Going to try to make a long story short here: Had what was apparently a dumbass idea to make a diy boresnake out of paracord, figured tying a small knot in it would be the perfect size to pull though the barrel. Well it got stuck in the chamber and after exhausting all attempts to get it out, tried a suggestion of disassembling barrel and screwing in a drill bit by hand into the paracord through the chamber and pulling it out that way. it worked, but the drill bit left a deep scratch about 1/4 inch long on the chamber wall. Tried dropping a round in, hard to tell if its seating all the way. Is the barrel fucked or is it a possibility to sand it smooth?

I would suggest getting some polishing compound and polish the chamber with a chamber brush dipped in the compound. I usually hook the brush on a piece of rifle rod that is screwed into a hand drill. Go slow and steady The brush will hold the compound enough to polish the metal, but will not remove metal.

The only way you will know if your chamber is ruined is to reassemble the gun, and test it to see if it loads and ejects properly.  If it does that then you might want to test fire it.  See if it feeds and functions fine, and inspect your brass to see what it looks like after firing.   If it works okay and your brass looks okay then just keep shooting.

If you are at all concerned about the condition of the barrel, then just buy a replacement.  There are places selling barrels now.  They have them on EBAY for about $100  and up. Do a search for 5.56 barrels.

I can't even imagine why you had to drill it out.

Shoot it and stop fucking with shit.

I'd at least try it as is. If you do get failure to extract, don't use more power tools. I'd try a gunsmith that has a chamber reamer and see how much of the scratch could be removed w/o making the headspace too large, which will lead to split cases.

If that doesn't do it, it's new barrel time.

AJ

This.

Personally I would do this. And for future reference don't take anything abrasive to your chamber, ESPECIALLY something that's made to drill through metal

Do you have a fired shell? If so, load it. Hit the Forward Assist to see if the bolt is locked. Pull charging handle and extract it. If all that worked, the next step is to load a live round and extract it. At this point I would go ahead and fire one round. Examine the shell to see if any mark transferred to it from the gouge. If nothing there, use the gun normally.

So you thought that was a better idea than letting a armorer have a crack at it?    If a smith messed it up at least you could have him replace the barrel...providing he agreed to do it.

I'd shoot that barrel in a heartbeat. But then, I'm not the sharpest knife in the drawer. I've seen worse, WAY worse with no ill effects.

As other's have said, I'd second the: shoot the dang thing and quit sweating stuff like that.