More rookie questions...

Bolt - the exterior surface of the firing pin channel, where it slopes to the gas rings, is that normally kind of a rough surface?  or is that carbon build up?  If the latter, what's a good way to clean it?

Upper assy gas tube exterior - is it normal to get a little build up there?  If not, what's the best way to get it off?

Bolt Carrier Key - the Maryland website shows cleaning the interior with a worn brush.  I know about the drying it, pipe cleaner, etc and have seen those threads.  Do you guys clean the inside with a worn brush?  

Thanks in advance.

it's probably carbon & build-up. it'll happen after even one time of shooting. it's easier to coat it in some kind of solvent ( i use hoppe's 9, there's lots of types ) & let it sit for a few minutes, maybe while you're cleaning something else, then scrape it with something. I use an old brass pin punch, works pretty well, or a tiny flathead screwdriver. make sure the rest of the bolt is clean of course, including inside.

i haven't seen the outside of the gas tube get carbon buildup before, just a little discoloration. normally for me a little CLP rub ( with a q-tip ) will get any gunk off, but i read somewhere (sorry i can't remember) that you shouldn't try to scrape off the discoloration. the fitting is really close, it might have to do with the slight bulge near the tip & not damaging it. cleaning the inside of the key is necessary though, where the gas tube hits the carrier, & can be done with a q-tip & cleaner.

keep up your maintenance pretty regularly (i'd suggest after every shooting) & it'll be easier. it'll also keep you from having any kind of malfunction or problems for a long time. always have a good supply of CLP & a better cleaner, like the hoppe's 9. happy shooting