TripleLock,
The box does show a bit of wear, but the ammo looks pristine! Did you get it about a year ago on a GB auction? If so, I was the loser in the bidding war with you!
Do you intend to shoot any & chronograph them, or is this for display/collection only? In any case, enjoy!
I know some of the Remington and Western 200g loads were about 600 fps, but some Super Police loads were advertised at 703 (I think) and 730 fps. I've seen someone refer to a 770 fps load, but haven't ever seen original sources that claim something that high. Who knows, that may have been chrono'ed from a 8 3/8" barrel, whereas the other was from a 6" barrel (just guessing).
The box was found among some things my grandfather had about 20 years ago, so it wasn't me that was bidding against you. Unfortunately, the Spanish 38 that accompanied the box of ammo was lost in a fire about 10 years ago, but somehow the old box survived. At one time I had thought about testing a couple of rounds, but have since decided that since they've all survived together this long they deserve to continue all together.
Some time back I picked up a copy of Winchester's "Shells and Cartridges" from 1938, and Western's "Ammunition Handbook" (3rd. Edition) also from about the 1938 time frame. The Winchester handbook does not specifically list "Super Police", but their load for the 38 Special (K3868T) with a 200 grain lead bullet fired from a 6-inch barrel, reportedly gave 745 fps. at the muzzle, 247 ft. lbs. energy at the muzzle, and penetration of 7-1/2 boards of soft pine 7/8" thick at 15 ft.
The Western handbook gives a velocity for the 38 Special Super Police (Load No.K1345T), with a 200 grain Lubaloy coated bullet fired from a 6-inch barrel, of 725 fps. at 25 feet from the muzzle. It gose on to record 233 ft. lbs. energy at 25 ft., and penetration of 4 pine boards 7/8" thick at 20 ft.
I've attached PDFs of the relevant pages from both.
Jim