Sounds like they may not be selling as expected. Macks already had the cheapest price on them. Makes you wonder. I am with Tuck on this one BC and HV. The BC's pattern so good in my gun.
I would pattern the gun and see where it shoots and then I would use the shims to adjust. I like the trigger job idea but I would not port the barrel. The ports make the gun loud in the blind and are a pain to clean. Hope this helps.
Yes I shoot a SBE2. I had similar results with this same choke and BB's. Also make sure you shoot a big piece of paper(4x6) so you can tell where the pattern is. I once had a SBE1 that shot so high I thought the pattern was poor but really it just wasn't on the paper. My SBE2 shoot high as well. I switched to the "c" and it's fixed it. Hope this helps.
Here is a pic of my pattern with Black Cloud #2 3.5" at 40 yds with a Briley standard extended non ported choke. I tried all the BC chokes from Briley and Carlson as well as about 10 different other chokes and constrictions, but the Briley LM did the best. 30 inch circle by the way
Mine has not as of yet, but I only have about 2000 rounds thru it. I would say it is pretty normal. Anytime you have parts sliding(fricition) across one another overtime something has to give. Just as long as it doesn't come off the outside.
I have taken them apart. There is also a chart on duckhuntingchat.com in the reloading section that has a chart. #2 steel shot in 1 1/4 oz which is what the 3" shell is has approx 155 pellets. 1 1/2 oz (3 1/2" shell) has approx 186.