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10/25/2010 1:59:20 PM EDT
Whats the deal with the different 'types'? I bought one and it turns out the Taper pin holes were too high on the FSB so it wouldn't work with my barrel so are there different types as far as the taper pins go? Thanks!

ETA: I keep hearing "F" Marked FSB's and A2 FSB's so are these the two main types with different taper pin holes?
10/25/2010 2:29:05 PM EDT
[#1]
Front sight bases are drilled for the pins while installed on the barrel.  No two are alike.  

The F bases were designed for flat top receivers.  They are .04" taller than a standard base.

10/25/2010 4:31:09 PM EDT
[#2]
Quoted:
Front sight bases are drilled for the pins while installed on the barrel.  No two are alike.  

The F bases were designed for flat top receivers on carbines.  They are .04" taller than a standard base.



Fixed.
10/26/2010 3:41:57 PM EDT
[#3]
Thanks guys. I was kind of assuming there was specific dimensions manufactures needed to follow so FSB's would be universal with different barrels but i guess not
10/26/2010 7:11:38 PM EDT
[#4]
Ok.. new question.. I see all sorts of used FSB's on the EE selling so why buy them if they are not going to fit your barrel? I know you can put set screws in them but im assuming not everybody buying them is planning on tapping and putting screws in it.. so what does everybody do with em?
10/27/2010 3:45:45 AM EDT
[#5]
You can buy a YHM clamp on FSB they have a lot of options and are nice.
10/27/2010 6:15:01 AM EDT
[#6]
Quoted:
Ok.. new question.. I see all sorts of used FSB's on the EE selling so why buy them if they are not going to fit your barrel? I know you can put set screws in them but im assuming not everybody buying them is planning on tapping and putting screws in it.. so what does everybody do with em?


If they are pinning them, they are installing on new barrels.  You can drill a new barrel for a pre-drilled FSB.  It doesn't come out perfect but if you aren't looking for it, it's not that noticeable.    There's a DIY thread on how to do it in the Retro Forum, somewhere.
10/27/2010 7:25:44 AM EDT
[#7]
I've welded up holes on used FSB's and reused them.
10/27/2010 11:07:14 AM EDT
[#8]
That makes sense. I didn't think that many people had the know-how or the tools to drill for the taper pins (no offense to anyone) to re mount them.
10/27/2010 1:12:35 PM EDT
[#9]
Quoted:
That makes sense. I didn't think that many people had the know-how or the tools to drill for the taper pins (no offense to anyone) to re mount them.


There are a few around. Not many. I designed a jig for installing FSB's. Bravo sells them.

10/27/2010 1:15:38 PM EDT
[#10]
All it takes is a drill press and a taper reamer.  A small end mill helps, too.

http://www.ar15.com/forums/topic.html?b=3&f=123&t=511624
10/27/2010 9:03:36 PM EDT
[#11]





Quoted:





Quoted:


Front sight bases are drilled for the pins while installed on the barrel.  No two are alike.  





The F bases were designed for flat top receivers on carbines.  They are .04" taller than a standard base.











Fixed.
Fixed.  All milspec flat top uppers use the F marked FSB.
 
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