Strange Borescope Image

Wow, Spurred on by that I dug out my No9 Mk1 & My No7 LS bayonets, excavated my shadowless ring-light, a relic of my on CS & Forensics days, & took some macro pictures.

These are much lower mag, about 15~20X but its all my current camera will do.

Both show the "spiderwebs"although to the naked eye they look nice. These have been wiped & oiled & so on but no scrubbing, like a bore brush or J.B. paste, so they look dark, not bright. That reinforces the micro-rusting & scouring idea.

I guess its just a minute detail we never noticed till we had the high mag bore-scopes available.

The No7 Mk1, Rows of them, just above the lower groove .

The No9LS, a few, scattered just above the lower groove again & more on two "groups, just above the bottom edge of the blade.

I believe in this case, the "coating or plating" was a combination of carbon and copper fouling.  Moisture trapped under the fouling, or crept under it over many years of storage before I fully cleaned the barrel.  The corrosion does not show on the lands, because the bore cleaning that my Dad did before he put it away likely removed the fouling from the lands; it's the grooves that did not get fully cleaned.  

Filiform corrosion is typically cosmetic, does not usually go very deep like pitting can.  And, that's what it appears to be in this barrel.

I also see some of this on the Long Branch CMk4 barrel on the No. 4 T, which was stored in the same environment as the DCRA 7.62. 

So, keep barrels free of fouling, particularly if you intend to store the rifle for some period. 

After firing my No. 4 for the first time, I checked the bore with my borescope and saw these striations starting at the breach and extending about 1/2 inch toward the front of the bore. Any ideas? I also spotted some what might be copper residue in a few places. Will do some more cleaning.