Carbon deposits around crown

[fullmetalredhead]

My DDM4 just passed the 1000 round mark and while cleaning/inspecting the gun I noticed a ring of hardened carbon deposit surrounding the crown. It's a pretty thick layer and I was not able to remove it with any of the cleaner or solvents that I own (Break Free, Hoppes#9, MPro7).

Here's a pic looking straight into the flash hider. Notice the crusty ring around the bore hole. It extends back to the walls of the flash hider. Is this normal?
http://i37.photobucket.com/albums/e85/vibrator1/crowndeposit.jpg

[bkb0000]

yep.. some guys pull the MD and clean it out, but the other 98% just ignore it. so long as the crown itself- the corner- is clear and sharp, you shouldn't have any noticable effect.

[Quib]

It's normal. And I’ve had decent luck cleaning it up with Break-Free Foam Bore Cleaner.

See my tutorial here:

http://https://www.m4carbine.net/showthread.php?t=35490 (https://www.m4carbine.net/showthread.php?t=35490)