Only experience I have with N340 and .44 mag is with a 300 grain plated rainier. The loads worked...by that I mean they went bang...but were very lame, being slow and underpowered yet probably generating a lot of pressure. I think N340 is really not such a good powder for .44 mag. I have great results with AA#9 and H110. VVN110 is good also I believe if you're loyal to the brand