TC Endeavor/ProHunter Speed Breech XT Breech PlugStainless Breech Plug for Thompson Center Arms Endeavor and Pro Hunter XT Muzzle Loader Barrels. This breech plug fits Thompson Center Arms 209x50 Encore Endeavor as well as the Pro Hunter XT muzzle loader barrels. Breech plugs can get crudded up and near impossible to clean after awhile... It's easier to just get a new one! Or, order a spare in case you lose your original breech plug. See accessories at our TC Muzzle Loader Accessories page.