It started off as a CA M15A4 carbine,
then added the following parts,
Classic army SIR hand guard (UNC)
Classic Army flip up front sight (UNC)
Classic Army flip up rear sight (UNC)
Classic Army M15 special forces crane stock (jugglez)
G&P 2005 Knights Type Flashider (UNC)
6.03mm tight bore barrel (War Craft Games)
Guarder aluminum barrel (ASCA)
Guarder aluminum piston (bug)
Guarder aluminum piston head (bug)
Prometheus MS120 non-linear spring (204 Tactical)
ACTION Micro Visible Green Laser (WGC)
King Arms Red / Green Dot Sight with Quick Release Ring Mount (WGC)
Deans battery connectors (onlybatterypacks.com)
9.6v 4200MaH NIMH crane stock battery (onlybatterypacks.com)
I finally ended up with this,
Now according to Bug, when him and swatt13 put the mechbox together with the MS120 spring, they're pretty sure that its now shooting about 440fps.