You limited yourself by buying a 45 vs a 50 cal.
You limited yourself even further by using pellets vs loose powder.
You limited yourself even-even further by purchasing a rock-bottom entry-level break action rifle.
45s are a fussier caliber & have less options on store shelves. Also, 1-32" to 1-38" twists are an optimum 45 cal twists for sabot/bullets. 1-20" to 1-24" 45 cal twists are optimum conical twists. That's why Knight went to a 1-32" twist with their 45s and White rifles rule the 45 cal world shooting heavy conicals in their 1-20" twists. There are exceptions to this because every bore is different in the same make, model & caliber. 1-28" 45s generally shoot your light sabots well, but a slightly slower twist shoot even better.
With new rifles of any price, I shoot a whole pack of cheap conicals first to smooth-out burrs in the bore & get my open & scope sights on paper. If I owned a new 45, I then would buy a popular sabot/bullet like Hornady XTPs 180 grain 40/45. I then would buy a 2nd bullet that's longer & pointier to try... like the T/C Shockwaves 40/45 200 grains. That gives you a variety.
I make sure my bore is dry (no oils or bore butter) before I shoot. Then I carefully adjust my powder load in five grain increments to narrow my groups (you can't do that with pellets).
If that don't work, I either slightly loosen or really tighten the stock to barrel bolt(s). Then I shoot again to check my groups. If that ain't satisfactory, I grab a flashlight & I check the stock fit to the barrel & fill in gaps with pieces of el-cheapo paper plates or fine-sand the uneven parts with sandpaper or file.
Inexpensive guns that are troublesome at first can become darn good shooters. I takes a lot of tinkering sometimes but the reward is special because you made that bullseye happen with brains, determination & experimentation.