Given some 25-06 Nosler ammunition

[hrd2fnd]

I was presented with 57 Nosler rounds in which I have no need for. As the labeling on the plastic holder states the following.
 
25-06
Nosler Balco
1MR4831
3400
Casings shows stamped DEN 42

Now I can guess the 3400 means fps, but no idea about 1MR4831.
There is also 20 rounds 25-06 117 grains factory primer in Rem FC casings. Can I assume these are reloads? 

[jackelope]

IMR4831 is the powder.

[bobcat]

I don't know what the "Balco" is. I guess it's the type of bullet, which obviously is made by Nosler, but I haven't heard of Balco.   

The headstamp on the cases "DEN 42," my guess is that they are military 30/06 cases, probably made in Denver in 1942.

[Fl0und3rz]

Surplus 06 brass. Denver ordnance. 1942.

[hrd2fnd]

Thank you gentlemen