Carb spring collar mystery?

[T. Cotten]

Folks,
It is hard to imagine, but I think they were casting flaws.

Using a cheap 10X eyeloupe directly upon my camera lens, I was able to capture two shots of an M344 that just arrived today. Unfortunately, it had previously been blasted, so I prepped it the rest of the way.
Please note the resemblence to the dished M352 I posted earlier.
The next two attachments are cropped from those photos.

Note the grain in erosion1 appears to radiate from the bore.

Under 16x with a stereoscope, no 'chemical' pitting is apparent.

Although well scrubbed, erosion2 appears to show embedded micro glass beads?
I didn't think they made them that small.
The photo displays what could not be seen even with the stereoscope.

...Cotten

[T. Cotten]

Upon 32x inspection of the specks in my third photo above,
the particles are not embedded, opaque, but spherical and reflective.
I cannot identify them, but they survived hot soap and water, air pressure, and a cotton swab of carb cleaner to remove paint overspray!

Damn tiny whatever they are.

....Cotten

[T. Cotten]

Another perspective...

Folks,

Here's an M75 H-D LLinkert that exhibits similar dished erosion beyond a machined counter bore surface. The large well bore doesn't seem to make a difference, although the circumference seems quite uniformly rounded.
Inspite of the obvious wear mark, the spring collar retains its original nickel upon its bottom surface, making it a one-in-dozens, if not one-in-hundreds survivor.

Unfortunately, I cannot capture its beauty just right in a .jpg.

....Cotten

[Tommo]

Cotton,
I tried to send you a personal message but the system says your message box is full.
Can you please send me your contact e-mail so I can contact you.
Regards, Tommo.

[T. Cotten]

Tommo!

I can be best reached at liberty@npoint.net

Thanks!

...Cotten