Hello, I am new to the forum. I live in Northwestern Metro Atlanta, getting into field target and hunting. I plan to go to Pyramid Air competition for the first time this year. I collect springers and vintage air guns. I have a HW35E 177 cal with a vortex spring. Last year I shot nearly one hole 3 shot groups at 15 yards. Now geting 1" - 1.5" groups with mixtures of clusters and vertical stringing with 5 kinds of pellets like JSB 10.34, H&N Field Trophy (4.50,4.51 and 4.52) and RWS match. None any good and hard to tell which one is best. Before this trouble, I did a dumb thing and overtightened the barrel pivot screw as tight as I good get it with a big screwdriver. I talked to Airguns of Arizona technician. They said the barrel pivolt screw should be just over tight like no more than 15 lbs torque or less. He was not sure on the manufacturer spec for that. I loosened it to 15lbs and then when down to 8 lbs. Some improvement on vertical stringing but groups still over 1 inch. Air guns of Arizona said my breach seal maybe bad but it looks Ok to me. Gun has about 250 round thru it so far. Tried 2 different scopes and same result. However it shoots good groups with iron sights. Have not dropped it, nor mishandled it and was always stored in case in a dehumidified room. I tried different artillery holds with no good results. Then shot my FWB 124D and RWS 350 and got excellent accuracy so do not think it is my shooting method. As stated, I shot it good last year. Another thing is when the problem started after the overtightening, I had to shim the scope as it shot like 3-4 inches low at 15 yard. Before it was zeroed at that range. I already have a UTG mount to correct barrel droop (10.1" I believe) from last year but still needed shims. Ready to send into Airguns of Arizona for repair. Thought I would post here first if any ideas to try. Also since airgun is out of warranty, if somebody knows a good reasonable place to send it instead of Airguns of Arizona.