Though superficially similar to the old 401 powermag, this would be a much higher-pressure, and therefore higher-power round in either magnum- or casull-caselength.
The 401 bobcat in both 1.29” and 1.40” versions would be a better comparison, however it uses the 220 swift as a parent cartridge, which unfortunately is tapered. Using 30-30 brass like the 400 GNR gives the advantage of a straight wall. Even better, 225 Win brass gives the superior .473 rim diameter and 0.049” rim thickness.
Whether 401 GNR “gets there lots easier” depends on knowing where “there” is.
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400 GNR - Short?
- Keith, 2026-05-11, 18:42
![[*]](themes/default/images/complete_thread.png "Open whole thread")
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Yes, it’s called the .401 Herters Supermag
- WB, 2026-05-11, 20:55
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No, not quite
- Keith, 2026-05-12, 18:37
- I think the .400" is too big for a .30-30, .225, whatever - WB, 2026-05-13, 13:10
- 401 GNR #2- 445 SM necked down (nm) - Sean Harper, 2026-05-12, 04:34
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No, not quite
- Keith, 2026-05-12, 18:37
- neck ream - AlanT, 2026-05-11, 19:19
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Yes, it’s called the .401 Herters Supermag
- WB, 2026-05-11, 20:55