Extraction problems with Kimber .223

[laloremus]

I just acquire a Kimber Super America .223 it was never fired before. I shoot Winchester USA 55 grain 5.56 mm. ammo yesterday.
The first shoot the case was dificult to extract, the second the bolt moves up, but not backward, I need a blow with a piece of wood to open the bolt.

I don´t know if the ammo is to hot, the case don´t show signs of excesive pressure in the primers. What I notice is that the bolt is a little hard to open even without firing. A friend examine the bolt and tell me that I just need to polish one side of the bolt lugs that show signs of pressure or friction. Since I live in México and we don´t have good gunsmiths around, I ´can do the work myself with arkansas stone, but I don´t know if the problem will be solved with that action or if it will be dangerous to the rifle and shooter.

Any advice will be welcome.

Thanks.

 

[Bartholomew Roberts]

5.56mm ammo has a longer leade than .223 ammo. If you are using ammo labeled 5.56mm in a .223 SAAMI chamber, you may experience the problem you are describing, particularly with a tight .223 match chamber for accuracy.

I would try using ammo marked .223 in the rifle first before you polish anything.