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Posted: 5/3/2016 10:59:06 PM EDT
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I bought a barrel that has a rifle length gas system, and I installed a low profile gas block on it. I then installed my free float quad rail, which measures exactly 12 inches, no more, no less. The quad rail leaves the gas block uncovered along with about 1 inch or 3/4 inch of gas tube showing. What is wrong? Is this normal or is something messed up?
Thanks, John |
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Quoted:
I wouldn't do that, unless you run exclusively with gloves. Or you're just a daylight range clown who shoots a few rounds and goes home with the barrel cool......  I won't do it again, the first time I did it was back in '79 and I had to do a hell of a lot of push ups on the punishment range when I first joined the Army! |
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Quoted: CMP rules might allow a longer handguard, but that is something I would not want. If anything I might want s 12.5 inch or 13 inch handguard. Current CMP rules allow a scope so I do not want a FSB in the scope's view.  That being said, with ~4x magnification an FSB won't be in the way. |
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Quoted: CMP rules might allow a longer handguard, but that is something I would not want. If anything I might want s 12.5 inch or 13 inch handguard. Current CMP rules allow a scope so I do not want a FSB in the scope's view. You won't see a front sight with a 4x scope. Maybe a slight shadow, but it won't be in the way. |
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Quoted: I bought a barrel that has a rifle length gas system, and I installed a low profile gas block on it. I then installed my free float quad rail, which measures exactly 12 inches, no more, no less. The quad rail leaves the gas block uncovered along with about 1 inch or 3/4 inch of gas tube showing. What is wrong? Is this normal or is something messed up? Thanks, John Not adding up. Pictures??? |
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Not adding up. Pictures??? Quoted:
Quoted:
I bought a barrel that has a rifle length gas system, and I installed a low profile gas block on it. I then installed my free float quad rail, which measures exactly 12 inches, no more, no less. The quad rail leaves the gas block uncovered along with about 1 inch or 3/4 inch of gas tube showing. What is wrong? Is this normal or is something messed up? Thanks, John Not adding up. Pictures??? I can post a picture when I get home. I mean that the handguard stops before the gas block and there is about 1 inch of gas tube exposed past the handguard before the gas tube connects to the gas block. I am not sure what is not adding up, the handguard is not long enough to cover the last inch of gas tube and the gas block. |
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"12 inches" is a nominal description of a rifle length handguard, not an exact specification.
The manufacturer of your handguard apparently failed to understand that. Probably should pick a handguard from a better manufacturer. The KAC handguards used on the Mk12 were apparently made short so as to fit behind a standard FSB and handguard ring. One should not take this setup as an endorsement of the concept as it's really a bad idea, the gas tube should be covered for both heat protection and durability reasons. |
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Quoted:
The US military has an exposed gas tube on all their MK12s This is an appeal to authority and an inherently flawed argument. Yes, they US military has an exposed gas tube on their MK12s, but that fact alone does not mean anything without elaborating on why the US military chose to outfit their DMRs with shorter handguards and exposed gas tubes and how that reasoning affected their final configuration. I would hazard a guess at this configuration being the result of recycling stockpiled parts due to budgeting concerns rather than it being The Right Way to build a rifle. If they were to buy new parts made for the task, I can say for sure that they would not have an exposed gas tube on their rifles, regardless of whether or not it's a realistic risk. Idiot teenagers/raw soldiers can and will break anything you hand to them that they don't have a personal financial stake in, and the military accounts for that need for durability. |
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Quoted:
Thank you so much. Do you think that much gas tube exposed is a problem? I thought 12 inch handguards were made for rifle length gas systems. 12 inch rifle length hand guards are correct for rifle length gas systems, with a FSB installed. The hand guard will fall just short of the FSB if it is free floating, and the front of the hand guard will lock into the hand guard cap if it is a "drop-in" system. |
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Quoted:
I really wish more companies would make a true rifle-length rail. As it stands now DPMS and MI seem to,be the only ones that have a free float handguard that fit properly behind the FSB What do you mean by "true rifle length"? I am sure the term is correct I am just unfamiliar with some of the lingo. |
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Quoted: This is an appeal to authority and an inherently flawed argument. Yes, they US military has an exposed gas tube on their MK12s, but that fact alone does not mean anything without elaborating on why the US military chose to outfit their DMRs with shorter handguards and exposed gas tubes and how that reasoning affected their final configuration. I would hazard a guess at this configuration being the result of recycling stockpiled parts due to budgeting concerns rather than it being The Right Way to build a rifle. If they were to buy new parts made for the task, I can say for sure that they would not have an exposed gas tube on their rifles, regardless of whether or not it's a realistic risk. Idiot teenagers/raw soldiers can and will break anything you hand to them that they don't have a personal financial stake in, and the military accounts for that need for durability. Quoted: Quoted: The US military has an exposed gas tube on all their MK12s This is an appeal to authority and an inherently flawed argument. Yes, they US military has an exposed gas tube on their MK12s, but that fact alone does not mean anything without elaborating on why the US military chose to outfit their DMRs with shorter handguards and exposed gas tubes and how that reasoning affected their final configuration. I would hazard a guess at this configuration being the result of recycling stockpiled parts due to budgeting concerns rather than it being The Right Way to build a rifle. If they were to buy new parts made for the task, I can say for sure that they would not have an exposed gas tube on their rifles, regardless of whether or not it's a realistic risk. Idiot teenagers/raw soldiers can and will break anything you hand to them that they don't have a personal financial stake in, and the military accounts for that need for durability. KAC SR15 MOD 1 has exposed gas blocks, and they don't build a rifle from the parts bin. Let's also not forget that every rifle with a FSB also has an exposed gas block. |
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