I would also like to know what rifle you are shooting. Hopefully not an Omega, which won't reliably shoot conicals. If not, then you may just have to monkey with other bullets and other powders and see what your gun likes. It can be a somewhat long process. Pyrodex is usually an accurate powder, so I would not change that first. Changing the bullet and possibly to another primer might make a difference. If it is an Omega (or any other Thompson center gun with a QLA), then you are probably locked in to trying powerbelts.