Trailboss works well, but it has a poor "bang for the buck". It'll take around twice as much as Bullseye to achieve the same velocity. It's claim to fame is its bulkiness which allows for easier spotting of double charges. Your choice, but I stick with the Bullseye. Example, as taken from the Lyman manual, .30-30: 150 grain bullet, 8gr. Trailboss=1140fps/31,600 pressure. Same bullet, 7gr.Unique= 1200fps/24,200 pressure. TB isn't efficient and it can be spiky in pressure. (The book doesn't list Bullseye for the .30-30, but as a comparison in the .45ACP, in a waaaay smaller capacity case, shooting a 200 grain cast bullet, 4.9 grains yields only 12,900 c.u.p. pressure and pushes it at 840 fps- out of a 5" barrel.)
Darned good advise re: the Lyman cast bullet manual. My apologies for not mentioning that.
