a like new bolt action knight disc .50 cal rifle that used a orange 209 primer holder was offered at a give away price of 75.00, after looking it over i ordered a pack of red full plastic jackets from knight and i took a carpet cutter and cut the small tube from the top of the jacket, leaving a full diamiter cylinder. i primed 6 with win 209 primers and loaded the rifle with 80 grs fff and a .452 250 gr bullet in a black sabot, all six fired with no problems(small amount of blow by). now i can fire the rifle untill the orange primer holders become available from knight again(they say they are going to make them again) the red primer modified holders seal the breech ok.