ok, with an accurate rifle 400 is easy
can you shoot more and cheaper, that's a moot point, what your wanting to do is cut costs so you can shoot enough to become proficient, you will not save money unless you figure it per shot, but you will always have ammo and your shooting will improve.
can you improve the performance of a 270? well you can tailor a load to suit your rifle and it will shoot better. I haven't bought a factory centerfire round since 1981 with the exception of 223, that's cause I own 5 of them and won't take time to reload for 2 AR's and a mini-14.
RR