i finally got around to trying to remove the barrel,i removed the gas tube and spring,now down to the big nut against the barrel lug,this one has a round nut with several holes in it about .25 inch deep,short of using a pipe wrench,what type of wrench do i need to remove a round nut?
thanks for anymore info,terry

You can make a spanner or for a simple alternative you can use a drift punch and a hammer. You have to go slow and be careful to not deform the nut but it can be done.