My Friend just got a tag to hunt a buffalo in southern Utah and cant decide if he wants to take it with his 338 win mag or use my marlin. In the event that he decides to us the round that god intended for buffalo what ammo choice would be the best? I have HSM 430g bear loads that use a meplat flat nose bullet at 1800fps.

That sounds like a decent choice. You want something hard and heavy, no expansion needed. Break the bones and penetrate, that is what you want. I doubt 500gr rounds will cycle. Handloading would be best to get the best accuracy/velocity recipe, but if not, then what you have or some of the Buffalo Bore choices would do the trick.

An actual hunt, or like the one my friend did. Ok you're shooting at the one on the left, painted #19, in red.

Its an actual hunt, one of the more difficult buffalo hunts in the US I believe

Well, whether it is a difficult hunt where you are stalking Bison "in the wild" or if it is a controlled hunt where you are told which animal(s) you can take; most of the modern .45-70 loads are very capable of taking buffalo (bison). The 500 gr Barnes FMJ-FN loaded by Buffalo Bore Ammunition is loaded to an overall length that will cycle in the Marlin 1895 and 1895G or 1895GS.
They also load a 405gr JFN and a 430gr Hard Cast. Any of these would be great for a Bison hunt/shoot.

Personally, I don't have any problem with shooting a bison just standing out in a pasture grazing whether it has a number painted on it or not. No worse than eating a steak from beef that was knocked in the head while standing single file in a packing plant.

Enjoy your hunt, I certainly would.

Thanks for the advice, I have talked him into using the 45-70 for he take down/ penetration power that it has as well as the quicker follow up shots as compared to the bolt action but we will take his 338 just in case we can not stalk in past 300 yards  ( We have heard they get spooked easily where we are going).  He tagged out for a female and one of the hardest parts of the hunt will be proper identification as it is a little harder to differentiate the sex's as compared to elk or deer.

Here's another ammo to look at.



http://www.garrettcartridges.com/4570.html

I've never run 500+ grain bullets in any of my 45-70 Marlins.  Don't even know if it is practical to do so.

As Elmer Keith often reported, the 500 grain .45 caliber bullets don't stop for anything.  Expect end-to-end penetration with ordinary velocity loads in the 45-70.  

I'd load the thing with black powder loads if it were my hunt.

I've fired the Garrett .44 magnum 310gr Hammerheads. They are a handful from my 7 1/2" Super Blackhawk but very accurate. The Garrett and Buffalo Bore ammunition is expensive but well worth the money when used on what could be a once in a lifetime hunt.

That is my dream hunt...not a boxed buffalo hunt but a real go out in the wild woods and pick your target hunt.  I'll never get the opportunity but it's at the top of dream hunt list.  There's only two dream hunts on my list to begin with, Alaskan moose and buffalo/bison...I am soooo jealous!!

That .45-70 is definitely the best choice...I would choose the following from Buffalo Bore in .45-70:

Item 8A 430 grain hard cast penetrator
Item 8C 350 grain JFN penetrator

I would kind of like to hunt buffalo with my 1873 Springfield "trapdoor" carbine .45-70.  It's an actual 1800's era .45-70 and very well could have been used back then to shoot a buff or two.  Sure it's limited to black powder ammo that is considered anemic by many shooters these days but these .45-70's and .50's of the era are what almost brought the species to extinction so the black powder .45-70's have proven their ability.  Obviously it would require a modified hunting strategy but bagging a buff with a black powder .45-70 from the 1800's would be the hunt of a millennium.

I would also carry my .50 Beowulf as a backup just in case conditions required an upgrade.  Nothing puts a buffalo down like a solid brass Spitzer .50 cal....

I shot one with a 338-06 and 250 Partitions. It died.

Either will work.

They are not hard to kill cleanly. I watched my wife pop one with a 30-06 not too long ago. I doubt anything bigger would have taken it any quicker.