K frame
S & W MOD 65 IS A STAINLESS K FRAME SAME AS MOD 10 AND 19 ETC
A "J" frame handgun refers to the Smith & Wesson small frame revolvers such as the model 36 and to any other handguns of that size (Taurus, for example, has a virtually identical revolver) which are build on the J size frame. S&W makes K, L, N, and X frame revolvers In ascending order of size.
Medium
I don't know about the size difference but, the early 50's chev truck frame is straight from front to back. The 80's frame drops several inches between the front and rear axle.
The S&W Model 64 is the Stainless Steel version of the "blued finished" Carbon Steel S&W Model 10 .38 special. Both revolvers are "K" frames. There are 5 frame sizes in the S&W revolver line up. The "J" frames are the smallest. The "K" frames are the medium service size. The "L" frame are a beefed up frame version of the "K" with a full barrel length ejector shroud. The "N" frame used to be S&W largest revolver frame. The "N" frame supports .357 Magnum, .41 Magnum, .44/40, .44 Special, .44 Magnum,and .45 Long Colt. The "X" Frame supports .460 S&W Magnum, and .500 S&W Magnum. Hope this helps with your question about S&W revolver frames.
N frame S&W Model number.
Charter Undercover .38 Special is equivalwent to the S&W J frame size.
Blued J frame vs Stainless Steel L frame J frame holds 5 L frame can hold 6 or more
No "current frame" will accomodate a '28 body without fabrication and modifications. The Chevy S series truck frames are popular for classic hot rods, they are about the right size and more than strong enough.
All Winchester model 12's are take-down designs. Winchester made a model 25 which is solid frame and very similar to the model 12.
It is a J frame, the smallest. It is standard carbon steel. Also called the "Chief's Special."