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Old October 15th, 2013, 11:38   #4
Stealth
Mr. Silencer
 
Join Date: Dec 2001
Location: Toronto
I'm not sure as to the function of the hex screws, but this is the URX2 (which your E-series rail is based on) - note 2 jam nuts with notches cut into it.

Look down into the rail - do you have those notches on your barrel nut?
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