The basic comments from the builders and shooters of these guns is, the std length linebaughs are at the limits of what one can handle in a sizgun, the longs are just too much. Very few folks can handle the std max loads of 440 gr @ 1350 fps, the max's do 1500.
Personally, I find the 480 at my reasonable limit. I've fired several std 475 and 500 linebaughs, and they are extremely difficult to control at full power levels. I've also realized that anything that I wouldn't hunt with a 480, I wouldn't hunt with a handgun.
When Linebaugh was first making the 475 and the 500 he made a 1.4 and 1.6 in both caliber. I can not remember why he picked the 1.4 over the 1.6. I did not know he sold any of the gun with the 1.6 case. you might go to www.linebaughcustomsixguns.com this is his wedsite and ask him. He also made a 458 Linebaugh
Paul
He builds guns on both 1.4" and 1.6" in .475 and .500 calibers...the 1.6" gun is built on the Ruger Maximum frame and is twice the money & recoil for a couple inches more penetration. The 1.6" can physically hurt you (so can the 1.4") and is more of a "coffee table" gun...something for bragging rights/collectors to have. I have a .500 1.4" for daily carry among Alaska's bears and I don't even load it to max loads for controllability. Any of John's guns loaded hot can make the gun climb over your head in recoil...that's bad news when Mr. Brownie is coming over to visit. 435 gr. cast bullets at about 1200 fps is a "big stick" and easy on the gun & shooter.