Is the bullet nose contacting the rifling and preventing you from seating the cartridge? I size the noses of my RCBS 145 and 168 cast bullets with a .277 H&I and they slide right in. Another thing to check is how you are adjusting your FL sizing die. If you are just setting the die to touch the shell holder you should lower the ram a little and screw the FL die down another 1/8 to 1/4 turn to take all the slack out of your press. That might just bump the shoulder back enough to allow the cartridge to fully enter the chamber. Also some shell holders are thicker than others and I have found the Lyman shell holders give you a couple more thousands of sizing. Lee shell holders seem to be the thickest. At one time Redding used to offer shell holders of different thicknesses to aid in FL sizing. I have used 23.0 grains of AA5744 in my 260 and 308 Strikers and it has proven to be very accurate with the 145 and 168 CBs. Also used the same charge in a Wichita silhouette pistol in 7mm International which is about the same case capacity as the 7-08.