If the barrel is 24" long and your ramrod turns more than a third of a revolution, you probably have a 1:48 twist. As far as I know, they came in 2 twists, 1:48 and 1:twentysomething. It's hard to judge exactly.

If you get the ramrod in the barrel some short distance, then measure up the ramrod say 12 inches and wrap some tape at that point, you may get a more accurate reading on the amount of twist you can observe as you push the ramrod in for that measured 12 inches. Then multiply by 4 to get the twist for 48 inches. My guess is you will come out to a number close to 1. If you do, its 1:48. If your number is close to 2, then its a 1:21, or 24, or 28 or whatever other rate they used.