Yukon:
That rifle will be simply wonderful in the hunting field. Proved for the 650gr bullet and the heavier BP load, it would make a marvellous 'nitro for black' big game rifle. Take a look at the Woodleigh 'Weldcore' RN soft with the thin jacket (for BP rifles), its a ripper!

Being a new poster here you may not have seen my opinion of the calibre, which everyone else is sick of hearing! (sorry fellas!)

Welcome to the forums BTW, and to the exclusive .577 club!

PS: W.J.Jeffery really knew how to put a nice hunting rifle together, and his makers were second to none IMHO. We had a long thread on Jeffery doubles a while back, if you're interested in some bedside reading!