Ed, Nice gun. The case is not the correct factory case for the Straightline, but it probably protected the gun from handling scratches, etc. I'm not aware of any exploded views of the Straightline, but they may exist. I'm assuming yours chambers the .22 LR cartridge, as most of the Straight lines do after the first production runs, which have the 'Olympic" chambers, a carry over from the 3rd model Single Shots. A correct case for your gun would be the blue metal case with the tools held in by the spring clips. The design of the 4th model single shots ( Straightlines) came about after a survey by the Wessons of top match shooters asking them what they would like the 4th model to look like & do. Answers were varied, of course, such as "Make a single shot American or New Model #3" ( Custom gun makers of the 1920s era were producing .22 SS
by converting those early S&W revolvers.) I have a .22RF SS American in my collection. It's a masterpiece of gunsmithing, with a 9 in. barrel and resembles a Colt Camp Perry single shot, at first glance. as it has a flat cylinder. Roy Jinks said he had seen one other such gun, but we can't prove S&W made them as prototypes to test the idea. Single shot S&Ws are a fun category to research & collect - hint - look for factory shipped guns with smooth bores for .22RF shot cartridges. Yes, there are some and they will letter, if they are original. But also be aware that there have been a few "odd" guns in some auctions the last few years that have such things as zero prefix serial numbers and odd chambers, like .22WRF. Caveat Emptor - if it won't letter, don't pay big $$ ! Ed.