Make sure you select the model of the character, then the shotgun. And note that you cannot use Engie's shotgun on Scout, or (vice-versa) Scout's shotgun on Engie.

but thing is, its looking worst on engi s shotgun on engi s hand

Some weapons only work well using their respective animations, otherwise it'll look odd.

It's not a problem with bone merger. This same problem with the shotgun happens in SFM as well.

For weapons, it's best to manually pose them. Bone merge them if you're using the animated prop tool.

引用自 DryBoult：

When i attach a tf2 shotgun onto a tf2 character, the handle goes to the hand
IS THERE A FRICKIN SOLUTION OR WHAT!? I NEED AN ANSWER MAN!! :(

that happens but if you mean its in the hand then idk

Well you idiots exept Spooky One

You have to pose if the handle goes to hand Dont expect an animation

Pose them