So I shoot alot of shells through a lot of guns year round. I am an avid pattern tester so the other day I went to the range to pattern test the 3rd degree. I grabbed an 870 and put the Undertaker non ported choke in the gun and placed it in the same vice I have used for years. When I touched that trigger off...Holy Smokes...I thought it had broken my cheekbone. I thought well it might be the 3 1/2 so I shot two more 3" shells one that was HTL and the other was a lead load...the other two did the same thing don't know what the difference is but I won't be shooting that gun with turkey loads in it anytime soon. Maybe because I have gotten used to shooting ported chokes???