I had a TC encore rifle and put the endeavor barrel on it. It liked 120 gr pyrodex RS and a 250 gr XTP CCI 209 primers. It shot around 1 MOA . The speed breech XT worked great and never had no problems. I loved the way it cleaned up. Pull the BP spray windex down the bore and then pull a .50 bore snake through and your done. I had an older TC with the threaded BP but the endeavor barrel made is so quick and simple. I hope this helps.