AR newb wants to install low profile gas block- any advice?

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  • led4thehed2

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    Oct 16, 2011
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    I want to remove the A2 front sight on my M&P15 Sport, and replace it with a low-profile gas block so I can use a red dot and/or scope.

    This would be my first attempt at something like this, and thus far I've not done a lot to modify my rifle. Lots of videos online- seems like something I can accomplish- but figured I'd reach out for opinions, suggestions, or maybe some "learn from my mistake" stories.

    Also, I'm open to suggestions as to which gas block to use. I've seen them as cheap as $5, and don't know anything about reputations of any of the companies making them.

    Thanks INGO...
     

    NyleRN

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    The pins on the FSB are tapered and only come out one direction. They're a pain to drive out. Cheapest gas block I'd use is YHM
     

    TheMachine

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    Feb 20, 2017
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    I plan on keeping the A2 gas block and just cutting off the front sight when I get a free-float handguard. Should be low-profile enough, I'd look into that first.

    But I'm also a noob, interested to hear what everyone else thinks.
     

    churchmouse

    I still care....Really
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    I plan on keeping the A2 gas block and just cutting off the front sight when I get a free-float handguard. Should be low-profile enough, I'd look into that first.

    But I'm also a noob, interested to hear what everyone else thinks.

    I have done his a few times for friends on short budget builds. It will clear the free float.
     

    Trigger Time

    Air guitar master
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    The ONLY benefit to doing this is to re-use the pin system that secures the gas block to the barrel even through an explosion. Because that's how solid the two pin system is.
    As long as your new rail covers the new low profile gas block (for bump protection) and you demple the barrel where the low pro gas block screws will go and use blue locktite on the screws then you will be fine.

    if you are going to cut the front sight post down (don't forget the sling attachment and the bayonet lug) you need to check the clearance with your new rail. For example some rails have just enough space to fit the exact profile of a LOW PROFILE gas block. (Like the Daniel defense mark 18 or block 2 style rails). In that case if you re-use the pinned on front sight posts not only do you have to cut it down but you have to physically sculpt it on a grinding wheel and finish it with a dremel or something to take rough edges off ect. So that when done it looks like an elongated low profile gas block. It is VERY VERY labor intensive and unless you do it yourself the time you have in it and the pin in the ass of it, by the end you will say "I should have just bought that $30 low profile gas block. Some gunsmiths won't even screw with it And if they do get ready to pay a **** load. Just taking off a front sight post is a ***** (all rifles are different as some just pop right off and others need pressed off with anhydrolic press no joke), I know one shop that sent it out for this and charged $50. It's a *****.

    another bit of advice. DO NOT SCRIMP AND BUY A CHEAP GAS BLOCK or gas tube!!! I have literally had people bring me parts that they bought online that were obviously made in China or here by the lowest bidder and made of probably pot metal. When installing the pin that retains the gas tube I've literally had the blocks chip apart!! I started refusing to install ****ty parts. Not only was It a waste of my time but also I knew the owner of the gun would later probably blame me when their rifle inevitably failed down the road.
    like mentioned above go with at least a YHM brand low profile gas block.
    so my advice, save some time and money and headache and don't be a cheap ass and buy a good low profile gas block and install it properly. You can even re-use the gas tube and pin!!
     
    Last edited:

    led4thehed2

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    You can also leave the front sight alone and use a red dot or scope. Just another option.

    True, I just find it irritating seeing the blur of the front sight in the scope. I've ordered the red dot first, and will give it a shot with the front sight still on and see if I feel like I REALLY want/need the low profile.
     

    Chase515

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    Jan 29, 2011
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    Go to menards and buy some punches. They have some that are tapered punches 10-12" long and really help getting the pins moving. It's ok to use a oversized punch to get the pins moving just switch to a 1/8" punch after it starts moving. Use a ball peen hammer and a very stable table or take it outside and do it on the sidewalk be careful and use wood and rubber mats on the concrete to keep from damaging your barrel. I used a troy low profile block on my last build 30$ and a spikes melonite gas tube 15$. Every time I install a low profile block I try putting it on backwards first. Don't ask me why I just make that mistake every time. If it goes on tight and not all the way down take it off and flip it over. Don't try to use a under sized punch they bend with the first whack of the hammer. If you we're closer I'd help you do it.
     

    Trigger Time

    Air guitar master
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    Go to menards and buy some punches. They have some that are tapered punches 10-12" long and really help getting the pins moving. It's ok to use a oversized punch to get the pins moving just switch to a 1/8" punch after it starts moving. Use a ball peen hammer and a very stable table or take it outside and do it on the sidewalk be careful and use wood and rubber mats on the concrete to keep from damaging your barrel. I used a troy low profile block on my last build 30$ and a spikes melonite gas tube 15$. Every time I install a low profile block I try putting it on backwards first. Don't ask me why I just make that mistake every time. If it goes on tight and not all the way down take it off and flip it over. Don't try to use a under sized punch they bend with the first whack of the hammer. If you we're closer I'd help you do it.
    chuck the gas block in your vise with leather teeth and install the gas tube first to avoid that problem :)
    make sure you don't install your gas tube upside down OP. The big hole faces down. Line up your pin hole and with a roll pin punch tap in the pin.
     

    TJ Kackowski

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    True, I just find it irritating seeing the blur of the front sight in the scope. I've ordered the red dot first, and will give it a shot with the front sight still on and see if I feel like I REALLY want/need the low profile.
    If you're irritated with the blur of the front sight, then you're not concentrating on the correct item in your sight alignment / picture.
     

    Chase515

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    chuck the gas block in your vise with leather teeth and install the gas tube first to avoid that problem :)
    make sure you don't install your gas tube upside down OP. The big hole faces down. Line up your pin hole and with a roll pin punch tap in the pin.

    Your right I should install the gas tube first. My garage is a mess and I need to clean off the work bench so I have a place to set a rifle and free up the vice for something other than holding a Ar vice block.
     

    KG1

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    If you spend more time looking for the tools you need than actually working on your project then that's a sign that your garage is too messy.
     

    Hop

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    I'd leave it and run a scope. TJ is correct. The blur will disappear when you concentrate on the reticle.

    Taper pinned gas blocks rock.
     

    saintnick81

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    I have a Vortex Sparc AR coming tomorrow. Planning to set it up for lower 1/3 cowitness. Leaving the front sight and putting on a flip up rear.
     
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