I was trying to sort out a slug problem .My M4 loves h&n 218 and the new JTS slug that has no diameter size just .22 . I tried some of the new corbin slugs 28 gr & 34 gr both in 218 . My M4 and my amigos M4 did not care for them so much . The only visual diff was the corbin had a deeper dish base with shoulders where the other two were slight dish no shoulder. Just a dimple . I decided to measure 10 slugs of each of the three . 
The JTS were 8- 218 & 2-218.5 OK . The Corbin were all 217 . Then my favorite H&N 218s were one at 218 & 3- at 216.5 & 6 at 217. Any thoughts on this will be pondered greatly ! Thanks
The JTS were 8- 218 & 2-218.5 OK . The Corbin were all 217 . Then my favorite H&N 218s were one at 218 & 3- at 216.5 & 6 at 217. Any thoughts on this will be pondered greatly ! Thanks