Originally Posted by xsvdynastypballa
The correct way to do a barrel is to plug the back if its a two piece and ano the front with out a plug since it would leak through the ports anyway. The front on a two piece isn't part of the bore btw. For one pieces I like to plug the back and shove a plug down the barrel just passed the ports. In answer to your question yes it does change the bore of the barrel. A .68 will become a .69 and so on, Wonderboy is mostly right tho, It doesn't really change the finish MUCH. It will dull it a little depending on how may times its been stripped and reanoed.
.68 to .69 would be a .010" dimensional change. You probably ment .689" to .691"
Assuming you use a reputable anodizer the barrels internal surface texture should remain the same. If the barrel can't be plugged you will loose .001" per surface. This means a .689" bore will become a .691" bore.
If you plug a 1 peice barrel past the porting you will be left with a seam/ledge inside the barrel where the 2 anodizing layers meet. It may or may not affect performance depending on how well its done.