I have settled on a load for my PS90 but haven't tried it in my pistol yet.
I wanted to start off my 5.7x28 loading session with a load that would mimic the SS197 factory load, so I opened up a box of 40gr Vmax and got out some Winchester small rifle primers.
I tried a few of the Accurate #7 loads, starting at the minimum load of 7gr and found the load was much hotter than factory, too hot in my opinion. I didn't wish to subject my new $1500 toy to the beating of a constant diet of of hot loads so I backed the load down to 6.5gr of AA#7. While it was a bit milder, the recoil was still much sharper than factory and it still seemed like a quite of bit of powder was being wasted in the form of excessive muzzle flash. I then decided to turn my focus to HS6 and work with that and see how it does.
Thanks to a member on another board, I found a load that used a maximum charge of 6.5gr of HS6 and to make a long story short, decided on to 6.3grs. I loaded up 5 of them and mixed them one factory, one reload and so forth. I found the recoil to be comparable between the loads and the point of impact to be about the same at 25yrds. I am happy with this load for now and hope to crony a few when the weather gets better.
I suggest if you give this load a try, use common sense , as none of this data has been tested by "official sources". I would start in the low 6's and do not exceed the max of 6.5. I used an OAL of 1.590 and small rifle primers.
Keith