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Old 07-06-2013, 03:52 AM   #1
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Default 603 (M16A1) and A2 front sights?

I'm really into the idea of putting together a retro build and am looking for a bit of advice.

My first question was, is there any difference between a Colt 603/M16A1 front sight and the standard A2 sight, either functionally or cosmetically?

My second question is if no difference, would I be better off to find a barrel with the A2 front sight already attached? I want to go as close to correct as possible without too much headache. I realize that AR parts are a bit difficult to come by right now but I can't even find a listing for a pencil 20" barrel with the sight attached. Anybody have any tips, thoughts or suggestions?



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Old 07-06-2013, 03:54 AM   #2
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A1 only has side to side adjustment for sights and A2 has not side to side and up and down.



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Old 07-06-2013, 04:25 AM   #3
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Quote:
Originally Posted by darthjkf View Post
A1 only has side to side adjustment for sights and A2 has not side to side and up and down.
The front?

Is there any difference in the dimensions?
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Old 07-06-2013, 05:03 AM   #4
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Quote:
Originally Posted by sputnik1988 View Post
The front?

Is there any difference in the dimensions?
no. the barrel profile and handguards are the only diff between A1 and A2 barrel assemblies. the A1 can have one of three different flash hiders as well. the A2 only has the half birdcage (best all purpose flash hider for the AR15)

there currently arent any true 20" pencil barrels being made to my knowledge other than the occasional green mountain http://www.gmriflebarrel.com/militarysurplusriflesbarrels/ar-15--m16--m4--assault-rifle-barrels/m16-a1--556mm-20--112-twist-20-barrel even that one is sporting M4 cuts. you could try the folks at krieger or white oak.
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Old 07-06-2013, 05:39 AM   #5
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Apart from forging marks (markings varied over time and according to the supplier of the forging), machining the flash from the forging (only done on A1 FSB's), and a different diameter hole for a different diameter barrel (.625" vs .75"), I can't recall any other major differences between A1 and A2 FSB's. There may be some minor geometry differences that I can't recall.

Functionally, there is no difference between the M16A1 and M16A2 front sight blocks. Both have a sight tower that accepts the same pin, both have a bayonet lug on the front, and both have a sling swivel mount on the rear.

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Old 07-06-2013, 10:41 AM   #6
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I found a site that will reprofile a barrel, would this be worth doing?

http://www.adcofirearms.com/shopservices/shop_qnew.cfm?code=Contour%20Barrel

Also, correct me if I'm wrong, but even doing this, won't the barrel thickness under the FSB be incorrect?

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Old 07-06-2013, 11:25 AM   #7
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The A-1 sight is a 5 position tapered post. The A-2 sight is a 4 position straight, squared post

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Old 07-06-2013, 05:50 PM   #8
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http://home.comcast.net/~j_colt123/Improved%20M16A2_A3_A4%20Zero%20Target.pdf

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=7&ved =0CEQQFjAG&url=http%3A%2F%2Fohmr.ohio.gov%2Fforms% 2Fohmr2444.doc&ei=11nYUf2sCobc9ATVooDADQ&usg=AFQjC NEHs1n0xM27bussbBRM2dFsk74pBw&sig2=-eH3cp_2NG7WWWHHrgh-0g
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Old 07-07-2013, 04:31 AM   #9
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Quote:
Originally Posted by robocop10mm View Post
The A-1 sight is a 5 position tapered post. The A-2 sight is a 4 position straight, squared post
Forgot about that. The last M16A1 I used was in boot camp.
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Old 07-07-2013, 09:14 AM   #10
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One more question, If I end up going with an A2 sight, should it be a standard or F marked FSB?



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