5 Segment Booster too heavy
I am trying to replicate the different launch vehicle designs that used shuttle-derived SRBs as a first stage.
When I am trying to replicate the Ares-Family or Liberty with the 5-segment booster from RO, I am running into a problem: either I modify the amount of PBAN one the booster to achieve 126 seconds burn time but end up with a much too heavy booster (around 900 tons). Or I leave the RSRMV-Booster in its "Stock RO"-configuration at around 730 tons, but it only has a burntime of around 105 seconds.
Is the RSMRV-Performance in RO realistic? All sources I can find say that the 5 segment-booster is designed to burn for 126 seconds with a mass of around 730 tons. If not, how could I change that it eithers uses less PBAN or that the mass of the PBAN is lower?