Question

[hendrixhendrix]

I purchased an AR15 SS heavy barrel upper and when I was boresighting it I noticed the bore was funky looking. I ran a patch through and it came out brown and so did three more patches. My question is, what color is bore lapping compound? I surely hope this is what it is cause it almost might be rust. I have it soaking now and will know more tonight. I welcome any ideas you have on this. Thanks.

 

[Unclenick]

Cosmolene and a lot of other anti-corrosion grease is brown. Indeed, the Liquid Alox bullet lube sold by Lee is actually an industrial rust inhibitor. Mineral spirits will dissolve it. Use multiple patches until it's gone. I'm glad you looked and spotted it. Shooting through that stuff can cause excess pressure and damage the gun and maybe you.

Not sure why an SS barrel would need that stuff except that they probably didn't passivate the stainless after manufacturing. Also, the maker maybe they just does it to all the barrels they make?