Only 50-60' on your NF with a handyman spring? Wow thats low. Put in a Double Shot spring and it will go 70'. Thats what I did to mine. Cool mods, by the way.
Ace 49 spring. Also, I don't know why but I'm not good with Nitefinders, arguably the easiest gun to mod too... I'll range test again when I back on Thursday or Friday. Then tell the results.
EDIT: By the way, Dayko, epoxy putty is like a rock when it sets. It's great stuff. I'm not sure if it will bond with Plumbers Goop though. I used it as a second adheasive, maybe you can try to peel the Plumbers Goop off? Either way, you should try the Plumbers Putty, it's extremely strong.