Are 250r and 400ex a-arms the same?

[fastkid400]

I was wondering if they were interchangeble. I might have a project 250r and was thinking stock 400ex arms wood be easier to get.

[airheadedduner]

The R frame mounts are 1/16-1/8 inch wider. You will need to make spacers or just tighten the frame mounts till you pinch them down which I don't recomend because it will cause them to bind up some.