A friend uses it in 30-06 with 168 Bergers. His daughter shot a very nice mule deer with it. Very accurate. He started using it in place of H4350 when the shortage started.
I've used 4451 extensively in 6.5creedmoor, hit a 1200y targets with it last October. I've launched mostly 140g but also 143eldx and 150smk with it. With the 140-143 range (seated long 2.825"-2.875") there is a flat spot between 41.5-42.2. also it likes CCI200 primers the best.