Why bullpups?

[Tony Williams]

I don't have data on the Grendel with the 139 grain bullet, but the factory load develops just over 2,600 fps with a 123 grain from a 24" barrel, at a relatively low pressure I believe (nothing like 60,000 psi). So if the Creedmore is c.2,550 fps from a 16" barrel with 139 grains, I presume that it will be in the region of 2,700 fps with the 123 grain (same muzzle energy). So a Grendel bullpup the same overall length as Creedmore carbine will lose c.100 fps in muzzle velocity, or around 4%.

Does this sound reasonable?