Looks to be a late 50's build at the earliest as the 280 Remington came out in '57. I have a couple stockmakers in mind that might have built it as well as an idea on who put together the metal. Who do you guys think might be responsible for this nice looking rifle?
https://www.gunbroker.com/item/785910991

Whoever stocked it must have admired the work of Thomas Shelhamer. It's not in every detail, but the influence is pretty clear. No notion at all as to the metalsmith.

Who was making half octagon barrels with full length ribs in the 60’s?

Before my time but I believe you could order them through Flaig's etc. from Germany or Austria.

From a 12/1956 GUNS Magazine, Flaig's adv:

BARRELS
BOEHLER BARRELS, proof steel, semi-octagon, ribbed,
matted entire length. Mode by FRANZ SODIA of
Ferlach Austria in .35 .270 7mm .30 8mm and
.375. 26" Highly accurate-in the white, $45.00.
(Fitted to your action, with sheard bead, complete
price $60.00)
New Springfield 4-groove barrels.. ........... $13.00
FRANZ SODIA Boehler proof steel barrels 24"
gradual taper. About 2 1/2 Ibs.; highly accurate 1-10
twist, caliber 25, .270, 7mm or .30 $30.00.
(Fitted to your action, headspaced and
test fired, $10.00 more).


http://gunsmagazine.com/1956issues/G1256.pdf

Fun read if nothing else...I find the ads interesting.
Maybe I'll order out one of the Boys A/T rifles for $79.95