Check the custom fitting job I did on this case for my Mossberg Silver Reserve Sporting O/U.

I bought a Gander Mountain Guide Series case, then took out the 1st layer of egg crate foam and turned it over to put the flat side up. Then I broke down the shotgun and traced the outline of the parts into the foam and cut it out with my filet knife. I made cut outs for the stock, forearm, and barrels. Then I made 4 cutouts for chokes, earplug case, etc, and a smiley shaped cutout for my glasses with a v-notch in the middle for the nosepeice. There is a layer of foam below the cutouts but the top layer is about 2in thick so the cutouts are deeper than I liked, so at the barrels, forearm, and choke cutouts, I cut the scrap peice in half long ways and glued it in the cutout to bring the parts up higher so the top puts pressure on them when its closed. Once I had it all cut out & fit tight, I glued the large foam peice bumpy side down with Elmers & rubber cement to hold it into place. I think it turned out great! The peices fit nice & tight and it looks really cool! Looks all high class fashion to me!
