Yes you should be able to seat them a little deeper as is.
One way to extrapolate seating depth without data for the exact bullet is to measure the OAL for the hardball, then measure the length of the hardball slug itself, and the length of your bullet and subtract the difference in length. HP's are always shorter than the non-HP's.
Or you can seat them to Mag length as suggested. Do try them with a full Mag, good point.