Wrong sized case, how to resize ?

[divingin]

302 to 304 will be fine. A bit more than necessary (generally .002 to .004"), but well within what a lot of shooters use (up to .008" or so.) Neck tension will be a little greater, so seating will take marginally more force, but it won't affect anything in any measurable way. Seating the bullet will expand the case mouth.

[baih777]

which press do you have ?

[CSACANNONEER]

Yes, it's 308 win for sure . It's just its my first time loading and a friend told me to keep the opening at .343 so the bullet is not forced in when seated? What size is the opening for your case after resize ?

Please, PLEASE, find someone else to teach you. I'm not sure why anyone would that you need a .343 diameter hole to properly seat a .308 projectile. That would be akin to throwing a hotdog down a hallway.

[sj810]

302 to 304 will be fine. A bit more than necessary (generally .002 to .004"), but well within what a lot of shooters use (up to .008" or so.) Neck tension will be a little greater, so seating will take marginally more force, but it won't affect anything in any measurable way. Seating the bullet will expand the case mouth.

I appreciate the input, trying to get familiar with reloading more so I can have a better understanding when I take my reloading class at angeles next month .

[kcheung2]

Well it's good that you're taking the reloading class. Don't overthink things. Many of those dimensional requirements (except trimming) take care of themselves in a single pull of the lever. I suspect after the class you'll look back on these questions & have a good chuckle.

[LynnJr]

Your friend is correct but most here simply don't understand what he is telling you.
If your neck inside diameter is 0.304 and your necks are 0.016 inches thick your outside diameter will be 0.304+0.016+0.016= 0.336 on the outside.
Common neck diameters for those turning necks on 30 caliber brass are 0.330. 0.334 and 0.336 inches.
In your example if your inside diameter was 0.306 and your necks are not turned your outside dimension would be 0.338 inches.
To change necks that are too small you would run what is called an Expandiron made by K-M Tool into the brass.
If your loading flatbased bullets and you stay with an overly tight neck you will either peel material off of the bullets or collapse case necks.