Wife says the barrel is at the house, and I am stuck 1,000 miles south of Hawaii for another two weeks. I did slug the bore just for fun when I got it, pushed a .177 pellet through it, and it was exactly .172. I went for a straight taper from in front of the forearm to the muzzel at .550 inch, hope it saves a little weight, may look a little odd, never know. I will shoot it as soon as I get back, should be a lot of fun. Got some 20gr bullets that should do about 4,400 fps out of it. Larry