To add to the "Six Screw Discussion", I'll plead guilty to adding the term into our collector lexicon. I needed a quick way to help distinguish between the Transitional Model like the one Flap found and the Improved Model, which was the first I frame with a coil spring. At a glance, the earlier, leaf spring model had a visible strain screw to maintain tension, while the coil spring action did not have this "sixth screw". It's a kind of verbal shorthand, but becomes a baffling jargon to those who haven't been exposed to it. The idea behind it though is to distinguish between the variants at a quick glance.
Then again, my West Coast friend Hondo44 shares some of the blame. He accepted my use of the term and used it himself, then we were off and running, and among the I frame enthusiasts on this forum it fell into a steady usage. It has no meaning with the K, L, and N frames because the all have the strain screw anyway. This may be why the use of the term has stayed so close to the source.
Froggie
...Ben
