Blue Plastic-Like Residue Seen in Borescope

Bidwell

FNG
Joined
Aug 16, 2024
Messages
36
Hi, got a borescope and started looking at my rifle today. I noticed right away that there's this blue plastic-like residue near the crown. No where else. I use Barnes TTSX 130 grain 308 projectiles with the dark blue polymer tip. Is this what that's from? I've read that these tips don't melt so not sure what's going on. Getting good accuracy so it doesn't seem to be effecting much but would just like to know for sure what it is. I attached an image, any ideas?1735431160010.jpg
 

AZ_Hunter

WKR
Classified Approved
Joined
May 1, 2024
Messages
449
Copper oxidizes blue. Look at an old crusty penny or copper piping… also why patches with copper solvent will come out blue.
 
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Bidwell

FNG
Joined
Aug 16, 2024
Messages
36
Copper oxidizes blue. Look at an old crusty penny or copper piping… also why patches with copper solvent will come out blue.
Wow, well that thought definitely crossed my mind. Just was surprised how crusty and plastic like it looked. Must be it. Here's another picture just from my phone
 

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TaperPin

WKR
Joined
Jul 12, 2023
Messages
3,622
Wow, well that thought definitely crossed my mind. Just was surprised how crusty and plastic like it looked. Must be it. Here's another picture just from my phone
Somewhere I read an article about the chemistry of burning smokeless powder - there are all sorts of chemical residue, many of which are acidic, so that helps explain why copper turns green so quickly even in a dry climate.
 
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