Weight w/Mag: 42.2 oz Item Number: E26R-9-SSE
Caliber: 9mm
Action Type: DA/SA
Trigger Pull DA: 10.0 lbs
Trigger Pull SA: 4.4 lbs
Overall Length: 7.7 in
Overall Height: 5.5 in
Overall Width: 1.5 in
Barrel Length: 4.4 in
Sight Radius: 6.3 in
Weight w/Mag: 42.2 oz
Mag Capacity: 15 Rounds
Sights: SIGLITE® Night Sights
Grips: Custom Rosewood Grips
Frame Finish: Stainless
Slide Finish: Stainless
Accessory Rail: Yes
Features: SRT™ - Short Reset Trigger

Part 2 yes the 45 is listed as lighter at 39.1 oz (from multiple sources) (maybe the weighed it without a mag and the P226 is with mag ) SPECIFICATIONS:
Mfg Item Num: 220R45SSE
Category: PISTOLS
Type :Pistol
Action :Single/Double
Caliber :45 Automatic Colt Pistol (ACP)
Barrel Length :4.4 in
Capacity :8+1
Safety :4 Point
Grips :Rosewood
Sights :Siglite Night
Weight :39.1 oz
Frame Finish :Stainless
Frame Material :Stainless Steel
Barrel Type :
Slide Description :Stainless Steel
Case Type :Hard Plastic

Regan, Sig's stated weight for this Pistol's Overall Weight is 42.2oz.