The FWC Handcannon has a unique perk on it called "Timed Payload". Its description reads "Projectiles attached to enemies explode after a short delay". This sounded very interesting at first but then in practice it's nothing but a less intuitive Explosive Payload. The delay is so short that it might as well not even be there. Unfortunately I don't have a Handcannon with Explosive Payload to compare it to, but comparing it to a Handcannon with similar impact (namely Bad News) it seems to increase damage done to the body but the difference in critical damage is negligible. The Blast Radius also seems rather small. Rarely ever hitting more than the initial target unless they have a very affectionate partner. These traits of course may be indicative of the regular ol' explosive rounds too. I wish I had the tools to test it. Bottom line "Timed Payload" seemed really interesting on paper but in reality it's just a re-hash of another perk.