I use 7828 in mine from 5 deg F to over 90 deg. I have had very consistant groups. And no pressure spikes. But my gun is not yoursThanks for the info. I have read 7828 is temperamental so I was a little concerned. I will try Retumbo and H1000. Berger stated the fill ratio to be 104.7% for Retumbo and 100.1% for H1000 with Quick Load data. I would like to stay away from compressed loads as I have had issues with them in the past.