The straps cannot be rearranged.
YES.... the straps can be rearranged. I just moved all 3 straps to fit my IWI gen 1 Ace pistol with a folding brace. All the straps are velcro mounted so they can be positioned wherever you need them.
This bag has apparently been re-designed since the picture was provided. Both the main interior straps and the 3 supplied AR-Type mag pouches can all be re-positioned. They are all Velcro mounts, with large Velcro areas inside the bag to attach them to.