just going off of what they have posted on their site. they have bullet weights from 175 lehigh to 300 grainers and barrel lengths from 10.5" to 20". i am just repeating their info, definitely not the inside track on this. however it seems that you can use the heavier bullets with polymer tips and or heavier jackets and get positive expansion. after working with the 375 winchester, this looks like a viable 375 cal with higher pressures with recoil about the same as a 308ish.