Piper, may I suggest you take a look at the remington.com web site, click on ballistics and compare several cartridges to get a feel for what each one can do. do a google search on '30-40 krag for hunting'.
Also use wikipedia, search for 'rifle cartridges' and then follow the links to any cartridge you want to research. Lots of great info there including cartridge histories and specifications.
just put 'wiki 30-40 krag' in the URL line and you should get links directly into wikipedia for the Krag.
Another great place for info is surplusrifle.com. find US Krag on the list on the left and click on the link. Everything you want to know about assembly, disassembly, bolt removal etc. is there.
that said, the 30-40 Krag is slightly more powerful than a 30-30, but it is less powerful than a .308, both of which are common 30 caliber deer hunting cartridges. So yes, the cartridge is suitable for deer hunting, but you have to consider the gun too. What shape is the bore in? Any stock damage? What will it take to mount a scope? (if you want one). Do you want to modify a valuable original Krag and destroy its value? Maybe if you find a sporterized Krag it might be ok for hunting deer sized game but have it checked out by a gunsmith first and don't expect it to be a good investment. Lots to consider.
Last edited by bobvonb; 12-08-2009 at 12:58 PM.