You are probably OK sticking with commercially available ammo.

The 40 is a high pressure cartidge loaded properly.

There is less margin of error than low pressure calibers.

Don't buy ammo because it's the baddest you can find.

If the 40 is any good at all, it's good with hum drum ammo.

If you want more, get a 45acp (a better caliber and low pressure to boot).

Just my opinion, of course.