Inch pattern receivers have been made intermittently (and of varying quality) by several American manufacturers.
DSA is probably the best known; their early
Australian
-pattern examples (made by a subcontractor called LMT) were of excellent quality, while their in-house examples (both Australian and
British
pattern) have been hit and miss.
Two now-defunct companies, Entreprise Arms of California and Coonan Arms of Minnesota, also made inch pattern receivers in the past. Outside of early Entreprise examples (also made by a subcontractor, also excellent), they tended to be problematic, ranging from "minor issues" to "blatantly unsafe".
IMBEL of
Brazil
(a legitimate FAL manufacturer) produced semi-automatic versions of metric Type 3 receivers for the US market in the 1980s. Century Arms had some of them cut to accept inch pattern mags for their "R1A1" rifles (assembled in
Canada
from a mixture of inch and metric parts), and some have machined the British-pattern profile cuts into those receivers. Many consider that the best option for building a proper-looking British rifle today,