Well I got what I think is the final bushing installed in the Rem bolt and headed to the farm. I have been searching for the correct thickness of bushing to allow smooth loading for all of the different primers + allow for a near blow back free breech area after shooting multiple shots.
Today I shot 26 shots at the farm and I am very happy with the results of the testing. The breech area remained relatively clean and free of debris... the target was not great - I think i was having one of those days, but I was shooting a combination different bullets, different sabots, and different primers.
The bushing that is in the bolt now does apply pressure to the longer primers and does fit the shorter primers very well.
Here is a picture of the breech area after shooting this morning.
Here is the target with the velocites from this mornings activities... The grouping is not great and I think this gun will shoot far better than the target shows. I did not track the hit locations so there really is not much use for the target other than the velocites for those that might be interested....