Searching for a pistol/grenades-build
Other then bleeds you won’t get much from the Rifle so I can’t imagine it would work well. Most of the time people use Rifle in WvW or PvP to use the CC.
Rifles scale better with power and obviously dont offer much in terms of conditions but if your going to use GK as your primary damage source and swap to rifle for CC etc then it would be fine. You will be missing out on a second sigil though.
I have a build I use (not mine originally) which focuses on power-based damage with grenades instead of condition damage. It’s sort of how 100nades used to work, although this was not a 100nades build since it doesn’t use kit refinement.
Build: http://en.gw2skills.net/editor/?fcAQFAUlspSXHxSfF17ICoC5loHPGlNZfeMfPIEC-ToAg0CtI0RljLHjOygsBNo4QB
It can be configured to personal taste, particularly in the areas of sigils, runes, and explosives line traits (i.e. sigil of battle instead of air, runes of the scholar instead of might stackers, explosive powder and short fuse instead of enhance performance and empowering adrenaline). I find the rifle can actually hit quite hard with this, so I don’t like to dump absolutely all the damage into grenades.
I’ve run this fairly often in sPvP and it’s one of my go-to builds for tPvP play, although I don’t feel it’s the most viable in terms of competitiveness. I’m not sure how it would hold up in WvW though.