hello,
If your theme width is set to fluid then the width will always change depending on your screen width, there is no way to tell a width for the slider like that, thats the reason the slider must handle the image responsiveness by cutting edges or zooming ...etc to fit in its container
but i would say that 1000x300px is too small, set it to 1920x300 at least, becasue 1920 is most common screen width
The slider dimensions on mobiles and tablets is set to auto, it will automatically adapt depending on the slider contents and not the images
Dreadnought is designed to be a boxed layout theme, using the full width option on the swiper slider app with themes like Dreadnought is messy, its only good for themes like the default IPS theme
In the swiper slider app use the auto width in so it adapts to your theme width
and if you have issues with the application please use the swiper slider support topic