Well, that leaves out command detonated mines. off route mines, or even the ADWS.
I haven’t seen any crossbows that can take out an engine block, ‘ cept maybe for one of these -
http://img.rlt.com/s/10501.jpg
I was thinking perhaps a silenced .50 cal. They make as much noise as an -06 but they do Git R Dun like only a .50 can do. So they key would be to remember the budget and cut down on all unnecessary expenditures -——— of lead that is.