Gas block / handguard questions

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  • hpclayto

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    Im not very AR savvy. I have a 16” rock river LAR 15. It has a carbine length gas system with an A2 style front sight/gas block. It’s super cramped and I prefer to shoot with my arm more extended. I would like to add a longer (13 or 14 inch ) handguard to it and am trying to figure out the best way to go about it.

    I’ve seen people cut down the stock sight/gas tube to be able to fit a handguard over it. I’m more inclined to do this as I know the gun runs with it. This is my patrol rifle so reliability is the most important thing to me. If I did go with an aftermarket low profile gas block, how do I know what to get and if my gun is going to like it? Are they pretty much all the same? I know they make adjustable ones, is that what I need to get to fine tune it? Are the ones with set screws good to go or do I need to get one and have it pinned?

    Another option would be to get a replacement drop in handguard that has a cut out for the FSB. I know there are a few companies that make them (Ones I’ve seen are crazy expensive).

    I also came across this, it would get me what I’m after. Haven’t found any real world reviews of it though so maybe that’s saying something.


    https://www.midwayusa.com/product/1003229573

    one of the perks of getting a longer handguard and new front sight would be the increased sight radius. Probably a moot point as I’m not likely to be taking any long range shots but still.

    Thanks in advance.
     

    BR8818

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    If your rifle functions good now I dont see the need in buying an adjustable gb I'd just cut down the fsb. If you do end up buying a new gb you'll need to know the diameter. Set screw gb work fine in my opinion I've never had one come loose the only gas blocks I have that are pinned came that way from the manufacturer.
     

    rkwhyte2

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    You don't need a GB with a set screw the barrel already has been drilled for a pin. Just remove the front sight and install a GB or as BR8818 said have the front sight cut down.
     

    halfmileharry

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    Don't cut off the original sight post/gas block. Remove it and save for later.
    Buy a quality gas block and be done with it. You can always switch back if you ever decide to put it back stock. Once cut down it's not replaceable.
    I repeat quality gas block. AR gas blocks basically only come in a couple of sizes but like anything AR there's hundreds of companies punching out stuff for them
    I use BCM gas blocks now. Quality and reasonably priced.
     

    ditcherman

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    You don't need a GB with a set screw the barrel already has been drilled for a pin. Just remove the front sight and install a GB or as BR8818 said have the front sight cut down.
    Is this pinned config specific to the A2 type sight/gas block? So no setscrew detents in those barrels? That would seem to be very specific gas block, I've only seen setscrew but have never really been looking for anything else.

    OP, I have a couple of overgassed rifles and am just learning my way around the adjustable gas block, it seemed to me the best thing to treat the problem not put a band aid on it, although the band aid, (heavier buffer, stiffer spring) was more available and cheaper that adjustable gas blocks when I ordered. It looks like they've came back some. All that to say check availability first! If you do cut it down and don't like it you can always put an A2 gas block back on.
    Also, isn't the barrel nut different between a clamshell type handguard and a free float? You might be getting into changing this as well. Then you can look at a barrel. Then you start looking at a new gun. Ask me how I know.
    Best of luck.
     

    TangoFoxtrot

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    Before you do anything, post a picture of the base of the case of a fired round.. i say this because 90% of OTC AR rifles are over gassed to ensure they will shoot a wide variety of ammo. There some pretty inexpensive ways to address over gassing.

    Many benefits to correcting over gassing as well. I see alot of broken extractors from over gassing

    But i would agree adjustable gas blocks are not the best way to go necessarily. Buffer spring and weights are the 2nd best way.

    SLR adjustable and non adjustable. If your wanting to goto free float i would go with a clamp on style, ive seen many times where the set screw type do not line up do to tolerances. The SLR you just gap it .0025 from the shoulder and your good to go. Just my opinions and experience

    BTW odenworks makes some pretty slick hand guards at a reasonable price

    Sent from my SM-N975U using Tapatalk
     

    hpclayto

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    You don't need a GB with a set screw the barrel already has been drilled for a pin. Just remove the front sight and install a GB or as BR8818 said have the front sight cut down.

    I guess I hadn't thought about that. I'd just need to sure the gas block I was getting was able to be pinned, which is harder to find than I imagined.
     
    Last edited:

    hpclayto

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    Don't cut off the original sight post/gas block. Remove it and save for later.
    Buy a quality gas block and be done with it. You can always switch back if you ever decide to put it back stock. Once cut down it's not replaceable.
    I repeat quality gas block. AR gas blocks basically only come in a couple of sizes but like anything AR there's hundreds of companies punching out stuff for them
    I use BCM gas blocks now. Quality and reasonably priced.

    Is that your only reasoning as to why? Putting it back to stock is not something I'm concerned about.
     

    hpclayto

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    Is this pinned config specific to the A2 type sight/gas block? So no setscrew detents in those barrels? That would seem to be very specific gas block, I've only seen setscrew but have never really been looking for anything else.

    OP, I have a couple of overgassed rifles and am just learning my way around the adjustable gas block, it seemed to me the best thing to treat the problem not put a band aid on it, although the band aid, (heavier buffer, stiffer spring) was more available and cheaper that adjustable gas blocks when I ordered. It looks like they've came back some. All that to say check availability first! If you do cut it down and don't like it you can always put an A2 gas block back on.
    Also, isn't the barrel nut different between a clamshell type handguard and a free float? You might be getting into changing this as well. Then you can look at a barrel. Then you start looking at a new gun. Ask me how I know.
    Best of luck.

    They're different but the handguards i've been looking at come with a new barrel nut, or am I missing something? I don't really need to go with a free float system, not a match rifle or anything. I just assumed that the front retainer (not the proper term I'm sure) for the handguard would be gone since I'd be removing or altering the FSB.
     

    ditcherman

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    In the country, hopefully.
    They're different but the handguards i've been looking at come with a new barrel nut, or am I missing something? I don't really need to go with a free float system, not a match rifle or anything. I just assumed that the front retainer (not the proper term I'm sure) for the handguard would be gone since I'd be removing or altering the FSB.
    I believe you are correct in thinking that the front retainer will be gone if the A2 gas block is removed. I know all the free float handguards I have ordered have come with a nut, but they’ve all been BCM, which may be somewhat proprietary.
     

    cosermann

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    Im not very AR savvy. ....

    You could also just get a new mid-length upper with a longer handguard. Done.

    Yeah, you can screw around with the gas block and rails and such, but you said yourself, you're not very AR savvy.

    Maybe something like this:
    https://bravocompanyusa.com/bcm-mk2-bfh-16-mid-length-upper-receiver-group-w-mcmr-15-handguard/
    https://bravocompanyusa.com/bcm-mk2-standard-16-mid-length-enhanced-light-weight-upper-receiver-group-w-mcmr-15-handguard/


     

    hpclayto

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    You could also just get a new mid-length upper with a longer handguard. Done.

    Yeah, you can screw around with the gas block and rails and such, but you said yourself, you're not very AR savvy.

    Maybe something like this:
    https://bravocompanyusa.com/bcm-mk2-bfh-16-mid-length-upper-receiver-group-w-mcmr-15-handguard/
    https://bravocompanyusa.com/bcm-mk2-standard-16-mid-length-enhanced-light-weight-upper-receiver-group-w-mcmr-15-handguard/



    Department won't allow that.
     

    BroodXI

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    They're different but the handguards i've been looking at come with a new barrel nut, or am I missing something? I don't really need to go with a free float system, not a match rifle or anything. I just assumed that the front retainer (not the proper term I'm sure) for the handguard would be gone since I'd be removing or altering the FSB.


    there are several out there that use the standard gi barrel nut.

    https://www.midwestindustriesinc.com/product-p/mctar-20xg2-blk.htm
     

    AllenM

    Diamond Collision Inc. Avon.
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    Personally I would cut the existing sight down and put on a new handguard and be done.
    I have never had an issue with set screw gas blocks but if it was my duty rifle pinned gives me more piece of mind
     

    hpclayto

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    Ah, ok didn't know what your constraints were.

    But, they'll allow you to dink with the gas block (which, if done incorrectly, can affect reliability)?

    Well I never said they were logical. I could probably talk them into approving a whole new upper but that's a lot of dough, not far off from a whole new rifle at that point and that's what I would probably do.
     

    hpclayto

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    Personally I would cut the existing sight down and put on a new handguard and be done.
    I have never had an issue with set screw gas blocks but if it was my duty rifle pinned gives me more piece of mind

    This is the route that I'm going to go.
     
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