I had a Winchester Model 70, Black Shadow, 30-06 and it took about 50. I tracked my groups and after about 50 rounds they got about as tight as they ever got. Out to 150 yards they could get from 1/2" to 1" depending on what factory ammo I grabbed. BUT after 150 yards it opened up like crazy. I shot about every factory round I could afford and nothing helped the opening up after 150. Never figured out why so I finally got rid of it. Not sure why either. It just bugged me I couldn't tighten it up after 150 yards.