AR-15 buffer question

[Clockwerk]

I purchased a custom built AR-15 and its brand new (the guy never shot it) but when I push out the rear take down pin and swivel it down i noticed scratches on the buffer itself and when I swivel it down to close it the upper scratch's the buffer any ideas as to what may be causing this? Never encountered this before but I'm guessing the tube is too forward?

 

[mc223]

Sounds like it is set perfectly. Use a Scotch-Brite or similar on the back end of the carrier till it is smooth and burr free. The scratching will cease.

 

[madcratebuilder]

The back of the bolt carrier should just touch the buffer when you close the upper. If you are getting marks on the buffer there is a burr on the back of the carrier. Deburr it and you should be gtg.

 

[Clockwerk]

It scratches it pretty badly though and do you have any suggestions as to what tools I should use to debur? I wouldn't want to take off too much haha and would it be bad if I re-polished the buffer?