GUN AR handguard and gas block question

Discussion in 'On Topic' started by jayhat, Feb 9, 2009.

  1. jayhat

    jayhat You have the personality of a dead moth.

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    I currently have a standard flat top AR upper. It has a standard triangle gas block/FSB and triangle piece that the handguards fit into.

    I want a free float 4 rail and a low pro gas block.


    If I got this handguard and gas block would they work together?

    http://www.adcofirearms.com/itemdetails_.cfm?inventorynumber=2422

    Midwest Industries Railed Handguard-MID FF
    [​IMG]


    Vltor Gas Block-clamp Blackened SS

    [​IMG]
     
  2. yar1182

    yar1182 New Member

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    should work. I really like the look of the extended handguard that goes over the LP gas block. I would also recomend a adjustable gasblock like hte JP. Then you can dial down the gas to get a softer recoil impulse.
     
  3. jayhat

    jayhat You have the personality of a dead moth.

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    Yeah i do to.

    So with a free float it doesn't matter what size handguard right? I could just get a rifle length so it would go over the top of the gas block?
     
  4. yar1182

    yar1182 New Member

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    yeah that is generally how it is done.
     
  5. Soybomb

    Soybomb New Member

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    If you're doing this as a DIY thing, a regular a2 fsb can just be hacked off, if you're going to put it under a rail you won't see it and it will be pinned in place.
     
  6. yar1182

    yar1182 New Member

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    True. I much prefer a gas block that is not pinned to the barrel. Easier to remove to clean the gas tube.
     
  7. Soybomb

    Soybomb New Member

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    I've yet to need to clean or replace my gas tube and will take the reliability of a pinned in place gas block. One installed with set screws on dimples in the barrel would be adequate I'm sure.
     
  8. :werd: If this is my only rifle, or one that I would intend to use for "any" situation, then give me a pinned, non-adjustable gas block for the utmost in reliability. If this is a secondary rifle for having fun at the range, and I have something else to fall back on, then I'd take an adjustable gas block that's held on with screws.
     
  9. McCroskey

    McCroskey Jonny, what can you make out of this? OT Supporter

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    Just knock the pins out of your existing block, hack off the site post, paint, reinstall. With some time and a dremel you can clean it up nicely.
     
  10. yar1182

    yar1182 New Member

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    It maybe because I shoot way more than most. I have never had a problem with a removable set screwed gas block although I've only used quality ones like the JP. The 1st generation JP gasblock had set screws that touched the barrel. My smith made slight dimple holes so they line the same every time. The newest gneration JP gasblock I currently have the bolts run crosswise and do not tough the barrel. They just squeeze the gas block tighter around the barrel. Again no issues you just got to eyeball that it's centered more carefully. The adjustable gasblock is a major benifit. The gun is less dirty and not as overgassed. Softer recoil impulse and the gun seems to cycle faster though I'm sure that is part of the whole system with lightened bolt, buffer, carbine spring, and short reset trigger. The adj gas block is a major component of this though. I did have the gas hole on my barrel drilled out to a maximum diameter so that I have even more adjustability, and to be more forgiving if the gas block is misaligned (never happened but just in case). The gas block is on there you can't twist it off center with your hand. With a tool maybe but you would have to do it really hard. I also blue loctited the adjustment screw so it does not wander (I'm paranoid about my rifle settings).

    I have had several instances where I had to clean my gas tube. Again maybe it's because I shoot more. In fact I can feel when a gun is restricted by not enough gas. Then I know it's time to yank that tube out and scape it out then soak in solvent. then swab.

    You guys not cleaning the gas tubes probably have over gassed guns. The tube builds up with carbon and then you feel the gun is actually running betters because it is no longer over gassed. That is until it is constricted enough that it is under gassed and you get short stroking, or failures to cycle.
     
  11. The vast majority of shooters never clean their gas tubes, and by your logic there should be people all over the place having issues. The fact is that there are lots of people with tens of thousands of rounds through their weapons that have never cleaned their gas tubes, and they don't have these issues.
     
  12. fatmoocow

    fatmoocow bored OT Supporter

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    vltor will fit under any free float rail, they are as low profile as it gets.

    +1 for simple pinned gas block. Adjustable gas blocks are for suppressors. More shit to fail/adjust

    If you're going to yank out the gas tube why remove the gas block? Just push out the gas tube pin and pull out the tube. Also you shouldn't be pulling your gas block in the field anyway. If you're doing it you should be in a shop where you have a punch and time. You're also going to yank the forarm off, and flash hider/comp if you want to remove the block.

    My vote is buy a vltor VIS so you can take your barrel off and on like it's a scope and then you can clean whatever you want with no effort. Sell your current upper for some insane price on barfcom or keep for a backup.

    I did the math when I put mine together and it's not much more (if you where also buying an upper) because of a couple factors. So you pay ~640 for VIS, vs. $300 or so for a nice rail. You can now go with simpler scope setup as you can mount your scope on standard rings as far forward as you want without a $215 dollar Larue mount. So save at least 100 on rings + $100 to sell your upper + 300 for a rail = you're only paying about ~140 extra to be a baller, have qd barrel, continuous rail, and milled upper.
     
  13. yar1182

    yar1182 New Member

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    I'm sure you've seen how much carbon is on the inside of a bolt carrier. How do you think that carbon gets there. It goes though the gas tube. I'm sure if you bothered to do it and scraped out your gas tube you would be surprized how much crud you have in there. For people that shoot a lot the gas tube needs to cleaned. I do not clean mine all the time, maybe once or twice a year, but it is a part that needs to be serviced.

    The truth is most people do not really shoot that much or they do not push their rifles. Every other new shooter at the 3 gun matches show up with a rifle that does not work. It works fine for range plinking but once pushed that is where stuff like gas issues show up. Even though you may not of experieinced a gas releated rifle malfuntion it is still wise to understand their causes and take preventive measures
     
  14. My mind, you blew it. I was under the impression that the magic AR pixies put it there. To allay your concern, I have bothered to clean my bolt carrier, more than once even. Surely you realize that searing hot gas moving through a small tube at tens of thousands of PSI isn't going to allow a blockage to form. This is most likely why people like Pat Rogers recommend NOT cleaning the gas tube. Pat is backed up by policies to the same effect implemented by law enforcement groups, armed services, and manufacturers' armorer courses. I have a copy of the Marine Corps rifle marksmanship manual too, and they discuss cleaning in detail, they never tell you to do anything other than carefully wipe down the outside of the gas tube. I'm sure they have an understanding of how this all works too.

    Obviously, there will be carbon in the gas tube, and nobody has ever claimed otherwise. Now, if you're running an adjustable gas block where you can dramatically reduce the pressure in your gas tube, I can see how you would form harmful deposits. The rifle was designed to operate within certain parameters, and when modifications change those parameters it can affect the function of the rifle. If you want to know the "how and why" behind the carbon buildup in the bolt carrier, think about the fact that as the searing hot very-high-pressure gas exits the gas tube it cools rapidly as it expands into the much larger volume of the carrier. These are prime conditions for buildup of deposits, much different from the environment in the tube itself.

    Again, the rifle was designed to work a certain way, and it works wonderfully. When people start changing things (adjusting the pressure used to operate the gun) it changes the way the gun works. I'm not saying it's bad to use an adjustable gas block. In various situations it is certainly advantageous. One must be mindful though of all the effects of doing so though. What works for gun games (where ones life isn't at stake) doesn't necessarily apply to all situations, and the "overgassing" that is so derided in some situations is the source of reliability in others.
     
  15. Soybomb

    Soybomb New Member

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    With reliability in mind, I'd have no trouble running a gas block with set screws as long as the barrel had dimples for a little extra insurance, I might be tempted to stake the screws if not high temp loctite.

    I don't shoot nearly as much as you yar although my upper does see .22lr as well. So far no issues with a mid gas system on a 16" barrel. There's a spare tube in the parts bin if it ever turns into a problem.

    I suspect the problems with rifles seen at 3 gun matches have more to do with the goobers building the rifles (remember the nail file sight install thread a few days ago?) and the crappy parts they use than clogged gas tubes for the most part.
     
    Last edited: Feb 9, 2009
  16. yar1182

    yar1182 New Member

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    Well if Pat Rogers said so then it must be true. Lets rub vagisil all over our rifles.
     
  17. Sorry, but I trust Pat rogers, the Army, the Marines, various police departments, and the manufacturers of the rifles more than you in this case. They ALL say not to stick stuff in the gas tube. I've also explained to you how it's possible that you with an adjustable gas block would get worse fouling than someone without an adjustable gas block. You don't want to address that though. I guess when you really don't have anything to say in your own defense you can just make a stupid ad-hominem attack on Pat Rogers. :rolleyes: I'm not some Pat Rogers sackrider from barfcom, I just recognize that he has tons of experience and is trusted by many other people who are also well respected.


    Keep in mind that what works at 3-gun matches isn't the final arbiter of what is best in every situation.
     
  18. yar1182

    yar1182 New Member

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    I just don't understand how anybody no matter what kind of athority they claim to be can say you do not need to clean a major mechanical part of a machine that people stake their life on. How the heck does that make sense. I suspect it is more of a concern that they do not think the average shooter is qualified to break down, clean and reassemble a gas tube into the rifle without bending it up, or fucking up the installation.

    A lot of people are hung up on the competition shooting things. That's just ingnorance. You need to look for innovation and advantages in all arenas. The militarty and the law enforcement are fairly locked in their thinking but have been coming around.

    I did a demo for the Torrance Swat team last week. They are interested in putting micro reflex dot sights on the G21 sidearms. I showed them all the competition stuff we are doing and they wish their department decision makers were forward enough thinking to let them run some of our equipment.

    As far as a adjustable gas system producing more carbon than a non adjustable gas system that is debatable but should be a non issue. Just clean the gas tube every now and then. I would say it's more an issue with how much and how fast competition shooters are pushing their rifles. Even if your rifles is shooting fine I want to make sure I got a clean and completely reliable rifle before I show up at a match I care about. I don't see why a solider or LEO would not want the same if he is putting his life on the line.
     
  19. phrozenlikwid

    phrozenlikwid New Member

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    MG, you don't remember where you seen that Pat Roger's article do you?

    I'm on the fence with this one (though I'm not an AR guy and don't have much of an opinion). To me it makes sense to clean it, and I've actually helped my 'smith clean them out on rifles that had problems running, that ran fine afterwards. Personally, If you aren't running a .mil configuration, I'd think the adjustable gas port would make a lot of sense and perhaps allow you to nip some gas issues in the butt without sending your shit off to a pro.
     


  20. How about the idea that they don't do it simply because it's not necessary? Of the billions of rounds fired from AR style rifles by our armed forces wouldn't you expect there to be all sorts of problems if it really was necessary to clean the gas tube? The fact is the rifle was designed to work without that part being serviced, and it does work. Our armed forces aren't buffoons, surely they could remove and reinstall a gas tube if it was necessary, and they were shown how to do it. But it isn't necessary.

    Ignorance is the mentality that leads one to think that anything that applies in one area of shooting automatically applies in all areas.

    I wouldn't say it's "debatable" about adjustable vs. non-adjustable when it comes to reliability. From your own statements, gas tube cleanliness is important in an adjustable system. You said that yourself, and you warned about the malfunctions ahead if it wasn't cleaned. On the other hand, we have countless people who have NEVER cleaned their non-adjustable system's gas tube and haven't had any of the issues you describe seeing. On top of all that is the science that a hotter, faster-moving, higher pressure gas is less likely to suffer buildup than a slower moving, lower pressure, cooler gas.

    As to the idea that "I [you] would say it's more an issue with how much and how fast competition shooters are pushing their rifles." That's ridiculous. If you want to make believe that shooting a few magazines per stage out of your rifle at a match is anything like being in an actual firefight, then you're deluding yourself.
     
  21. The article is here.

    http://forums.offtopic.com/showthread.php?t=3951955

    Not just this article. Get your hands on any of the armed services' field manuals. They all say the same thing.

    Also, the part in bold... What we seem to be seeing is the exact opposite. A hotter, faster, higher pressure gas is going to be less prone to making such deposits. Indeed, from Yar's experience with needing to clean his gas tube and the experience of hundreds of thousands of soldiers who have never cleaned their gas tube, it shows that the issues are with the systems that run at lower pressures.
     
  22. Soybomb

    Soybomb New Member

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    In fairness to the other side, the army service manual does include blocked gas tube as a possible problem. My guess is that it rarely happens.
     
  23. Are they talking about actual carbon blockage, or foreign material / crushing damage?
     
  24. fatmoocow

    fatmoocow bored OT Supporter

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    This is more than enough reason alone.

    The reason the carbon doesn't really matter beyond the tempretures and pressures involved, is because the diameter of gas tube is way bigger than the diameter of the hole in the barrel. even if a gas tube was 75% filled with carbon and it would still be larger than the gas port hole.

    Trying to shave that last percentage of recoil or tuning everything to perfection isn't going to result in reliability. Reliability comes from:

    1. good ammo
    2. good magazines
    3. a wet gun
    4. not fucking anything up

    Guns that go down are generally a result of never being set up right to begin with. Random barrels with random gas port holes random parts, cool guy gear, gun show buffers and springs etc.all falls under fucking things up. Otherwise you're just going to go through a certain number of bolts and your shit should run.
     
  25. yar1182

    yar1182 New Member

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    Actually there are also plenty of factory or issued rifles that are dogs out of the box. They just don't run reliably or run at all.

    I really don't understand this fasination with keeping everything "stock". Many times these parts are contracted out to the lowest bidder, quality control is a non factor, it's loosey goosey so it can be mass assembled with no fitting.

    Use parts that work. While there is a lot of aftermarket stuff that is garbage, there is just as much stuff that is superior to the factory part. Otherwise there would be no aftermarket market.

    A 25% restriction of the gas tube would dramaticly change the way a rifle cycled. It would be really sluggish if it didn't stop working all together or repeatedly short cycle.
     

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