7.62 NATO in 308 Win.

Some shooters told me that the military 7.62 Nato fired in 308 Win. bolt action rifles are difficult to extract. As far as I know both rounds are identical and in many reloading manuals they are listed as such.

Is it possible that military 7.62 hardball are loaded to a higher pressure to cycle automatic weapons and machine guns, so the cases expand more than the commercial 308 when fired in the bolt action rifles, or that military weapons' chambers have more tolerance to make them digest the ammo at hand?

most military ammo is a bit higher pressure and sometimes a bit different dimensionally
then commercial ammo.

http://www.surplusrifle.com/ had a two parts article a while ago on that topic.