Leave a 1/16" gap between the base of the bullet and Trail Boss. That will be safe and pretty slow. Depends on the twist for bullet weight; 1:16 & 1:14 for the 35 and 40 grain, 1:12 for the 45 and 1:10 for the 50. I have that bullet mold that uses a gas check, It does great in my old Savage 340, and not worth beans in the T/C 10"Contender or the Anschutz rifle (it is great in the 218 Bee No.! Ruger too!) Remember all modern 22 Hornets use .224" bullets, I size you cast bullets .224" also, not .225"!

Ivan