Jack Seehase was some kind of a NASA Phd engineer and a trap shooter. I forget his actual job and employer as I am doing this from foggy Monday memory. But he was a force that commanded attention about 20 some years ago. He put out a brochure that talked about porting, chokes, barrel vibrations and much more. I do not suggest he had all the answers, but he makes for interesting reading for us shooter junkies. In fact any shooter of shotguns. The pics below are jpg scans and hard to read. I have his brochure in a zip file and will be happy to forward it to any one that sends me an email request. Adn for those of you that have something to add about Seehase or his shotgun work, feel free to comment below. As always I take no offense to what ever you want to say about shooting on a post other than dumb stuff.