Hi, I am sewing a man's overcoat and just finished sewing in the sleeves. I used the flat or shirt style sleeves as I don't think I have the experience to attempt the set-in, gather type sleeve yet. The problem is that there seems to be a bunching under the arms as well it being to tight across the back with my arms raised. The coat is of a medium-weight corduroy, interlined, sleeves as well, with a medium-weight cotton fabric. I was wondering if this is the problem? As with a shirt say, there is not much fabric to bunch under the arm. Or is it something else? Is it even possible to make an overcoat with flat sewn sleeves? Thanks very much for any help.

John