Brain
Frank Hollenbeck designed the "V" spring forend fastener seen on this gun. That feature/device was in production beginning with Frank's prototype, but had been entirely discontinued prior to serial number 8,000; and replaced by a "J" spring type fastener (Hollenbeck was long gone from the gun works when that change was made). It's a great feature as far as providing a very easy way to get a forend on and off a set of barrel, but it didn't serve to keep the forend tight against the knuckle of the frame; and, at least from my personal experience, it wasn't a stout enough spring and allowed the forend to occasionally spring loose on recoil. The SAC gun was improved when the "V" spring fastener was dropped.
