Hello I am planning on duplicating the orriginal military load, is there a preference between the Sierra 220 RN vs the Hornady  220 gn RN for reloading?

Buy one hundred of both, do testing, have good data collection, measure results and chose one.  Repeat process as needed.

Your gun will tell you which one it likes.

Same. Preference is determined by the individual rifle, along with all of your reloading techniques.

Also, many "reloaders", present company excluded, are not really good shooters to begin with and all of the potential determining factors are irrelevant because they can't shoot worth a damn.

So, do your work, play around with variables, and keep us informed. We always learn a little from everyone's experiences!

Thanks

Here's my $0.02:

The Hornady 220 gr RN is closer in dimensions to the original bullet, although it's not a FMJ.  The Sierra is a good bullet, but has a slightly different shape than the original.  Unfortunately, the only bullet that is almost exactly right is the Woodleigh, which is insanely expensive!

The bottom line is, as Whig and Culpeper have said, try them out and see which one your Krag likes better.  I have shot hundreds of both, and my Krag prefers the Hornady.  Others like the Sierra better.  Krags are practically human in their love of food (ammo). 

Here's my load:  Hornady 220 gr RN over 40.0 grains of IMR-4350 and a CCI #34 Mil-Spec primer.  I'm looking to possibly switch to using H4895, as the 4350 burns very slow, and I tend to have unburnt powder exiting the barrel.