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Posted: 4/30/2015 3:53:29 PM EDT
So after much debate, I'm finally going to build something outside of my comfort zone. Normally stick to building rifles with the standard A2 FSB because that's what Uncle Sam taught me to work on. I literally have no experience what so ever with gas blocks with the exception of a SAA upper with a gas block that's on my fiancé rifle.

The plan for the build is to have a nice accurate rifle with fixed A2 buttstock (perfect lop for me) and a Primary Arms 1-4x24 scope.

My question is, what do I need to know before I go buying a barrel, gas block, and FF handguards. What recommendations would some make? I have all the necessary tools for the build, I'm just a little nervous cause I've never dealt with gas blocks. Thanks in advance for any and all advice, I've been going through the archives reading up but figured I'd try to get some fresh ideas.
Link Posted: 4/30/2015 4:14:51 PM EDT
This may not be of help but my middy is the 6th post down...
http://www.ar15.com/archive/topic.html?b=3&f=4&t=571951

Those that use optics over the A-frame FSB say it goes out of view after 3x or so.
If you didn't like the FSB, you could always shave it...
Link Posted: 4/30/2015 8:18:09 PM EDT
Ive thought about that, but wanted the cleaner look though it's a good option
Link Posted: 4/30/2015 8:43:28 PM EDT
It's pretty straight forward. Pay attention to the OD of the barrel at the gas port as you will want to get a gas block with the same ID, obviously. Set screw type gas blocks are pretty common. Some folks like to pin them for the added assurance. In my opinion it is not nessecary when you dimple the barrel and use the proper thread locker. If I were trusting my life the the rifle, I'd probably pin the block anyhow, just because. A lot of barrels come pre dimpled in one spot. There are some fairly inexpensive fixtures out there if the barrel you choose does not have that feature from the factory. Don't over think this, it's simple
Link Posted: 4/30/2015 8:45:41 PM EDT
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Originally Posted By crazysarge16:
Ive thought about that, but wanted the cleaner look though it's a good option
View Quote

Is your handguard going to fit over or even cover up the gas block?
I like the shaved down FSB because it rarely works loose or gets knocked out of alignment with the gas port.

I don't trust set screws and such, the old taper pinned FSB is ok in my book. Get a standard barrel and modify

Link Posted: 4/30/2015 8:56:38 PM EDT
I shaved down the FSB on my daughters carbine. Very easy to do. No need to remove it to do the work.
Link Posted: 4/30/2015 9:20:54 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Direct-Drive:
This may not be of help but my middy is the 6th post down...
http://www.ar15.com/archive/topic.html?b=3&f=4&t=571951

Those that use optics over the A-frame FSB say it goes out of view after 3x or so.
If you didn't like the FSB, you could always shave it...
http://www.hunt101.com/data/500/medium/Gas_Block1.jpg
View Quote


Damn nice work. One of the best chop jobs I've seen. Well done sir.
Link Posted: 4/30/2015 9:21:23 PM EDT
I would buy a barrel with no front sight gas block and also purchase a lo profile gas block that way it will make no difference what FF hand guard you buy.

Vince
Link Posted: 4/30/2015 9:51:57 PM EDT
I haven't decide which handguard I'm going for. The barrel will be 16", so debating about a 13" rail. Only thing besides scope that will be mounted is Harris bipods and maybe a small flashlight.

Will have to look into shave fsb more
Link Posted: 4/30/2015 10:09:43 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By foursixty:


Damn nice work. One of the best chop jobs I've seen. Well done sir.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By foursixty:
Originally Posted By Direct-Drive:
This may not be of help but my middy is the 6th post down...
http://www.ar15.com/archive/topic.html?b=3&f=4&t=571951

Those that use optics over the A-frame FSB say it goes out of view after 3x or so.
If you didn't like the FSB, you could always shave it...
http://www.hunt101.com/data/500/medium/Gas_Block1.jpg


Damn nice work. One of the best chop jobs I've seen. Well done sir.

Not mine.
I "borrowed" the pic from Google Images.
Link Posted: 5/1/2015 10:19:41 AM EDT
[Last Edit: 5/1/2015 10:21:45 AM EDT by bmyk]
That is the pic I was looking at when I cut down the one I did....
Concur with the FS not being an issue with optic or red dot. I have used Eotech, and now use an Aimpoint PRO and a 1x4 both with a FSB front sight. No problem.
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Direct-Drive:

Not mine.
I "borrowed" the pic from Google Images.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Direct-Drive:
Originally Posted By foursixty:
Originally Posted By Direct-Drive:
This may not be of help but my middy is the 6th post down...
http://www.ar15.com/archive/topic.html?b=3&f=4&t=571951

Those that use optics over the A-frame FSB say it goes out of view after 3x or so.
If you didn't like the FSB, you could always shave it...
http://www.hunt101.com/data/500/medium/Gas_Block1.jpg


Damn nice work. One of the best chop jobs I've seen. Well done sir.

Not mine.
I "borrowed" the pic from Google Images.

Link Posted: 5/1/2015 1:45:44 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bmyk:
That is the pic I was looking at when I cut down the one I did....
Concur with the FS not being an issue with optic or red dot. I have used Eotech, and now use an Aimpoint PRO and a 1x4 both with a FSB front sight. No problem.

View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bmyk:
That is the pic I was looking at when I cut down the one I did....
Concur with the FS not being an issue with optic or red dot. I have used Eotech, and now use an Aimpoint PRO and a 1x4 both with a FSB front sight. No problem.
Originally Posted By Direct-Drive:
Originally Posted By foursixty:
Originally Posted By Direct-Drive:
This may not be of help but my middy is the 6th post down...
http://www.ar15.com/archive/topic.html?b=3&f=4&t=571951

Those that use optics over the A-frame FSB say it goes out of view after 3x or so.
If you didn't like the FSB, you could always shave it...
http://www.hunt101.com/data/500/medium/Gas_Block1.jpg


Damn nice work. One of the best chop jobs I've seen. Well done sir.

Not mine.
I "borrowed" the pic from Google Images.



I prefer the FSB on my carbines (minus my fiancé rifle which has a gas block but I bought that upper complete before I started building, now I just look at it and think of how I could modify it to the better).

Just figured I'd try something different on a build, outside my norm. Plus this one will take awhile to complete since I have other ones ahead of it. Though the two ahead are just waiting for their lowers.
Link Posted: 5/3/2015 9:49:32 AM EDT
[Last Edit: 5/3/2015 9:53:35 AM EDT by airgunner]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By a308garand:

Is your handguard going to fit over or even cover up the gas block?
I like the shaved down FSB because it rarely works loose or gets knocked out of alignment with the gas port.

I don't trust set screws and such, the old taper pinned FSB is ok in my book. Get a standard barrel and modify
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By a308garand:
Originally Posted By crazysarge16:
Ive thought about that, but wanted the cleaner look though it's a good option

Is your handguard going to fit over or even cover up the gas block?
I like the shaved down FSB because it rarely works loose or gets knocked out of alignment with the gas port.

I don't trust set screws and such, the old taper pinned FSB is ok in my book. Get a standard barrel and modify

+1 to all of the above. I think a shaved down FSB is the way to go and has a very clean look when done well and its going to be covered by a long rail then that hardly even matters anyway. The only catch is, it depend on what barrel you want to go with? If you are looking for an SS Match type barrel, most of those don't come with a pinned on FSBs unless you find a NM type barrel.

The biggest thing for me is, I only trust pinned on gas blocks. Sure lots of people have set screw or clamp on type blocks with no issue but for me, pinned is the only way to go. Here's one I did for my SBR...



To be honest, I like the one in Direct-Drives post better and if I need to do it again, I would do it more like that.

If you really must do an aftermarket GB, you can have it pinned but that's not cheap (for what it is) but I would go setscrew over clamped and I would make sure the barrel was dimpled for at least one of the setscrews and then I would red locktite them in.
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