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SC, USA
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Posted: 5/6/2024 10:07:45 PM EDT
I've never seen any instance where this thing even offers the slightest resistance before...
Got a DD MK18 upper, trying to install a BRT gas tube, and the roll pin absolutely will not move. I've put 30 seconds of torch on it, and broken two 1/16" punches.. it won't move a bit. Anyone encountered this before? I'm not even sure how this is physically possible. |
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Posted: 5/6/2024 10:16:58 PM EDT
[#1]
My DD gas tube pin was also crazy tight. I actually bent the first punch trying to get it to move. Wound up breaking that punch at the bend so it was only about 1/2" long and used that with a big hammer. Then used a regular punch once it had broken free to get it all the way out.
And yeah same thing, BRT tube swap. |
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SC, USA
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Posted: 5/6/2024 10:30:43 PM EDT
[#2]
Quote HistoryOriginally Posted By JBecker_72: My DD gas tube pin was also crazy tight. I actually bent the first punch trying to get it to move. Wound up breaking that punch at the bend so it was only about 1/2" long and used that with a big hammer. Then used a regular punch once it had broken free to get it all the way out. And yeah same thing, BRT tube swap. You're the man... used the tip of one of the broken punches with a major whack, and that finally got it started, and then it came right out. Why?  Port in the stock tube has also got to be double the size of the one that BRT sent. Again, why? This is a brand new upper and based on how it shoots, it appears to me they went back to the major overgassing of the pre 2017 timeline from what I understand... anyhow, should be fixed now. Thanks again. |
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Posted: 5/6/2024 10:34:13 PM EDT
[#3]
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SC, USA
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Posted: 5/6/2024 10:39:13 PM EDT
[#4]
Quote HistoryOriginally Posted By xciapup: Not all punches are the same. I already have and love the G tool for getting a new gas tube roll pin installed; so much easier than tweezers and a prayer... I'll definitely add that to my cart for next time they have a sale. |
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Posted: 5/6/2024 10:40:06 PM EDT
[#5]
Quote HistoryOriginally Posted By DVCNick: You're the man... used the tip of one of the broken punches with a major whack, and that finally got it started, and then it came right out. Why? Port in the stock tube has also got to be double the size of the one that BRT sent. Again, why? This is a brand new upper and based on how it shoots, it appears to me they went back to the major overgassing of the pre 2017 timeline from what I understand... anyhow, should be fixed now. Thanks again. Quote HistoryOriginally Posted By DVCNick: Originally Posted By JBecker_72: My DD gas tube pin was also crazy tight. I actually bent the first punch trying to get it to move. Wound up breaking that punch at the bend so it was only about 1/2" long and used that with a big hammer. Then used a regular punch once it had broken free to get it all the way out. And yeah same thing, BRT tube swap. You're the man... used the tip of one of the broken punches with a major whack, and that finally got it started, and then it came right out. Why? Port in the stock tube has also got to be double the size of the one that BRT sent. Again, why? This is a brand new upper and based on how it shoots, it appears to me they went back to the major overgassing of the pre 2017 timeline from what I understand... anyhow, should be fixed now. Thanks again. If I’m understanding what you’re saying correctly, the “port” size in the gas tube itself being large has nothing to do with overgassing. |
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Posted: 5/6/2024 10:42:14 PM EDT
[#6]
Quote HistoryOriginally Posted By WUPHF: If I’m understanding what you’re saying correctly, the “port” size in the gas tube itself being large has nothing to do with overgassing. Quote HistoryOriginally Posted By WUPHF: Originally Posted By DVCNick: Originally Posted By JBecker_72: My DD gas tube pin was also crazy tight. I actually bent the first punch trying to get it to move. Wound up breaking that punch at the bend so it was only about 1/2" long and used that with a big hammer. Then used a regular punch once it had broken free to get it all the way out. And yeah same thing, BRT tube swap. You're the man... used the tip of one of the broken punches with a major whack, and that finally got it started, and then it came right out. Why? Port in the stock tube has also got to be double the size of the one that BRT sent. Again, why? This is a brand new upper and based on how it shoots, it appears to me they went back to the major overgassing of the pre 2017 timeline from what I understand... anyhow, should be fixed now. Thanks again. If I’m understanding what you’re saying correctly, the “port” size in the gas tube itself being large has nothing to do with overgassing. This.^^^ Also to add, current DD 10.3" GP diameter is 0.070", a decrease from the over sized GP diameter of the late 2Ks. |
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SC, USA
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Posted: 5/6/2024 11:16:52 PM EDT
[#7]
Quote HistoryOriginally Posted By WUPHF: If I’m understanding what you’re saying correctly, the “port” size in the gas tube itself being large has nothing to do with overgassing. True, I would expect a DD factory upper to regulate via the barrel port size, which I'm not actually going to measure or even look at right now. All I can tell you for sure is: 1) I had a post 2017 RIS II DD MK18 upper that was strongly, but manageably gassed to where it would function well with a carbine buffer tube/sprinco white (like a stock M4 spring) and H3 buffer with an RC2 on. 2) This brand new production RIS III MK18 upper is WAY overgassed, ejects far forward unsuppressed with anything short of an A5 tube/Sprinco green/A5H4, and still ejects to 2:00 with that setup with an RC2. If BRT did their thing correctly, I should be at or below the total gas level of the first upper; I input unsuppressed with stock everything and an H1 into their spec sheet. So if its good there, I should be able to go to H2/3 with a can and be right where I want to be... will find out soon. |
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Posted: 5/6/2024 11:18:07 PM EDT
[Last Edit: j3_]
[#8]
I'd try the correct size punch.
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Posted: 5/7/2024 5:16:38 AM EDT
[#9]
Quote HistoryOriginally Posted By DVCNick: True, I would expect a DD factory upper to regulate via the barrel port size, which I'm not actually going to measure or even look at right now. As with any factory upper, the barrel GP diameter is the determining factor with system gassing. |
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Posted: 5/7/2024 7:15:47 AM EDT
[Last Edit: JBecker_72]
[#10]
Quote HistoryOriginally Posted By DVCNick: You're the man... used the tip of one of the broken punches with a major whack, and that finally got it started, and then it came right out. Why? Port in the stock tube has also got to be double the size of the one that BRT sent. Again, why? This is a brand new upper and based on how it shoots, it appears to me they went back to the major overgassing of the pre 2017 timeline from what I understand... anyhow, should be fixed now. Thanks again. I have an 11.5" DDM4V7s upper and I wouldn't necessarily say it was over gassed bad. But I decided I'm not going to run it unsuppressed so may as well make it run optimally for that. I also pretty much only use 5.56 military clone ammo like M193, M855, and MK262. So I went with a .057" tube and am running it with a H2 buffer and regular carbine spring. It ejects that ammo at a consistent 3:30-4:00 ejection pattern with my YHM Turbo 3. |
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Posted: 5/7/2024 7:20:59 AM EDT
[#11]
Quote HistoryOriginally Posted By JBecker_72: Glad you got it to work. As for the tube size, the stock one is just a milspec tube. The gas port in the barrel is what determines how it runs. The BRT tube is just a restrictor so to speak. I have an 11.5" DDM4V7s upper and I wouldn't necessarily say it was over gassed bad. But I decided I'm not going to run it unsuppressed so may as well make it run optimally for that. I also pretty much only use 5.56 military clone ammo like M193, M855, and MK262. So I went with a .057" tube and am running it with a H2 buffer and regular carbine spring. It ejects that ammo at a consistent 3:30-4:00 ejection pattern with my YHM Turbo 3. @JBecker_72 Preset tube or configurable? |
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Posted: 5/7/2024 7:53:33 AM EDT
[#12]
Quote HistoryOriginally Posted By TGWLDR: @JBecker_72 Preset tube or configurable? |
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Posted: 5/7/2024 8:00:41 AM EDT
[#13]
Quote HistoryOriginally Posted By JBecker_72: Preset tube Quote HistoryOriginally Posted By JBecker_72: Originally Posted By TGWLDR: @JBecker_72 Preset tube or configurable?  Similar to my mine minus the spring, Sprinco blue on my end. |
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SC, USA
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Posted: 5/7/2024 8:37:07 AM EDT
[Last Edit: DVCNick]
[#14]
Quote HistoryOriginally Posted By JBecker_72: Glad you got it to work. As for the tube size, the stock one is just a milspec tube. The gas port in the barrel is what determines how it runs. The BRT tube is just a restrictor so to speak. I have an 11.5" DDM4V7s upper and I wouldn't necessarily say it was over gassed bad. But I decided I'm not going to run it unsuppressed so may as well make it run optimally for that. I also pretty much only use 5.56 military clone ammo like M193, M855, and MK262. So I went with a .057" tube and am running it with a H2 buffer and regular carbine spring. It ejects that ammo at a consistent 3:30-4:00 ejection pattern with my YHM Turbo 3. Wow that seems really small. They sent me an .073" tube based on my inputs. (I see yours is an 11.5 barrel as well) I definitely will shoot it unsupressed at least half the time though, will see how she runs soon. |
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Posted: 5/7/2024 9:44:05 AM EDT
[#15]
Quote HistoryOriginally Posted By DVCNick: Wow that seems really small. They sent me an .073" tube based on my inputs. (I see yours is an 11.5 barrel as well) I definitely will shoot it unsupressed at least half the time though, will see how she runs soon. Yours sounds to be a 50/50 supressed/unsupressed option. And yeah, 10.3" vs 11.5" are 2 different animals. |
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Posted: 5/7/2024 10:12:01 AM EDT
[Last Edit: CATM]
[#16]
Keep your broken punch, clean up the tip of it and use it as a starter punch. Always use a starter punch to get the pin moving. Then follow with a regular 1/16" roll pin punch. 1/16" punches are so fragile that even Snap-On and Proto punches will bend on a carboned-in roll pin.
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SC, USA
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Posted: 5/7/2024 11:11:18 AM EDT
[#17]
Quote HistoryOriginally Posted By CATM: Keep your broken punch, clean up the tip of it and use it as a starter punch. Always use a starter punch to get the pin moving. Then follow with a regular 1/16" roll pin punch. 1/16" punches are so fragile that even Snap-On and Proto punches will bend on a carboned-in roll pin. Will do, thanks. I feel like they had to put something on this pin (rocksett?) to get it that tight... Upper is new with less than 500rds on it. I've taken apart a number of factory built uppers, and just off the top of my head, on Colt, LMT, PSA, BCM, Laure, I've never seen a gas tube roll pin that didn't easily tap right out as long as the barrel was well stabilized. New pin went in as normal, so that would seem to eliminate an undersized hole in the gas block as a potential cause? |
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Posted: 5/8/2024 9:50:10 PM EDT
[#18]
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Posted: 5/9/2024 2:09:09 AM EDT
[#19]
We cover how to remove stuck gas tubes and roll pins in our Armorer courses. The gas tube roll pin is 5/64" in diameter. If you try and use a 1/16" punch, it may come out, but we see lots of bent and broken roll pins if you try and use this punch as it is too small and doesn't fully support the pin to get it out. Get a 5/64" punch. Apply a little Kroil to the roll pin. Brace the front sight base on a bench block, or the gas block on a bench block in the V-groove, making sure that the roll pin going to to get pounded into the bench block, and simply tap the roll pin out with a few hits on the 5/64" punch and the roll pin will come out.
Next is removal of the gas tube. If the gun hasn't been shot much, you should have a fairly easy time of removing the gas tube as it can usually be done with your fingers. If the gas tube is stuck, then you can either try a gas tube wrench, or some Sully gas tube vise jaws. The gas tube wrench can be applied and tightened about 1" behind the gas block/front sight base, and try and rotate the gas tube, if it will rotate then simply pull the gas tube out as you rotate it slightly both directions. If the gas tube won't budge, usually caused by a heavy carbon build up, then insert the gas tube into a set of gas tube jaws, and then place the gas tube jaws into a bench vise so that the jaws are level with the top of the vise jaws, and tighten the vise down to get a firm hold of the gas tube.    Then carefully try and rotate the upper/barrel to see if the gas tube will spin. If it won't rotate/spin, don't force it as I have had to deal with getting a broken gas tube out when someone try to force it and broke the gas tube off inside the front sight base/gas block. So if it is stuck and won't rotate, then apply a little Kroil to the roll pin hole on each side, and back of the gas tube where it enters the front sight base/gas block. Then use a propane torch or map gas torch to slowly heat the front sight base/gas block around the gas tube roll pin area, as you are heating for about 30-45 seconds, apply a light rotational pressure to the upper/barrel, and once things get hot enough and the tolerances expand you will feel the barrel rotate, at which time the gas tube is not loose, so stop applying heat, keep the barrel rotated to one side as far as you can, Then apply a drop of Kroil to the roll pin hole on once side, then rotate the barrel in the opposite direction until it stops, and apply a drop of Kroil to the other roll pin hole side. Now simply start to slowly rotate the barrel from side to side to let the Kroil do its magic, and you will quickly feel the gas to start to rotate very freely and easily. Now keep rotate as you push forward on the barrel or upper receiver, and the gas tube will come out of the front sight base/gas block. CY6 Greg Sullivan "Sully" SLR15 Rifles DefensiveEdge.com (763) 712-0123 |
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GA, USA
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Posted: 5/9/2024 9:00:13 AM EDT
[Last Edit: OTDR]
[#20]
Originally Posted By DVCNick: I've never seen any instance where this thing even offers the slightest resistance before... Got a DD MK18 upper, trying to install a BRT gas tube, and the roll pin absolutely will not move. I've put 30 seconds of torch on it, and broken two 1/16" punches.. it won't move a bit. Anyone encountered this before? I'm not even sure how this is physically possible. There is a reason for all this, video explains. Once the pin was initially pounded in with holes not concentric, can be hard to pound out. McMaster Carr Part # for the 5/64" Reamer is 2995A113 The problem with using the 5/64" punch for alignment is its about .005" smaller in diameter than the gauge you are going to make. Thus the punch goes thru but the gauge does not.  Gas Tube Roll Pin Problems and Resolution Tips |
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