Removing gas block

[infideleggwelder]

I have a DPMS ar upper that has a gas block i`d like to replace. I got one set screw out, but the other just twists off Allen keys. Have not stripped it and would like to avoid that.
The set screw I removed has a white/beige residue on the threads. Is this a lock-tite type of compound? If so, what do I need to do to loosen this set screw?

 

[7.62mm]

Try heating with a propane torch and remove when warmed up, get a good set of Allen keys.

 

[rifleman338]

Like was stated above, some heat and a good set of Allen wrench like the Bondhus ones from KBC Tools should get the job done without rolling.

 

[trevj]

Heat, and if all else fails, you pick through your cheap selection of crappy driver bits to find the next nearest size up, in either metric or Torx tips, tap that gently in to the now well rounded cavity in the set screw, leave it in place, and use a ratchet and extension to turn the screw.

Carbide ball end burrs to eat away enough of the set screw to get a carbide drill in without completely hoopering it from having the cutting edges hanging up, and shattering.

 

[infideleggwelder]

Heat worked, upper is now at Complete Gun repair in St John`s, getting the A2 sight installed. hope to pick it up today and hope to get it to the range soon to test fire.