Ive opened up a few so far, so here goes.
Nitefinders are the best stock guns you will get, and mod fairly simply (although drilling out the AR can leave spikes in the plunger area, that need longnose pliers to get to)
Mavericks are crap to mod, stick with a nitefinder for sidearm.
Recon CS-6 are easy to get a cheap mod with, just roll some electrical tape around the front of the barrel where the spring goes (so the spring will end up against a solid wall of tape) dont make it too thick, its only got to stop the spring, too much will cause a jam.
Longshots are a powerful force to be reckoned with. The front part can just have the AR removed for a similar to stock nitefinder backup shot (decent for that suprise bullet), and the back can be done a few ways.
The way Ive done the back on my longshot is to use a washer under the pyramid shaped part of the plunger (the washer I use is actually this bent one that is like a keyboard key thick due to the bend thing in it)
This means your stock spring is more compressed at all times, increasing range.
And I havent even properly removed the AR from it yet lol (know how, too lazy to pull apart again just yet)
oh, if anyone has a few spare springs for any of the guns (stock or otherwise...) I would love to try them out.
And, I suppose if someone brings a precision screwdriver set and some electrical tape, I'll mod their recon for them. (you can drill out your own AR though)
edit: yeah, not going to be able to bring my longshot due to limited car space, and my nitefinder is lost somewhere under my bed so thats not coming either
(those are the 2 I own lol)