen. There is a reason that units have 240's and SAWs. Their overbuilt gas tube/regulator/cylinder designs are intended (though rarely ever used) at this rate of fire and can support it. I have personally melted throwaway barrels on both, one right after the other, without any gas issues.
Having said that, thanks for sharing the videos and showing that it is possible and that it may be a potential weakness later down the road. Knowledge is good.
http://www.youtube.com/watch?feature=player_detailpage&v=saj5GOdMPNk#t=171s
great example of about 100 to 150 rounds before a tube failure,
this tube was subjected to many extreme cycles as Jeff is very hard on equipment. This looks more like a blowout than a pure melt.
http://www.youtube.com/watch?feature=player_detailpage&v=saj5GOdMPNk#t=171s
great example of about 100 to 150 rounds before a tube failure,
this tube was subjected to many extreme cycles as Jeff is very hard on equipment. This looks more like a blowout than a pure melt.
Necrothread. Would a pencil barrel have any effect on the lifespan of a gas tube since they heat up and cool down faster? I bought a V Sevens inconel gas tube to go with my Faxon 16" pencil barrel, on a whim, thinking it would shorten the lifespan of a regular gas tube.
I was originally only shopping for a titanium buffer retainer, due to a broken one, but needed as gas tube anyways.
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