David

Has your Barrle lug been bedded yet?
Also I would go with a .505 bullet size and a .510A wad card from Track of the wolf I would also pick up some 777 2fg & 3fg and start with 75gr then go up in .5gr incriments.

I do not like a slip fit conical at all I like the rifleings to cut the bullet as it is loaded . And I found alot better Accuracy by useing a over the powder wad also.

I think you may be getting to much blowby as loose as your bullet is . plus not having the right fit on your bullet. Sounds like alot playing aginst you right now . If your stock is not bedded I would Deff. do that first.

Ron