sabotloader

My first question would be - do you need the Crush Rib sabot? If the bore is not that tight and in a Black Diamond it should not be but that does not mean it isn't, I would really try a different sabot. Older Crush ribs can leak pressure around the outside unless they are crushed tight. I would bet you would have better accuracy with a standard black Harvester, either the sort black or the long black. The other option is the MMP HPH-24 which comes standard with TC bullets.

One other thing I think that Harvester has changed the design of the crush rib sabot to help it retain pressure by putting the ribs on in a diagonal patern vs the normal striaght up and down pattern. The diagonal pattern would help the sabot seat in the lands and grooves better IMO.

Do you have any smooth sabots.... if you do maybe remove your BP and push a couple down through and see what you think...

One other thing check your barrel to stock channel - is the barrel getting caught in the channel in anyway....

I shoot most often 110 grains in a simular gun but I do use a different and a bit longer bullet most often.