i went to the range over the weekend with with my sig p226 40 cal and glock20 10mm. while cleaning them i noticed my sig had some pretty ugly burn marks under the slide. the weird thing is i shot the glock20 way more that day and she has no marks?

sig

sig

sig

glock

Looks like one of Sigs weird rainbow finishes to me...

 

ETA: seems as tho Sig doesn't offer the rainbow finish on 226s, so scratch that

It almost looks like case hardening but im doubtful that is the case. What cleaner/oil do you use? It might be the residue that was left after it got heated.

 

Im sure one of the resident sig gurus will chime in with a more definitive answer.

Glocks are just good like that... but really it could be the cleaner...

i went to the range over the weekend with with my sig p226 40 cal and glock 20 mm. while cleaning them i noticed my sig had some pretty ugly burn marks under the slide. the weird thing is i shot the glock20 way more that day and she has no marks?

Wow a Glock 20mm. Just busting. Yeah my fingers type faster than my brain too.

 

As to the sig, I've had sessions where I've fired a couple of hundred rounds and the slide barely got warm. So I highly doubt its heat discoloring the slide. I would think the barrel would be a mess if that much heat was transferred to the slide. Like previously stated what cleaner and lube did you use? Maybe its an oil and water rainbow effect.

As other have said it could be the cleaner your using, but to me it looks more like it was caused by heat, just the same way you will see exhaust pipes discolored on some motorcycles.

Heat discoloration, possibly enhanced by oil. Does not harm the actual metal.

I agree that it's heat and oil related.

 

I had a marathon shoot with one of my 226's and a few guys. 20 Mags and a 50 cal can of .40. 800 rounds one mag after the other. She was hot enough to feel the heat with our left thumbs and on teh front strap of the grip. Pretty hot but no damage.

outers is the brand, I'm glad that this is normal, I was a little worried that it was a close KABOOM! it's funny cause this is a new gun, my other guns don't exhibit this...