MikeP - well buddy, you have managed to hit upon a favorite topic of mine, the 200 gn 38 spl loads.
You are correct about the ballistics of the 38/200, slow as it was at only about 600'/sec from a 4" bbl, but very effective. The Brits replaced their old 455 Webleys with the 38/200 as it produced the same battle field effectiveness as the 455. That slow moving bullet didn't tumble when it hit, it was a round nosed slug and penetrated clean through in many instances. In others. the bullet would hit bone and deform, as it was made of soft lead, and would cause non-healing wounds which differed greatly from the jacketed bullet woulds of other calibers. Hence, the 3rd Reich complained about that bullet at the Hague Convention and as a result the bullet weight was dropped to 178 grains where it became nearly ineffective.
Col. Charles Askins once reported that he had shot a German soldier at a distance of about 25 yds as the man turned and jumped over a fence, with a 38/200 - Askins reported the bullet struck the soldier in his backpack and course completely through the body, killing him. Later, after the war was over, Askins was reported to have used/preferred only two calibers, the 45 automatic and the 38 Spl using 200 gn bullets, and he used the 38 spl with that 200 grain bullet a lot.
The 38 Spl with a 200 gn bullet was faster, by almost 200'/sec than the 38/200 which was based on the 38 S&W case, as shorter and fatter case than the 38 spl. However, at 200'/sec faster and equipped with a round nosed bullet, the 200 gn 38 spl would often penetrate completely without bringing down the individual. One NYC Police Chief was reported to have said that the 200 gn 38 was responsible for more dead cops than any other round. It was also said to lack accuracy but penetrted car badies well.
OK, there has been a bunch of discussion on the shooting capabilities of your average LEO and they aren't all that great. Combine that with a slug that penetrates without doing a lot of damage and you have LEOs at a disadvantage.
The only thing that makes the 200 gn 38 spl loading a whomper today is the use of semi-wadcutter bullets. I believe, but may be wrong, that the statistics on one shot stops with the 38 spl's 158 gn bullet increase by 20% or better when they went to the use of the semi-wadccuter bullet at the same weight. With that in mind think of what a 200 gn swc will do....
There is loading data available for the use of the 200 gn swc or rn bullet. My favorite load in 38 snubbies is the 200 gn swc over 3.8 gns of WW231 for a factory load of 770'/sec - probably around 700 from a snubby. You can handload that bullet to about 880'/sec but it is too stiff for use in lightweight snubbies, but steel frame guns handle it well, and it is an accurate load. In a friend's Diamondback that load put 6 into one hole at 25 yds. With my Airweight Bodyguard and its sister, the M37, that load groups to an inch at the same distance. This is the only load I carry in my 38 snubbies. I would say this is an excellent recipe for personal protection.
Now, if you take the same bullet and stuff it into a 357 magnum case and drop in 12.4 gns of WW296, you get 1335'/sec velocity, but a lower pressures than the 158 grainers in that caliber give you. I like that load in my 357s because it shoots so easily, doesn't recoil as bad as the 158 grainers, and is very accurate.
HTH. Mikey.