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Old January 7, 2014, 11:03 PM   #1
Louca
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Some A2-style Front Sight Questions

I am thinking of building an AR with a standard (20") barrel and A2-style front sight. But instead of the usual A2 hand guard, I would like a free float hand guard that still looks like the original A2 one. This barrel, sight, and hand guard will all be separate parts (not pre-built). The barrel I am thinking of getting is from Brownells (080-001-017WB) as is the free float sleeve/hand guard (739-000-003WB). This is my first build, and I do have a friend that can help me and has most of the tools available.

But exactly what front sight to get is my question. Here are my questions regarding using a standard, un-drilled, pinned-style sight: How hard is it to be sure the sight is properly aligned? How can you know when the sight's gas hole is aligned with the hole in the barrel? I mean, once you drill holes, you're done with any fore/aft left/right alignment, I would think. How hard is it to drill the holes for the pins (especially into a stainless barrel)?

I guess an alternative to drilling and worrying about exact alignment is to use a clamped front sight kit from Armalite (EU0240MPKIT). One negative there is they are on continuous backorder and will come in who-knows-when. Anyone have any cautions against using a clamped front sight? If they really are that much easier to install, why don't more builders use them?

Lou
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Old January 8, 2014, 10:32 AM   #2
MtnCreek
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I didn't see the parts you listed.

The barrel should have a step in it's profile. When the FSB is all the way to the step, the gas holes should align. I would suggest getting a barrel that's already drilled for the FSB pin. Accurately drilling a hole into the radius of a barrel is way beyond my capabilities, YMMV.

I've installed a clamp on type front sight (PRI flip up). I aligned it by eye, zeroed at 100, then fired at ~30 and ~250 to check.
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Old January 8, 2014, 05:22 PM   #3
Louca
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Thanks MtnCreek. My parts above have Brownells numbers next to them. So you would have to go on their site to see the item. I guess I should have made click-able hypertext links and shown it like this:

The barrel I am thinking of getting is from Brownells (080-001-017WB) as is the free float sleeve/hand guard (739-000-003WB).

Your idea of getting an barrel with an installed sight and just taking it off is something I had not considered, but seems logical. Thanks.

Lou
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Old January 8, 2014, 05:50 PM   #4
Nathan
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Frankly, FSB to barrel mating is not generally a DIY deal. Buy a barrel with a pinned FSB. If you are OK with clamp on, set screw, etc, those barrels should be fine.

This is based on my own capabilities. Basically you MUST align the FSB pins to the barrel ext pin. Barrel exten. and FSB's have always been jobs for real machinists...
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Old January 8, 2014, 06:41 PM   #5
Louca
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Quote:
Basically you MUST align the FSB pins to the barrel ext pin. Barrel exten. and FSB's have always been jobs for real machinists...
That's exactly what I was thinking, and what I was worried about. I mean how would I know I had the sight exactly aligned correctly? And I have my new barrel also in the ante. I am pretty well convinced I am NOT going to put my own front sight on.

Lou
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Old January 8, 2014, 06:50 PM   #6
Nathan
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$30-$50 according to this site: ar15barrels.com
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