Ok, theoretically speaking how much of a difference would different cases make? I had loaded my original rounds with Winchester cases but that was all I had. I loaded another batch with Remington cases and my results were dismal at best. Nowhere near on target. I was wondering if it could be the cases. Here's the chrono results.
I didn't bother measuring the group. The group that was in the first picture I sent you was bottom right of the target. Today I was aiming for center bullseye of an identical target. I was hitting top row and 2 inches right. The group was over 2". The Winchester cases are ready to be reloaded, but today has me wondering.
The bullets were all cast at the same time. They are sorted by actual weight. These are in the 181.6-181.9 grains grouping. The Winchester cases were the ones that I had the stellar results with. I have those ready to load. Before I try anything else I'll try the Winchester cases but I'm wondering if my scope may not have taken a crap on me. It is an older Burris 3-9x40. Ever had that happen before?
If it was me I would clean your bore with Automotive chrome polish before shooting another group. Also 2" groups with cast bullets is an acceptable accuracy level for a hunting rifle. I've also found that holding the forearm when bench testing cast loads sometimes helps to tighten groups. Those bullets are moving slower but generally recoiling well because they are heavier. Just something to try.
Another thing to try is .5 gr of kapok fiber over the powder charge.