Tested a sample of D4198, that was gifted to me this weekend, in my AR (223 Wylde, 16" stainless barrel). Tested loads under a 55 grain Campro ranging from 17 grains to 21.5 grains in 0.5 grain increments. All the loads cycled the action without issues. There was minor flattening of the primers at 21.5 grains but no other pressure signs. I would feel comfortable going to higher loads, in smaller increments however.
At 100 yards, the POI rise from lowest to highest load was approximately 2".
POI of the 17 grain load was roughly the same as for my standard 55 grain bulk load with 25.1 grains of 4895. The recoil of 17 grain load felt like a 22LR. It will be interesting to see how this load performs in terms of accuracy and at longer ranges.
At 17 grains, the case was approximately 60% filled rising to about 80% of capacity at 21.5 grains. The D4198 also fed reasonably well through a Lee Perfect powder measure which I use for bulk loading of stick powders. Of 9 test drops one of them crunched some powder resulting in a drop of 24.6 grains. The other test drops were. 24.3, 24.2, 24.1, 24.1, 24.3, 24.3, 24.4 and 24.2.
I will be ordering some of the D4198 for IPSC rifle, CQB and training loads.