Interesting tidbit. I recall participating in this debate on this site some time ago. Glad this source of information is online.
BRISTOL OR BRISTO? MYSTERY SOLVED – Geoff Fors HSN readers have wondered in past
issues why military manuals refer to the splined wrenches used in the R-390 series and most other military
gear as “Bristo” wrenches while other references call them “Bristol”. I did too, and finally found the
answer in the original manufacturer’s 1944 advertising. The design, intended to eliminate stripping
common with conventional ‘allen’ hex-key socket screws, was created by the Bristol Company, Mill
Supply Division, of Waterbury, Connecticut. Bristol called its unique product a “Bristo” multiple spline socket set screw, dropping the “L” off the end of the company name. So those military manuals aren’t really misprints after all; “Bristo” screws were made by Bristol, and either term is technically correct.
