Leave your rose shafts longer. For each inch over 28" you can subtract 5# of spine weight. So you start with a heavily spined shaft, say 60#, cut it to 30" and it's dynamic spine will be 50#. Add a 150gr point and get it down to 45#. The natural taper of many shoot shafts will allow for up to 10# of spine spread meaning it can be shootable from 45# to 55# with a shaft spineing 50#.