As Parashooter stated, the lug failure is unlikely.  Additionally, there have been no reported cases of lug cracking or failure using the Remington factory ammo!!!  I've been shooting my 1898 WW1 veteran Krag in vintage matches for years using standard loads of 220 gr RN bullets with 40 grains of IMR 4350 and have yet to damage the action or bruise my shoulder. 

However, if you're still concerned about the lug, I refer to Michael Petrov's experiment where he machined off the lug, and fired a bevy of "HOT" ammo out of a Krag.  It took it all in stride.  What finally destroyed the gun was a load of 20 grains of Bullseye!  That kind of power would destroy just about any rifle! 

If you want to explore lighter loads, I suggest the 150 gr RN bullet for the 30-30 with a starting powder charge.  Consult your loading manual.