I also am using a 45/70 micro groove. Had a heck of a time working up a load with it but finally found one that works great...34 grns of IMR 4198 under the Lyman 457193 405 grn bullet using WW's. What I found, at least in my rifle was shoot a few rounds through too warm up the barrel and "foul it up a little." Afterwards they flew great downrange. This is a all day shooting load. I also use a Limbsaver recoil pad. I was really loading heavy for awhile but got tired of loosening my teeth. Don't know of too many critters that can walk away from the above load in N. America.

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You'll shoot your eye out kid