Continental O-470 Piston Wear

[robertb]

Hello gang,
I have a question regarding interesting piston wear. I had a cylinder removed recently for an unrelated issue. An overhauled cylinder is now installed and the removed unit is likely headed to an engine shop soon. But before it heads out, I took a look at it and found something a bit odd. I haven't had a chance to query my mechanic on it yet so I thought I'd see what opinions exist here.
The sides of the piston near the top have, what I as a layman, considerable wear. How "normal" is this to you all based on the attached photos?

As always, thoughts and comments are appreciated.

 

[GeorgeC]

previously:
www.pilotsofamerica.com/community/threads/black-carbon-coated-pistons-only-18-hours-use.152082

 

[Bell206]

As always, thoughts and comments are appreciated.

Are those marks in the deposits or in the piston itself?
Were there any corresponding marks in the cylinder wall?

 

[robertb]

Thanks guys! I will take a look later today and see. My brain automatically thought there were groves in the piston itself. I'll check and see if that is just groves in carbon and gunk build-up. The cylinder has about 1,600 hours since major o/h based on the logbooks. I can see a similar pattern of wear at the very top of the cylinder wall. It is visible to the eye not not touch.

 

[robin ardoin]

Like @Bell206 implies, a couple of photos suggest excoriations in the deposits as there are a couple of bare metal areas that look unaffected. Take a fingernail or a hard plastic scraper and remove some of the deposits.