For serving in peeps and for end servings I usually use 0.18 or 0.21.
For center servings usually 0.25 or 0.26.
But this can vary greatly from all the different string materials and how many strands are used to build the string.
BCY #62 Braided serving and Diamondback braid are the ones I use both are top quality.
I use BCY #62 Braid in .020 for my center serving. I used to use .025 but found it was too tight a fit on the nocks. For peeps, end servings, etc. I use 2D.
For tying in Peeps, and tying my own nocking points I've had good results with waxed dental floss. Just a good, cheap solution. Be safe.
Shoot Straight
Derbytown
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?An archer wants to see how far away from the target he can get and still hit it. A bowhunter wants to see how close he can get to his target before he shoots.?
Dr. Mark Timney