Hi! Nothing's hard if you understand it.
Yes, you can just run a ball expander through .284, TTL and then reload it! Make sure the brass is not brittle in the neck first, no? If it is, then you should anneal it first.
Dave, the 7.5 Swiss does not like all of the powders used in .308. Ball powders don't give anywhere near the accuracy of extruded powders like 4064, 4320, A4350, N160 and some IMRs like 3031.
Dad has spent over 40 years developing loads just for Swiss rifles. He has reams and reams of load data. The simple truth is that the original GP11 bullet of 175gr performs best in the 1911sr, k11sr, k31, zfk3155 and the PE57.
If you stop and think about it, the GP11 was developed by the Swiss just for those rifles.
Here are a few loads that will shoot moa or very close in any k31.
Sierra 168gr
46.8gr of H4350
Seat the bullet at 2.890
Berger VLD 168gr
47.4gr of IMR4320
Seat at 3.0425
I have lots more with the 175 bullets, but do notice that the seat depths are very important for these rifles. The VLD has a very long nose and the OGIVE is right near the case mouth, that's why the seat depth is what it is.
This is going to be fun!
:^)