5 gr of 777 is enough to tell. 777 has more in common with smokeless than it does with blackpowder. The difference between volume charges and weighed charges with it is very noticable. That difference increases the further the range. I've had loads measured out volumetrically that didn't meet my minimum accuracy requirements (2"@100 yds) that the same charge weighedto within 1/10th gr easily did. I've seen weighed charges 1/2 group size. When I weighed out 100 gr charges I found differences of 2-4 gr by weight. Some of my powdermeasures were more accurate than others.

I used to know a fellow over on the old CVA forum, underclocked will probably remember him, who weighed everything, bullets, primers, powder and sabots. He grouped them with no more than 1/10th gr differences. He routinely shot 1/2" groups and often 1/4". What always got me was he was so humble about it. I wonder whatever happened to him.