This last week has uncovered a bad reamer probably several bad reamers floating around. Large contract barrel makers are making barrels for many companies using the incorrect reamers. The case length of factory brass as made is 1.585 +- the wall in the chamber where the case mouth should stop should be 1.610(SAAMI) plus the cone angle of .016 for a total gap of .041. The bad reamer has a dimensional error which makes the gap another .013" longer for a gap of .038" plus the cone of .016" for a total gap of .054". The bullets must span that gap from the case mouth to the start of the freebore. The freebore as measured in the bad chambers is .045 longer than the SAAMI chambers meaning the bullets have an extra .045" jump to the lands. That is likely hurting the accuracy with the factory loaded VLDs that need to be set close to the lands.
The chamber will likely help those who plan to use lighter bullets in the 55-77gr range because they can seat them out further and gain powder capacity.
You can figure out if you have a longer than SAAMI freebore by sticking a .224 inspection pin into the chamber and relating the length to the rim of the case or everyone can load the 90gr smk out to where they touch the lands and compare that measurement with others of different brands of barrels.
SAAMI print below-
Attachment 52408