I bought a used Remington 552 Speedmaster, this rifle jams all the time when the bullet a feeds the new round into the chamber, then I have to hold the action open and use dental picks to remove the round. I have tried Federal Eagles, Winchester Super X, Blazers, and Yellow jackets; I have had the best luck with Yellow Jackets, only jamming on about every 3rd round. I have the owners manual; I have taken the trigger mechanism out and removed the barrel and bolt and cleaned and oiled them. Can someone give me some pointers on what to do now?