I'm working up some test loads for my new model 12F/TR 223 remington.
Really weird but the 77 gr. Sierra Matchkings have a COL of 2.260" and the 80 Sierra Mactchkings have
a COL of 2.550" That's a big difference. I thought maybe a misprint but not the case, I checked 3 different loading manuals and also looked on line all
say 2.550".

With the 80 grainers seated at 2.550 the bolt won't close all the way in my rifle, so I think I am going to seat them
until it closes with no marks on the bullet.

What do you think??
Bob