Somebody posted asking about this the other day & I couldn't find the original post to reply to. I am really enjoying the TLR-2 Laser / Light combo on the HK45. It locks into the rail very easily and in exactly the right place, imo. Sighting it in was a breeze. Doesn't mess with my grip when firing the weapon although you 'weak hand index finger on front of trigger guard' guys may disagree.
It may look like the weaponlight is contacting the trigger guard but it isn't - that's the on / off switch (clockwise for momentary on & ccw for constant on). The little silver pin is the selector toggle for 'light only / laser only / both'.