If you have a 1/28 twist a bullet that is just under 2 calibers long is the closest match. That would be a 200gr 40cal in a 50/40 sabot or a 45 cal around 275 gr. quite often the 250 or 300 with shoot well with that twist I use 180 or 200 gr 45cal bullets when I want to shoot sabots in my 1/48 twist and 230gr [45]in my 1/38 twist. I have had to bed or relieve the stock on some Traditions so make sure that your stock has not warped and put pressure on the barrel. Lee