Fired bullets aren't a great way to check the bore diameter because they can shed a few thousandths depending what medium you shoot them into. Unless you can fire them straight up and catch them on the way down before they touch the ground.

To "slug" a bore you usually pound a soft lead slug or bullet through your bore and measure that. Use a hardwood dowell and a wooden mallet.
I have only measured 2 of these revolvers so I cannot say with any authority that all of them are .330". It's entirely possible you have a .326 bore. All the commercially available bullets 8mm lebel revolver bullets are .329" or .330" and I believe that is the original french bore diameter. But variations are certainly possible.