Will a magnesium AR receiver catch on fire from rapid firing?

I traded for one just pulled and previous owner said it was made of magnesium. No name of mfg. or material but it is lighter weight than other receivers made of aluminum.
Update: The top one is the one.
Update 2: Has anyone ever seen magnesium burn or just hearsay?
Update 3: That is anti seize on the barrel threads not bare metal.
Update 4: Correction it does indeed have a LOGO between forward assist and case deflector under the rail shaped like an old fashioned keyhole. Just got it and did not look close enough.
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