It was the lower. I changed the upper just because it was far easier. Fits nice and snug,pins are too tight to come out by hand,but a cartridge will do it. Ive been working the bolt with the handle,cycled it 400 times or more,so its ready for the first shot Ive got a lot comming up for the w/e,but I will see what I can do. At least I have my own range!