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Kynoch's original standards for this cartridge were for a 400 grain bullet at 2,125 fps IN A 30" BARREL (you'll also find this data on Kynoch's website). Late run 60 Cordite Kynoch runs 2,050 fps in 24" barrels with good throats. From 1920 to 1973 Kynoch was the ONLY commercial loader of this cartridge. Of the .450/.400 3" rifles in service today, 95+% are pre-war British doubles that were regulated with the original Kynoch Cordite ammunition. It wouldn't make any sense to load factory ammunition for this cartridge that wouldn't regulate in most of the rifles chambered for it.

I was in fairly regular contact with the tech guys at Hornady during the development of this load, and again yesterday. Hornady went out of their way to match the original 60 Cordite Kynoch load exactly. Hornady's .400 pressure barrels are 24". Their 400 grain load gives 2,050 fps in 24" barrels, same as the original Kynoch. This load has NOT been limited due to concern over bore diameter variations. It duplicates the original load.

After WWII, Kynoch seems to have felt the need to compromise on the bullet diameter of the .400s, and thenceforward loaded both cartridges with .410" bullets. Shot great in both .411" and .408" guns. Hornady has done likewise. The results of their pressure testing in this regard were predictable. They tested full power loads with .410" bullets in both .410" and .408" pressure barrels. IIRC, the difference in pressure was something like 600 PSI.

Also, it is my understanding that the solid will not be their current design. It will be a copper sheathed, steel jacketed solid.
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"Serious rifles have two barrels, everything else just burns gunpowder."

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