Cause its probably from irg. There will be a mix of 2015-2016 coming in from the distributors and all 2016 and on will have the welded pack.
For an extra 20$ for the drill and screw, i am just gonna buy it just in case, pretty pointless and useless as is when i have the trigger and spring but cant put it in. Woest part is i already have the trigger and spring but the gun is nowhere close to wolverine's door step. Hell, it probably havent even left the factory yet