Wow this is a different kind of post. Most of the Accura owners brag on how well their rifles shoot and function. Its nice to see the other side of the coin. I do not have a modern rifle such as yours. Unless you call my Genesis that. I had heard of the breech plug issue from other posters. I agree with your that a better plug should have been included with the rifle but you must understand that is a little more market share they have their with making it an option.
I hope they get the rifle back to you ASAP. Then you can do more testing. Maybe some of the Accura owners can share their loads with you and help you to cut out some of the guess work.