![My Wildcat DSCN7495](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-DSCN7495.jpg)
A “wildcat” cartridge is one where a hobbyist shooter comes up with on his or her own unique cartridge usually by necking an existing one up or down to a different caliber. Some get “legitimized” when it proves so popular that a manufacturer puts it into production, such as the .257 Roberts, which is the 7x57mm Mauser necked down to .25-caliber, but most remain proprietary.
![You can see how this bullet performed on a big Montana whitetail in Realtree’s “Monster Bucks 11” video.](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-IMG_9463.jpg)
There is probably nothing you can wildcat today that hasn’t already been done, so when Hornady and Marlin teamed up to create the .450 Marlin with an all-new, never-before-seen case, I saw my opportunity to do what no one else had done and wildcat it.
![The longest shot Scott has taken with the .400 Marlin is 211 yards using the 235-grain Hawk bullet. The deer dropped in its tracks.](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-IMG_9466.jpg)
At the time,.45-caliber in-line muzzleloaders were starting to gain popularity. They’re ballistically superior to .50-caliber for deer and since they used saboted .40-caliber bullets, I reasoned that there would soon be a bunch of quality .400-inch rifle bullets on the market and made the “.400 Marlin” a true .40-caliber instead of the more commonly available .416-inch.
![This 200-grain .400-inch Hornady XTP Mag bullet took a caribou at 44 yards. What little remained of the bullet was found inside the off-shoulder.](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-IMG_9460.jpg)
The resulting .400 Marlin did what I wanted it to do—basically duplicate the old .405 Winchester like Teddy Roosevelt took his black rhino with, but in a gun with an 18 1/2-inch barrel. Unfortunately, popularity of .45-caliber in-line muzzleloaders soon fizzled and an abundance of good bullets never materialized.
![Though designed as a pistol bullet, Scott’s notes show this Hornady XTP Mag broke both shoulders of a bull caribou when fired from his .400 Marlin wildcat.](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-IMG_9461.jpg)
I’ve taken a couple of caribou using the .400 Marlin loaded with 180-grain Hornady XTP Mag pistol bullets intended for the 10mm Auto, and Hawk made up some 235- and 300-grain roundnose bullets that I also use. If you ever get a chance to watch Realtree’s “Monster Bucks 11” video, you can see the 235-grainer poleax a big Montana whitetail at 211 yards.
![Scott’s .400 Marlin wildcat duplicates the ballistics of the old .405 Winchester that Teddy Roosevelt used for rhinoceros.](https://john1911.com/wp-content/uploads/2016/07/My-Wildcat-DSCN7495.jpg)
Clearly I’ll never take a rhino with the .400 Marlin, not just because of bullets, but I can’t afford a rhino! But my .400 will always be a fun, big-bore, close-range gun for deer, bear or elk. I’d say it’s “unique,” but even though I used the then-new .450 Marlin case, it turns out that decades earlier O.A. Winters had wildcatted the .458 Win. Mag. into essentially what I had created.
Scott Mayer
www.tacticaltshirts.com
www.john1911.com
“Shooting Guns & Having Fun”
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