When Bullseye was the dominant sport, a lot of serious shooters had their K 38s rebarreled with Colt Officers' Model Match barrels. S&W barrels had a twist of something like one turn in 18 1/4 inches, which had 148 gr wadcutters teetering on the edge of instability at 50 yards. Somtimes you could see a little tail on the bullet hole. I think one of Gil Hebard's catalogs had an article about this. The Colt barrels had a twist of one turn in 14 inches which gave adequate stability. I ran into that myself. I had a 8 3/8 inch barreled K 38 which I used for silhouetta shooting. I loaded up some wadcutters and tried them. At 25 and 50 yards there was no problem. At 75 yards they were all over the target and at 100 yards most of them weren't even on the backstop.