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1/5/2005 7:46:24 PM EDT
Wanted to replace my Colt Sporter Target R6551 front sight base (FSB) with one with a bayonet lug.  Bought this from a guy who bought it new from M&A at a gunshow.  It's new with markings of "B99 (circled R1) 2"; it's definitely forged.  Here is the kicker...the distance between the pin holes is 1 1/2"...that's 1/8" too wide.  The stamping of the "UP and arrow" are barely visible.  Tried to install it on a Colt A2 gov't profile barrel, but the holes did not line up.  

WTF?  I thought all FSB pin holes are of the same specs.  All my other Colt and BM barrels measured exactly the same distance, 1 3/8" measured between center of holes.  

I know BM and Colt have the same spec, but what about other makers????  I now have a useless $30 FSB.  Is this made for other than Colt or BM??
http://img.photobucket.com/albums/v213/04eskimo/Colt018.jpg

This is the Colt FSB on A2 gov't profile barrel.
http://img.photobucket.com/albums/v213/04eskimo/ColtR6551.jpg

Beware of the pin holes distance if you plan to changeing the FSB.  I learned the hard way.
1/5/2005 7:52:49 PM EDT
[#1]
I think you are reading your tape wrong! The second picture measures 1-3/16" not 1-3/8".
1/5/2005 7:54:00 PM EDT
[#2]
Fireball, it looks like your FSB was drilled by someone who doesn't know what he's doing. Those holes didn't come that way from the factory-new FSBs typically ship without holes.

It sounds like a classic case of kitchen table gunsmithing gone wrong.

Sorry mate
1/5/2005 7:55:31 PM EDT
[#3]
The digit pic are a little distorted.  It's definitely 1 3/8" wide on Colt and BM barrels.  Just measured them again.
1/5/2005 8:35:13 PM EDT
[#4]
Looking at the rings that go around the barrel, the pin holes are fairly centered, front to rear, on each ring in the second picture. They are closer to the ends in the first picture.

There's your difference.



Lonny
1/5/2005 8:36:34 PM EDT
[#5]
Looking at the rings that go around the barrel, the pin holes are fairly centered, front to rear, on each ring in the second picture. They are closer to the ends in the first picture.

There's your difference.



Lonny
1/5/2005 8:48:01 PM EDT
[#6]
Even if the holes were "closer" to where they are supposed to be, chances are they still wouldn't have lined up perfectly, they seldom do.  Better to start with an undrilled one and go from there.
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