Less Is More When It Comes To Bigbore Sixguns
The .475 Cooper is a reduced version of the .475 Linebaugh.
When the .357 Magnum hit the sixgunning world in 1935, it was billed as “more powerful than any .44 or .45!” Twenty years later it took a very far backseat to the new champion, the .44 Magnum. Now we had surely arrived. It would be impossible to go any further.
Then came the .454 Casull and the .475 and .500 Linebaughs, all excellent cartridges for their intended use. Even this was not the end as we soon had Maximum length versions of the same basic cartridges. By the time we hit the latter, more and more sixgunners began to think that enough was enough.
One of these pistoleros who appreciated bigbores, but did not fancy big recoil was one of our readers, Don Wilson. He contacted me about a couple of sixguns he had built up with the inquiry as to whether or not I would be interested in trying them out. Me interested in a bigbore single-action sixgun? Does God make little green apples?
A 380 gr. slug at 725 fps is a lot more pleasant to shoot than a fullbore Linebaugh.
Bigbore Appreciation
Proper arrangements adhering to all Federal laws were made to have Wilson’s two pet sixguns shipped to me for testing.
Wilson wanted a really bigbore sixgun with six-shot capacity on a standard Ruger Blackhawk revolver using a rechambered Blackhawk cylinder. The desired result would be a .475 caliber using a 380 gr. bullet at a modest 800 to 900 fps.
Wilson did his homework. First he carefully measured the cylinder and figured he could get by with a rim diameter of .545″ and an overall length of 1.636″ and still allow some room in the end of the cylinder mouth just in case a bullet should happen to move forward under recoil.
Both Wilson and his gunsmith, Larry Cooper, consulted with John Linebaugh, then had Cliff LaBounty rebore and Dave Adams rechamber a .45-70 Contender to .475 Cooper. Then the testing began. Wilson settled on a load of 20.0 grs. of H4227 under a 380 gr. bullet in the Contender barrel.
The First .475 Cooper Six-Shot Bigbore
With gratifying results, Cooper rechambered a Blackhawk to .475 Cooper, rebarreled and slicked up everything, and the first .475 Cooper six-shot bigbore was born.
Wilson found 17.0 grs. of H4227 was a very pleasant shooting load. I went with 17.5 grs., because that was where my first setting of the powder measure happened to fall. These clocked at 725 fps, a most pleasant shooting 725 fps, and certainly would anchor any whitetail or mule deer that ever walked.
A more simple conversion is done to simply provide a rimmed case for revolvers chambered for the .50 Action Express. Brass is made from the .348 Winchester cut to the same length as the .50 AE, cylinders are slightly recessed to accept the rims of the new cartridge, and the capability of still accepting .50 AE brass is maintained. With this .50 Rimmed and the same powder charge using the same weight bullet, muzzle velocity is 775 fps and still very pleasant to shoot.
It just goes to prove that in bigbore sixguns, more really is less.
Get more revolver stories every week!
By submitting this form, you are consenting to receive marketing emails from: . You can revoke your consent to receive emails at any time by using the SafeUnsubscribe® link, found at the bottom of every email. Emails are serviced by Constant Contact
