AMO and String Length

[Chet43]

I have 3 recurve bows sitting in my closet and i am getting ready to start using them. 2 are inherited and one I bought long a go. I also have 4 strings that where given to me recently and was told that they would work on all my bows.

1st bow is 35# and 58 amo
2nd bow is 50# bear and 58" amo
3rd bow is 40# take down and 60" amo or at least that is what i think it is as it has 60 - 40 on the riser so 60" and 40#'s

I measured the strings and they are as follows:     55" exactly; 55 3/4" which I think these 2 are for both the 58" amo bows and then the 3rd string is 58 1/2"; 4th string is 57" so are these both for the 60" bow?

Why is there such a difference in the strings?

How do you determine what length string for the amo length of the bow? Does the poundage; Brand &/or model have anything to do with it? I have looked on the internet and at another forum I saw 2 different versions of determining string length and because of the difference you would not get the same result for the same bow with the 2 different methods.

Is this common and should you measure each string before you buy them no matter if custom made or off the shelf??

Reason I ask is I was told and the packages verify that the 55" & 55 3/4" strings where purchased at a store and the 57" sting may have been purchased at a store and  the 58 1/2" string may have been made by an archery shop for the 40# - 60 amo take down bow or visa versa, not positive, the gentleman could not remember regarding these 2. I would think the 57" string would be a better fit for the 60" take down than the 58 1/2" string because of what I have read on the internet that people either use a 3" or 4" reduction from amo when making or buying strings???

Sorry for the rambling but this is confusing and bothersome to me and I would like to learn the proper methods for determining string length for any recurve or long bow? Thanks for taking the time to read and reply to this message.

[quadrafire]

Chet I'm no expert, but I think a recurve string is approx 4 in shorter than bow length measured nock-nock across the face of the bow. That string length can be adjusted by twisting/untwisting the string to get the appropriate brace height.

[Tracker0721]

Poundage has no matter in bow strings. Most strings like I make can hold over 600# of pressure. Just gotta get that out there.

Now for strings, twisting them tighter will shorten, looser will lengthen, but they should be close to 4" less then AMO. The reason is amo is taking a tape and pulling it from nock groove to nock groove. So a 58" AMO bow would require a 54" long string in order to get the (roughly) correct brace height. Too short and your bow will be holding back too much pressure in the limbs, as if already partly drawn. Too loose and you'll not only smack the jeepers out of your arm but the bow will also get to whip too close to unbraced position and damage the limbs(they'll fling to far Foward).

So with your strings, if they are flemish strings, twist em up. If I don't hook my loops together they always lose an inch or so. About 2 twists should be a quarter inch.