I use IMR-4227 in the 30/30, I use 19 grains for 180 and 188 grain cast bullet loads. This load shoots exact same point of impact as 25 grains of IMR-3031 with the same bullets.
What Velocity you getting with your 19 grains?
If I remember right, I think it was 1775 with a Marlin 336 with a 24 inch barrel and 1675 with a Marlin 336 with a 20 inch barrel. It was a very accurate load for me.
The cast bullets I used were from a Lyman 311041 and a RCBS 30-180FN moulds. With the alloy I use, the 311041 bullets weigh 180 grains and the 30-180FN bullets weigh 188 grains. That is including Hornady gas checks.
