Chaos -
My records show a 6.5-55 AI that was in for restoration several years ago. The semi-heavy barrel had been 26", was re-chambered down to 24 3/4" and crowned 10 degrees (rounded dome).
The trigger was re-polished and adjusted to customer's preferred 3.25 lbs. pull.
Considerable stock restoration left it in questionable shape, a new stock was suggested, but not purchased.
Barrel and action were de-rusted, welded, filed, shot blasted, normalized, cryogenic treated, straightened, and Parkerized.
An accurizing effort lists 15-round groups average .72" at 300 meters with max group at 1.48". A 5-round group at 500 m was 2.54", a 5-round group at 800 m was 7.44", a 5-round group at 1,000 m was 12.14". Accurizing was done with new brass, slugs were 125 grain Sierra boat tail spitzer. I see several tests with conflicting data regarding powders and charges. Probably mis-recorded or should have been re-run. This was NOT one of Parker Ackley's jobs - its not his handwriting - probably either my grandfather's or one of his friends, possibly one of my uncle's. Nobody signed the notebook.
Note on the .260 Remington round - a friend made up a .260 and quite stoically reported it as one of the best 1000 m rounds available - that was before he tried the 6.5-.284 (now Norma) round, which he reports is THE best. Other friends are split regarding the 6BR and the 6.5-.284 Norma - groups keep going down as they put their money and efforts into these 2 excellent rounds.