I have a 649 no dash and my carry ammo is always the 158 Nyclad +P. Rated for it or not I don't expect it to fire any more than 10 of them in it's life and it has already gone through 5. I know where they hit so there isn't much need to run a steady diet of +P through it, besides they aren't much fun, but more fun than +P in the + rated 442.
Carry the nuclear rounds practice with conventional ammo and you will never have a problem.