I Couldn't find any chokes in stock that i really wanted for my 410.. so I made my own.. a .390" that is about 1/2" longer than most extended chokes. This has a longer(smoother) Internal taper, as well as a longer parallel section as the shot exits.. Hoping for more even and consistent patterns vs the industry leading chokes..
Second choke is in the works, starting tight and going to open it up .002/.003" after each shot and document.. I also have several handload recipes to sling through it. I'm quite interested in experimenting with this one.