It would make no sense to shorten the already-short neck of the .35 Remington - I doubt it would even hold a bullet if shortened by 5/16". .444 brass that is 0.313" shorter? Why? Hornady is a member of SAAMI and would have to adhere to the dimensional standards that other members do. I cannot believe the brass is materially shorter than the SAAMI standard.
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It is though, at least with the 450 & 45-70, I have them sitting side by side at my computer, I hear the 444 is the same way, I have not compared the 35REM. The pointed bullets obviously have to be considerably longer than a flat nose of the same weight, when you factor in the syn. tip which weighs very little, the bullet gets even longer. So, with the 325gr as in the 45-70, this is a long bullet. The overall length is a critical factor, otherwise the round will not cycle into the chamber. So, they had to shorten the case, still long enough for a stiff charge of the powder they use, ( may be special powder) but short enough to cycle.
And for that reason, I don't see them offering bullets only. If you use the std case, the loaded round would be too long. They cannot offer a second crimping groove, the groove is just off the ogive now! Look's like they are in abox for offering these components.