Everyone on the 500 list, take down your current attack point before blackwidow shotgun is given. Then do nothing until it's given and take down the new one. Definitely we need to consider the shot gun itself. So if your mafia is fully equipped with guns, find the used one with lowest attack. The difference can be deducted then.
Everyone can post it in this thread the attack points before/after the shotgun, the difference of attack points between replaced gun and the shotgun, and you level. It should be easy to figure out the SKILL POINTS effect if we have a large pool here.
PS: I mean skill points but I don't know how to change the title...
Here's a quick way to determine the attack points (AP) of the replaced gun: Attack someone and check the fight results. See the AP of the gun on the bottom. Definitely not all used guns are shown, so it's the maximum AP the replaced gun can have. You can take that as the result. Or you can be more exact, count the # of displayed used guns, and find the remaining used guns (# of remaining used guns = mafia size - # of displayed used guns) in your inventory.
But it does not need to be that accurate since 100 attack points is large enough to make a difference.