Landngroove
I have a plain jane Triumph, it is a very good gun, mechaniclally and accurate. Mine is a 50 cal and when i got it was an un-ordinarily tight bore. I could not get anything down it.
As Grouse says clean the bore well. I could not believe the packing grease TC put in it. I think I am really fortunate that I did not shoot it before cleaning it.
Use a very good bore solvent as the barrel may be packed with a copper packing grease. These are the first patches out of mine...
I ended up running 100 strokes of JB's through my bore now I am able to load normal sabot bullet combinations including my favorite .459/300 grain bullets.