Depends on how long your arms are, how long your neck is and the contour of your sholders, and how fat your face it...No rule of thumb...

But the main thing is when you throw the gun to your shoulder with your eyes shut and open them that your looking right at your sights...

14.75 tells me your close to 7 ft. tall...I am 6-2 and long and almost lean and I shoot a 14" pull on a double rifle...Mainly you want to slightly crawl the stock and when you shoot the stock needs to be long enough to keep your thumb out of your nose..any longer and the butt will hang on your clothing when you bring the gun up...

Best way to figure out what you need is try some guns and when you find one that just feels like it belongs to you, then take those measurements...or use a try gun to get your specs....

The human body can about adjust to any gun if the shooter uses it enough, especially a shotgun...