I've been regaling you all with tales of my quest to produce truly match grade ammo for the 30-40 Krag.  To quickly recap:
a.  Match grade collet bushing resizing die with .332" collet (.002" neck tension)
b.  Brass trimmed to uniform length
c.  Primer hole reamed
d.  Necks cleaned inside and brass tumbled
e.  Brass full length resized with no more than .002" runout
f.  Powder charges all weighed to exactly 40 grains of IMR 4350
g.  Hornady 220 grain JRN seated to uniform length with final runout between 0 and .004".  By far the best results achieved to date.

I loaded 50 rounds of test ammo with 5 different primers:
a. Federal Large Rifle
b. Federal Large Rifle Magnum
c. Winchester Large Rifle
d. Winchester Large Rifle Magnum
e. CCI Large Rifle Magnum (250)

The results at 200 yards were startling:
a.  All the Magnum primers shot considerably higher on the target, about 12" higher, than the standard primer loads.
b.  Magnum primer groups were vertically strung as much as 10-12"
c.  Standard primer loads were approximately 3-4" in size and fairly concentric.  Using a 6 o'clock hold and a 300 yard setting the standard primer loads were clustered consistently around the X/10/9 rings.

The recoil of the Magnum primer loads was noticeably stiffer than with standard primers.

Based on the above I've decided to fore go any further testing of Magnum primers in my gun.  They undoubtedly work for those that recommended I try them, but for me they are not the answer.

The next test loads will be 20 each of the Winchester Large Rifle primer, the CCI 200, CCI BR-2 and the Federal GM Match primer.  20 rounds each should give me sufficient data to make a solid choice or two for testing a larger sample.