I think you might be referring to the ".45 Remington-Thompson". It was a short-lived experimental affair that went nowhere and never was loaded in any significant quantity. Also, it did not use a 200 grain steel-core bullet, but rather the other direction, a 250 grain pointed bullet. It was a sort-of attempt at a ".45 Magnum"-type round, the case being 1/10" longer than the .45 ACP. Interesting, but not the improvement to the .45 ACP that Uncle could have made if penetration of body armor and helmets was the goal of the pistol.

There's nothing in any COW edition I have referring to any round as you cite, but the R-T load is cited in various materials pertaining to the history of the Thompson.

As an aside, tho, if you have an older Lyman 454190 mold, you can get an interesting and very deep penetrating {in soft targets, not in hard/steel} load going. That semi-pointed bullet {it is the old 1800's Army bullet configuration} will get you over 800 fps in a 1911 and at 262 grains cast of wheelweights penetrates critters very deep indeed. I believe Lyman, due to demand by the CAS has reconfigured that mold to a wider meplat {for safe feeding in lever guns} and thus destroyed the historicity of it, and also likely reduced the penetration capability somewhat.

Anyway, the first .45 Auto load WAS indeed a 200 grain bullet made for the original 1905 auto pistol, but not at higher velocities, and not loaded with a steel core.