importing blender .fbx animation cause weird position and rotation

Hello i made some animations in blender and exported to .fbx but when i import them to unity some action clips have problem.

I have read similar situations (answers, community, stackoverflow, ...) i realized that blender and 3ds max are using constant animation FPS but unity has decimal values in FPS. and this makes problem for me.

FOR EXAMPLE i have shotgun reload animation that shell goes into weapon from frame 10 to 20 and from frame 20 to 29 it remains there and in frame 30 (just 1 frame) i reset position.but in unity from frame 29 to 30 takes about 0.05seconds and it shows that shell returns back.(i want to return immediately)

Ways have been tried

1. blender exporter settings (simplify = 0, sampling rate = 0.1, and any other part in settings)

2. unity (turn off resample curve, reduce keyframe, and lots of other settings)

3. unity (change time settings in project settings)

4. set interpolation mode to constant in blender

5. export 1 animation per file in blender

but none of these ways worked for me.please guide me.