I'm kinda with Bob on this one..... However, slug the bore and measure the true diameter. It may be closer to .410 diameter. If so, consider a new cylinder in the wildcat, "41 Special"; which is simply a slightly shortened 41 Magnum. A new 41 magnum cylinder could work too, but the rest of the gun is old and running a full magnum load might hurt the gun and you. You would have to handload the 41 Special, but it would prevent the possibility of running the higher pressure 41 Magnum ammo through it. A simple cylinder change will preserve the originality of the gun, while making a real shooter out of it too; just don't lose the original cylinder. If the revolver is not all original, then, and only then, would I consider changing both barrel and cylinder to a better caliber. First choice, 45 Colt; second choice, 44 Special. I'm sure a 41 Special can easily equal the power of a 357 Magnum with less pressure and less muzzle blast. By the way, I once owned a first generation Colt revolver exactly like yours except in 45 Colt. Built in 1902, it was a great shooter. By all means, get yours in shootin' shape and have fun shootin' it.