I believe the reason they do not put a rail on the Sub's is because of their own Glock light. It is too big to fit and we all know Glock prides itself on interchangeability.
Gen4 G17, G19, G26. Love the Gen4's.
Glock and S&W M&P Certified Armorer
NRA certified RSO
NRA Instructor for pistol, rifle, shotgun & PPIH and PPOH