You'll find data for these cartridges varies widely from a number of sources, probably because none of the loads have been pressure tested. There's an article in HANDLOADER #119 on the Improved with data. The same article was re-printed in Wolfe's "Wildcat Cartridges" Volume 2 (perhaps still available). HANDLOADER has published at least two other articles on the standard and/or improved versions, but I don't have the references on these, though they weren't recent.
As for a favorite load in the Improved version, mine was the Hornady 270 grain Spire Point and 56 grs. IMR 4064 for a muzzle velocity of 2340, very accurate.
Last edited by lotech; 10/11/22.
