I bought a #3 rebarreled by previous owner to 7-08. Octagonal bbl about 1-1/4 across flats. Forarm cut out for it and glued back onto it.

Under 1/2" group on first 5-shot group I shot with it.

Big barrel, lots of weight = very accurate.

Sorry I don't know the brand; but I've dealt with Lotar Walther - good folks, good barrels.