I use Hornady's TC die too & it does a fine job.
Yes, deep seating gives you more bullet-case tension & with plated bullets that's welcome.
If you don't deep seat to roughly my OAL", above, the taper crimp won't be forward of the ogive to give you the benefit you want.
2400 is a slow powder that's good for downloading. Slower powders, with plated bullets, don't burn well because you can't get enough of a crimp. Moderate speed powders like Power Pistol, Unique, LongShot or BlueDot do better in reduced loads with plated bullets, IMO. I save my 2400 powder for my 41 & 44 Mag loads.
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