Not an issue of COL, but length to the datum line that controls headspace. If your handloads chamber in another rifle, you might have a slightly longer chamber in that rifle. Your new rifle might be at the tight end of manufacturing tolerance, with a somewhat shorter chamber. Your reloading dies might be at the other end of the spectrum, or you might have them adjusted for another rifle. Try some factory ammunition, and you might check headspace on the rifle itself, although the odds of it having too little headspace are pretty remote.