With your hawkins rifle always keep in mind you have a medium twist of 1-48. If all you were going to shoot were roundball then a 1-60 or even slower twist is desired. If you were wanting to shoot sabots, then the 1-28 twist might be your best choice. Many people think 1-32 twist is the best for conicals. So you have an in between twist so to say. It is meant to shoot roundball and conical bullets. It will also shoot some sabots very well. It is all a matter of finding which one does best. My Hawkins will shoot roundball excellent. It will also shoot powerbelts very well. You just need to try them.

An oldrule of thumb is; the faster the twist the longer the bullet. So when you get the slow twist rifles, then a roundball or even a ball-et are good choices. In my .54 calibers I shoot R.E.A.L. conicals. They come in 300 & 380 grain. Both friends and I have found the 300 seem to shoot best in the 1-48 twist. For this reason, you might have wanted to look at the 360 grain (the shorter of the two). Although years ago I used to hunt with a 426 grain Buffalo Bullet Conical and had excellent results with 80 grains of powder. Also some tremendous down range thump. Some other projectile you might want to look into are Buffalo Ball-ets .. they come in 310 & 338 grain.