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CashMonkey

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I just got a new barrel for my M4 Carbine, I'm looking for a gunsmith that can "marry" my old FSB to my new barrel. I've been told that I can get clamp on ones, but that they will loosen over time with vibration. I asked another dealer and the said they couldn't marry the FSB to my new barrel because there's no way to guarantee its alignment with the gas port hole in the FSB gas block and the port hole on the gas tube. And that "they'd have to drill a hole for the gas port?"

Wouldn't they just need to mill the slot where the taper pins would slide in to? Since my new barrel already has gas a gas port hole. Anyways if anyone could recommend someone to me please and Thanks!
 
Your dealer is not entirely correct . Its relatively easy with the right tools

The trick is to keep the FSB from moving when you drill the hole prior to taper pin reaming ( 2/0 taper )

FSB have a hole in the bottom due to the fact they need to drill from bottom up for the gas port hole during the manufacturing process. This hole serves no purpose after the gas port hole is drilled

This is the perfect spot to tap for 10-32 or 10-24 set screw

Align the FSB and screw down set screw ( I prefer do this in a mill or a proper jig )

You can ghetto it by vise gripping the FSB so it doesn't move on the barrel. I wouldn't do this personally

I then clamp in milling machine and center find the holes of the FSB , then drill and ream with 2/0 taper reamer

You can use the existing hole as a guide for the drilling but its far from ideal ( just I would use the smaller side obviously for the guide )

Lastly, a good clamp on FS such as PRI folding or Vltor will hold on surprisingly well

See the torture test half way down the page of the Vltor

http://w w.militarymorons.com/weapons/ar.optics2.html

They destroyed the index pin trying to get the front sight to move !
 
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I don't own this pic i found it on google but...

image.jpg


This what I need is some to drill or machine those 2 slots so that I can slide my old FSB to my new barrel, then taper pin it in for a more secure and permanent set up.
 
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