Stretching your powder supply.

[DizzyJ]

Bullseye has always been my favorite for 9mm, 38spc, 45 ACP, etc.

A little goes a long way, and it works very well for these applications.

 

[Catfishmoon]

While I had not considered the benefit of saving powder, I prefer shooting reloaded 147 grain bullets over 124 and 115 (I usually use Xtreme bullets)... I found they are softer shooting in my pistol and just as accurate.