They are alike in that regard. Solids require more pressure to engrave with the rifling, so the start pressure is higher.
I used QuickLOAD's default case capacity with the TTSX, specifically (the longest of the 8 different 140 grain Barnes bullets shown), I show 100% case fill of IMR 4831 weighing 52.1 grains with the COL at 3.330". That matches Phoron's experience. If I swap in H4831, I get 52 grains being 94% case fill. If I swap in H4831 SC, 52 grains shows as just 90.4% case fill. But despite the higher bulk density of the H versions, it also predicts lower pressure and velocity at 100% fill for them than for the IMR version. That's due mainly to the IMR version having a much larger progressivity factor (steeper initial burn curve) that makes it burn more efficiently in this particular application.
What COL did you end up loading to?
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member