The 2017 Rawlings 5150 Senior League Baseball Bat: SL7534 is not legal in Minor B Little League division in 2017 as this bat has a 2 3/4" barrel diameter. Currently only 2 1/4" barrel diameter bats would be legal or the new USA stamped models; these are the bats that are required in 2018.
The 2017 Rawlings 5150 Senior League Baseball Bat (SL7534) will still be legal in USSSA tournaments and some other leagues. It will be illegal in Little League, Dixie Youth, and others. Here is a link with more information about it - http://blog.justbats.com/new-youth-baseball-bat-standard-usabat-effective-jan.-1-2018
Almost all bats are generally a touch heavier than their listed weight, anywhere from .2-1oz heavier. This is due to things like the grip tape and adhesives/glue being added after the manufacturer officially weighs the bat.