I just found this site also and this is my first post.
I have the Traditions Vortek UL and a Vortek pistol also.
I tried the pellets first then switched to pyro RS for more consistent loads. I got much better groups.
I got tired of having to clean the bore after every shot and switched to blackthorn 209. No more cleaning at the range and the breech plug doesn't get stuck, not to mention it loads very easy now.
I cast my own bullets and have tried conicals, sabots and round balls.
I have finally settled on a 450 grain cast lead .458 bullet in a Harvester crushed rib sabot. I use this in pistol and rifle.
The rifle shoots them minute of angle out to 150 yards. It might do well farther but have never tried it. I get 1557 fps at the muzzle with 90 grains of BH 209. I went up to 100 and groups opened up a bit and recoil was stout.
In the pistol I use 50 grains of BH209 and get about 900 fps. It shoots 2 inch groups at 50 yards. I guess I should add that I put a red dot sight on it.
I have put in excess of 400 rounds through the rifle with no malfunctions.
I know you will like your rifle as much as I like mine.
I drew a ML tag in NM and go hunting in a few weeks. I can't wait.